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1.  Alström Syndrome protein ALMS1 localizes to basal bodies of cochlear hair cells and regulates cilium-dependent planar cell polarity 
Human Molecular Genetics  2010;20(3):466-481.
Alström Syndrome is a life-threatening disease characterized primarily by numerous metabolic abnormalities, retinal degeneration, cardiomyopathy, kidney and liver disease, and sensorineural hearing loss. The cellular localization of the affected protein, ALMS1, has suggested roles in ciliary function and/or ciliogenesis. We have investigated the role of ALMS1 in the cochlea and the pathogenesis of hearing loss in Alström Syndrome. In neonatal rat organ of Corti, ALMS1 was localized to the basal bodies of hair cells and supporting cells. ALMS1 was also evident at the basal bodies of differentiating fibrocytes and marginal cells in the lateral wall. Centriolar ALMS1 expression was retained into maturity. In Alms1-disrupted mice, which recapitulate the neurosensory deficits of human Alström Syndrome, cochleae displayed several cyto-architectural defects including abnormalities in the shape and orientation of hair cell stereociliary bundles. Developing hair cells were ciliated, suggesting that ciliogenesis was largely normal. In adult mice, in addition to bundle abnormalities, there was an accelerated loss of outer hair cells and the progressive appearance of large lesions in stria vascularis. Although the mice progressively lost distortion product otoacoustic emissions, suggesting defects in outer hair cell amplification, their endocochlear potentials were normal, indicating the strial atrophy did not affect its function. These results identify previously unrecognized cochlear histopathologies associated with this ciliopathy that (i) implicate ALMS1 in planar cell polarity signaling and (ii) suggest that the loss of outer hair cells causes the majority of the hearing loss in Alström Syndrome.
doi:10.1093/hmg/ddq493
PMCID: PMC3016908  PMID: 21071598
2.  Novel Alu Retrotransposon Insertion Leading to Alström Syndrome 
Human Genetics  2011;131(3):407-413.
Alström Syndrome is a clinically complex disorder characterized by childhood retinal degeneration leading to blindness, sensorineural hearing loss, obesity, type 2 diabetes mellitus, cardiomyopathy, systemic fibrosis, and pulmonary, hepatic, and renal failure. Alström Syndrome is caused by recessively inherited mutations in the ALMS1 gene, which codes for a putative ciliary protein. Alström Syndrome is characterized by extensive allelic heterogeneity, however founder effects have been observed in some populations. To date, more than 100 causative ALMS1 mutations have been identified, mostly frameshift and nonsense alterations resulting in termination signals in ALMS1. Here we report a complex Turkish kindred in which sequence analysis uncovered an insertion of a novel 333 basepair Alu Ya5 SINE retrotransposon in the ALMS1 coding sequence, a previously unrecognized mechanism underlying mutations causing Alström Syndrome. It is extraordinarily rare to encounter the insertion of an Alu retrotransposon in the coding sequence of a gene. The high frequency of the mutant ALMS1 allele in this isolated population suggests that this recent retrotransposition event spread quickly, and may be used as a model to study the population dynamics of deleterious alleles in isolated communities.
doi:10.1007/s00439-011-1083-9
PMCID: PMC3264847  PMID: 21877133
Alström Syndrome; ALMS1; Alu Ya5; Insertion Mutation; Short Interspersed Nuclear Elements (SINE)
3.  A Role for Alström Syndrome Protein, Alms1, in Kidney Ciliogenesis and Cellular Quiescence  
PLoS Genetics  2007;3(1):e8.
Premature truncation alleles in the ALMS1 gene are a frequent cause of human Alström syndrome. Alström syndrome is a rare disorder characterized by early obesity and sensory impairment, symptoms shared with other genetic diseases affecting proteins of the primary cilium. ALMS1 localizes to centrosomes and ciliary basal bodies, but truncation mutations in Alms1/ALMS1 do not preclude formation of cilia. Here, we show that in vitro knockdown of Alms1 in mice causes stunted cilia on kidney epithelial cells and prevents these cells from increasing calcium influx in response to mechanical stimuli. The stunted-cilium phenotype can be rescued with a 5′ fragment of the Alms1 cDNA, which resembles disease-associated alleles. In a mouse model of Alström syndrome, Alms1 protein can be stably expressed from the mutant allele and is required for cilia formation in primary cells. Aged mice developed specific loss of cilia from the kidney proximal tubules, which is associated with foci of apoptosis or proliferation. As renal failure is a common cause of mortality in Alström syndrome patients, we conclude that this disease should be considered as a further example of the class of renal ciliopathies: wild-type or mutant alleles of the Alström syndrome gene can support normal kidney ciliogenesis in vitro and in vivo, but mutant alleles are associated with age-dependent loss of kidney primary cilia.
Author Summary
Alström syndrome is a rare genetic disorder caused by mutations in the ALMS1 gene. The disease is characterized by blindness, deafness, and metabolic disorders. These symptoms are reminiscent of diseases affecting the primary cilium, a cellular appendage with a role in sensing changes to the extracellular environment. In addition, kidney failure is a frequent cause of death in Alström syndrome patients, and recent studies have suggested a causal relationship between defects in primary cilia and cystic kidney diseases. In this paper, we show that ALMS1 protein is required to form cilia in kidney cells. Mutant alleles of the gene that are similar to those seen in the human disease are able to support cilia formation in cell culture and in animals. However, a defect in the function of the disease alleles is uncovered in older mice: cilia are lost from the kidney cells, and this is associated with an increase in cellular proliferation and cell death. The data are consistent with a requirement for ALMS1 in ciliogenesis and suggest inclusion of Alström syndrome among the growing class of cilia-related pathologies.
doi:10.1371/journal.pgen.0030008
PMCID: PMC1761047  PMID: 17206865
4.  A Role for Alström Syndrome Protein, Alms1, in Kidney Ciliogenesis and Cellular Quiescence  
PLoS Genetics  2007;3(1):e8.
Premature truncation alleles in the ALMS1 gene are a frequent cause of human Alström syndrome. Alström syndrome is a rare disorder characterized by early obesity and sensory impairment, symptoms shared with other genetic diseases affecting proteins of the primary cilium. ALMS1 localizes to centrosomes and ciliary basal bodies, but truncation mutations in Alms1/ALMS1 do not preclude formation of cilia. Here, we show that in vitro knockdown of Alms1 in mice causes stunted cilia on kidney epithelial cells and prevents these cells from increasing calcium influx in response to mechanical stimuli. The stunted-cilium phenotype can be rescued with a 5′ fragment of the Alms1 cDNA, which resembles disease-associated alleles. In a mouse model of Alström syndrome, Alms1 protein can be stably expressed from the mutant allele and is required for cilia formation in primary cells. Aged mice developed specific loss of cilia from the kidney proximal tubules, which is associated with foci of apoptosis or proliferation. As renal failure is a common cause of mortality in Alström syndrome patients, we conclude that this disease should be considered as a further example of the class of renal ciliopathies: wild-type or mutant alleles of the Alström syndrome gene can support normal kidney ciliogenesis in vitro and in vivo, but mutant alleles are associated with age-dependent loss of kidney primary cilia.
Author Summary
Alström syndrome is a rare genetic disorder caused by mutations in the ALMS1 gene. The disease is characterized by blindness, deafness, and metabolic disorders. These symptoms are reminiscent of diseases affecting the primary cilium, a cellular appendage with a role in sensing changes to the extracellular environment. In addition, kidney failure is a frequent cause of death in Alström syndrome patients, and recent studies have suggested a causal relationship between defects in primary cilia and cystic kidney diseases. In this paper, we show that ALMS1 protein is required to form cilia in kidney cells. Mutant alleles of the gene that are similar to those seen in the human disease are able to support cilia formation in cell culture and in animals. However, a defect in the function of the disease alleles is uncovered in older mice: cilia are lost from the kidney cells, and this is associated with an increase in cellular proliferation and cell death. The data are consistent with a requirement for ALMS1 in ciliogenesis and suggest inclusion of Alström syndrome among the growing class of cilia-related pathologies.
doi:10.1371/journal.pgen.0030008
PMCID: PMC1761047  PMID: 17206865
5.  The Alström Syndrome Protein, ALMS1, Interacts with α-Actinin and Components of the Endosome Recycling Pathway 
PLoS ONE  2012;7(5):e37925.
Alström syndrome (ALMS) is a progressive multi-systemic disorder characterized by cone-rod dystrophy, sensorineural hearing loss, childhood obesity, insulin resistance and cardiac, renal, and hepatic dysfunction. The gene responsible for Alström syndrome, ALMS1, is ubiquitously expressed and has multiple splice variants. The protein encoded by this gene has been implicated in ciliary function, cell cycle control, and intracellular transport. To gain better insight into the pathways through which ALMS1 functions, we carried out a yeast two hybrid (Y2H) screen in several mouse tissue libraries to identify ALMS1 interacting partners. The majority of proteins found to interact with the murine carboxy-terminal end (19/32) of ALMS1 were α-actinin isoforms. Interestingly, several of the identified ALMS1 interacting partners (α-actinin 1, α-actinin 4, myosin Vb, rad50 interacting 1 and huntingtin associated protein1A) have been previously associated with endosome recycling and/or centrosome function. We examined dermal fibroblasts from human subjects bearing a disruption in ALMS1 for defects in the endocytic pathway. Fibroblasts from these patients had a lower uptake of transferrin and reduced clearance of transferrin compared to controls. Antibodies directed against ALMS1 N- and C-terminal epitopes label centrosomes and endosomal structures at the cleavage furrow of dividing MDCK cells, respectively, suggesting isoform-specific cellular functions. Our results suggest a role for ALMS1 variants in the recycling endosome pathway and give us new insights into the pathogenesis of a subset of clinical phenotypes associated with ALMS.
doi:10.1371/journal.pone.0037925
PMCID: PMC3365098  PMID: 22693585
6.  Alms1-disrupted mice recapitulate human Alström syndrome 
Human molecular genetics  2005;14(16):2323-2333.
Mutations in the human ALMS1 gene cause Alström syndrome (AS), a progressive disease characterized by neurosensory deficits and by metabolic defects including childhood obesity, hyperinsulinemia and Type 2 diabetes. Other features that are more variable in expressivity include dilated cardiomyopathy, hypertrigly-ceridemia, hypercholesterolemia, scoliosis, developmental delay and pulmonary and urological dysfunctions. ALMS1 encodes a ubiquitously expressed protein of unknown function. To obtain an animal model in which the etiology of the observed pathologies could be further studied, we generated a mouse model using an Alms1 gene-trapped ES cell line. Alms1−/− mice develop features similar to patients with AS, including obesity, hypogonadism, hyperinsulinemia, retinal dysfunction and late-onset hearing loss. Insulin resistance and increased body weight are apparent between 8 and 12 weeks of age, with hyperglycemia manifesting at ~16 weeks of age. In addition, Alms1−/− mice have normal hearing until 8 months of age, after which they display abnormal auditory brainstem responses. Diminished cone ERG b-wave response is observed early, followed by the degeneration of photoreceptor cells. Electron microscopy revealed accumulation of intracellular vesicles in the inner segments of photoreceptors, whereas immunohistochemical analysis showed mislocalization of rhodopsin to the outer nuclear layer. These findings suggest that ALMS1 has a role in intracellular trafficking.
doi:10.1093/hmg/ddi235
PMCID: PMC2862911  PMID: 16000322
7.  Transcriptional regulation of the Alström syndrome gene ALMS1 by members of the RFX family and Sp1 
Gene  2010;460(1-2):20-29.
Mutations in the human gene ALMS1 cause Alström syndrome, a disorder characterised by neurosensory degeneration, metabolic defects and cardiomyopathy. ALMS1 encodes a centrosomal protein implicated in the assembly and maintenance of primary cilia. Expression of ALMS1 varies between tissues and recent data suggest that its transcription is modulated during adipogenesis and growth arrest. However the ALMS1 promoter has not been defined. This study focused on identifying and characterising the ALMS1 proximal promoter, initially by using 5' RACE to map transcription start sites. Luciferase reporter assay and EMSA data strongly suggest that ALMS1 transcription is regulated by the ubiquitous factor Sp1. In addition, reporter assay, EMSA, chromatin immunoprecipitation and RNA interference data indicate that ALMS1 transcription is regulated by regulatory factor X (RFX) proteins. These transcription factors are cell-type restricted in their expression profile and known to regulate genes of the ciliogenic pathway. We show binding of RFX proteins to an evolutionarily conserved X-box in the ALMS1 proximal promoter and present evidence that these proteins are responsible for ALMS1 transcription during growth arrest induced by low serum conditions. In summary, this work provides the first data on transcription factors regulating general and context-specific transcription of the disease-associated gene ALMS1.
doi:10.1016/j.gene.2010.03.015
PMCID: PMC2913254  PMID: 20381594
CAGE, cap-analysis of gene expression; cDNA, DNA complementary to RNA; ChIP, chromatin immunoprecipitation; EMSA, electrophoretic mobility shift assay; FCS, fetal calf serum; LMC, low-mobility complex; NE, nuclear extract; PCR, polymerase chain reaction; RACE, rapid amplification of cDNA ends; RFX, regulatory factor X; RNAi, RNA interference; RT-PCR, reverse transcription-PCR; s.d., standard deviation; SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; s.e.m., standard error of the mean; siRNA, small interfering RNA; TBP, TATA-binding protein; TSS, transcription start site; transcription; promoter; X-box; GC-box; cilia
8.  Extreme clinical variability of dilated cardiomyopathy in two siblings with Alström syndrome 
Pediatric cardiology  2012;34(2):455-458.
Alström syndrome (ALMS) is a rare autosomal recessive disorder caused by mutations in the ALMS1 gene. We report on two brothers, 2 and 3 years of age, diagnosed with Alström syndrome who initially presented in infancy with severe dilated cardiomyopathy during febrile respiratory infection. The disease course in the two siblings was marked by significant intra-familial variability. While cardiomyopathy in the older sibling has mainly resolved allowing for the discontinuation of medical therapy, heart function in the younger sibling continues to deteriorate despite maximal drug support with furosemide, carvedilol, captopril and aldospirone. Genetic analysis revealed homozygous mutations, c.8008C>T (R2670X), in ALMS1 resulting in premature protein truncation. This report further emphasizes the exceptional intra-familial variability of ALMS, mainly in the natural course of cardiac disease.
doi:10.1007/s00246-012-0296-6
PMCID: PMC3779600  PMID: 22447358
Alström syndrome; dilated cardiomyopathy; autosomal recessive; ALMS1 gene
9.  Coronary artery disease in Alström syndrome 
Alström syndrome (ALMS) is a rare autosomal recessive condition, caused by mutations in the ALMS1 gene located on the short arm of chromosome 2. This gene codes for a protein linked with the centrosome, whose precise function is unknown. This condition was first described by Alström in 1959. ALMS is a multisystem condition that is characterised by childhood onset of blindness secondary to rod-cone retinal degeneration and dilated cardiomyopathy with heart failure, which often presents in infanthood and may recur later in life. Metabolic abnormalities including hypertriglyceridemia, liver steatosis, insulin resistance and type 2 diabetes mellitus are common, often occurring in association with obesity. Other abnormalities include endocrinological disturbances, such as thyroid disorder, growth hormone deficiency, hypogonadism and, in women, hyperandrogenism. This syndrome is also associated with sensorineural hearing loss, renal failure secondary to glomerulo-fibrosis, and fibrotic lung disease. Multiorgan fibrotic infiltration is the common feature in all cases. Considering the history of diabetes, hypertension, dyslipidemia, obesity and renal dysfunction in ALMS, it would be expected that this group of patients could develop coronary artery disease (CAD). But such cases have not been reported so far. We report a case of premature onset of CAD in one of the longest surviving patient with ALMS.
doi:10.1038/ejhg.2011.168
PMCID: PMC3234522  PMID: 21897446
Alström syndrome; complications; coronary artery disease
10.  Alström Syndrome: Genetics and Clinical Overview 
Current Genomics  2011;12(3):225-235.
Alström syndrome is a rare autosomal recessive genetic disorder characterized by cone-rod dystrophy, hearing loss, childhood truncal obesity, insulin resistance and hyperinsulinemia, type 2 diabetes, hypertriglyceridemia, short stature in adulthood, cardiomyopathy, and progressive pulmonary, hepatic, and renal dysfunction. Symptoms first appear in infancy and progressive development of multi-organ pathology leads to a reduced life expectancy. Variability in age of onset and severity of clinical symptoms, even within families, is likely due to genetic background.
Alström syndrome is caused by mutations in ALMS1, a large gene comprised of 23 exons and coding for a protein of 4,169 amino acids. In general, ALMS1 gene defects include insertions, deletions, and nonsense mutations leading to protein truncations and found primarily in exons 8, 10 and 16. Multiple alternate splice forms exist. ALMS1 protein is found in centrosomes, basal bodies, and cytosol of all tissues affected by the disease. The identification of ALMS1 as a ciliary protein explains the range of observed phenotypes and their similarity to those of other ciliopathies such as Bardet-Biedl syndrome.
Studies involving murine and cellular models of Alström syndrome have provided insight into the pathogenic mechanisms underlying obesity and type 2 diabetes, and other clinical problems. Ultimately, research into the pathogenesis of Alström syndrome should lead to better management and treatments for individuals, and have potentially important ramifications for other rare ciliopathies, as well as more common causes of obesity and diabetes, and other conditions common in the general population.
doi:10.2174/138920211795677912
PMCID: PMC3137007  PMID: 22043170
ALMS1; Alström syndrome; ciliopathy; truncal obesity.
11.  Centriolar Association of ALMS1 and Likely Centrosomal Functions of the ALMS Motif–containing Proteins C10orf90 and KIAA1731 
Molecular Biology of the Cell  2010;21(21):3617-3629.
This study reveals the subcentrosomal distribution of ALMS1, a human protein implicated in primary cilium formation and maintenance, and provides new insight into its centrosome-related functions. The first functional data on two human proteins sharing C-terminal sequence similarity with ALMS1 are also presented.
Mutations in the human gene ALMS1 cause Alström syndrome, a rare progressive condition characterized by neurosensory degeneration and metabolic defects. ALMS1 protein localizes to the centrosome and has been implicated in the assembly and/or maintenance of primary cilia; however its precise function, distribution within the centrosome, and mechanism of centrosomal recruitment are unknown. The C-terminus of ALMS1 contains a region with similarity to the uncharacterized human protein C10orf90, termed the ALMS motif. Here, we show that a third human protein, the candidate centrosomal protein KIAA1731, contains an ALMS motif and that exogenously expressed KIAA1731 and C10orf90 localize to the centrosome. However, based on deletion analysis of ALMS1, the ALMS motif appears unlikely to be critical for centrosomal targeting. RNAi analyses suggest that C10orf90 and KIAA1731 have roles in primary cilium assembly and centriole formation/stability, respectively. We also show that ALMS1 localizes specifically to the proximal ends of centrioles and basal bodies, where it colocalizes with the centrosome cohesion protein C-Nap1. RNAi analysis reveals markedly diminished centrosomal levels of C-Nap1 and compromised cohesion of parental centrioles in ALMS1-depleted cells. In summary, these data suggest centrosomal functions for C10orf90 and KIAA1731 and new centriole-related functions for ALMS1.
doi:10.1091/mbc.E10-03-0246
PMCID: PMC2965680  PMID: 20844083
12.  Arrayed primer extension technology simplifies mutation detection in Bardet–Biedl and Alström syndrome 
Bardet–Biedl syndrome (BBS; OMIM no. 209 900) and Alström syndrome (ALMS; OMIM no. 203 800) are rare, multisystem genetic disorders showing both a highly variable phenotype and considerable phenotypic overlap; they are included in the emerging group of diseases called ciliopathies. The genetic heterogeneity of BBS with 14 causal genes described to date, serves to further complicate mutational analysis. The development of the BBS–ALMS array which detects known mutations in these genes has allowed us to detect at least one mutation in 40.5% of BBS families and in 26.7% of ALMS families validating this as an efficient and cost-effective first pass screening modality. Furthermore, using this method, we found two BBS families segregating three BBS alleles further supporting oligogenicity or modifier roles for additional mutations. We did not observe more than two mutations in any ALMS family.
doi:10.1038/ejhg.2010.207
PMCID: PMC3060323  PMID: 21157496
Bardet–Biedl syndrome; BBS; Alström syndrome; ALMS1; arrayed primer extension; mutation analysis
13.  Differences in the clinical spectrum of two adolescent male patients with Alström syndrome 
Clinical dysmorphology  2013;22(1):7-12.
Alström syndrome is a rare disorder typified by early childhood obesity, neurosensory deficits, cardiomyopathy, progressive renal and hepatic dysfunction, and endocrinological features such as severe insulin resistance, type 2 diabetes, hyperlipidemia, and hypogonadism. Widespread fibrosis leads to multiple organ failure. Mutations in ALMS1 cause Alström’s syndrome. Two age-matched, unrelated adolescent males of Serbian descent with Alström syndrome underwent an extensive workup of blood chemistries, and ophthalmological, audiological, and genetic evaluations. Although both showed typical features of Alström syndrome in childhood, several differences were observed that have not been reported previously. Patient 1 was first studied at the age of 13 years for multisystemic disease and re-evaluated at the age of 15.5 years. Patient 2 is a 15-year-old boy who presented at birth with epilepsy and psychomotor developmental delay and generalized tonic–clonic seizures with severe cognitive impairment, features not documented previously in this syndrome. Sequencing analysis indicated two novel ALMS1 mutations in exon 8: p.E1055GfsX4 and p.T1386NfsX15. Metabolic and physiological similarities were observed in both patients, including severe insulin resistance, and truncal obesity with fat loss suggestive of partial lipodystrophy, supporting evidence for a role for ALMS1 in adipose tissue function. The unusual phenotypes of clonic–tonic seizures and severe cognitive abnormalities and lipodystrophy-like adiposity pattern have not been documented previously in Alström syndrome and may be an under-reported abnormality.
doi:10.1097/MCD.0b013e32835b9017
PMCID: PMC3619948  PMID: 23188138
ALMS1; Alström syndrome; hypogonadotropic hypogonadism; partial lipodystrophy; tonic–clonic epilepsy
14.  Caloric restriction in Alström syndrome prevents hyperinsulinemia 
Alström syndrome (AS; MIM 203800) is an autosomal recessive disorder characterized by cone-rod dystrophy, dilated cardiomyopathy, sensorineural hearing impairment, developmental delay, and most case had both childhood-onset obesity and hyperinsulinemia. Currently, the pathogenesis of this disease is not clear. Here we report an 18-month-old boy with Alström syndrome. He had obesity but with normal insulin and glucose levels. Molecular analysis of the ALMS1 gene revealed a homozygous deletion 11116_11134 del n(19) in exon 16. His body mass index decreased from 25.0 to 20.7 after calorie restriction for 9 months, and his insulin and glucose levels remained normal. Finding in this case suggests that hyperinsulinemia is a secondary event in Alström syndrome, and early-commenced treatment prevents hyperinsulinemia.
doi:10.1002/ajmg.a.32730
PMCID: PMC2820246  PMID: 19283853
Alström syndrome; ALMS1; obesity; hyperinsulinemia; calorie restriction
15.  High copy arrays containing a sequence upstream of mec-3 alter cell migration and axonal morphology in C. elegans 
Background
The Caenorhabditis elegans gene mec-3 encodes a LIM-homeodomain protein that is a master regulator of touch receptor neuron genes. Two of the touch neurons, the ALM neurons, are generated in the anterior of the animal and then migrate to near the middle of the animal. In animals transformed with a sequence upstream of mec-3, the ALM touch receptor neurons failed to migrate to their normal positions and sometimes migrated in the wrong direction, and the PLM touch receptor neurons showed axonal defects. Here we characterize this effect and identify the sequence causing the cell migration and axonal defects.
Results
The ALM migration defect did not result from RNA interference (RNAi), nonspecific effects of carrying a transgenic array, expression of GFP, or the marker gene used to make the transformants. Instead, the ALM migration defect resulted from transgenic arrays containing many copies of a specific 104 bp DNA sequence. Transgenic arrays containing this sequence did not affect all cell migrations.
Conclusions
The mec-3 upstream sequence appeared to be sequestering (titrating out) a specific DNA-binding factor that is required for the ALMs to migrate correctly. Because titration of this factor could reverse the direction of ALM migrations, it may be part of a program that specifies both the direction and extent of ALM migrations. mec-3 is a master regulator of touch receptor neuron genes, so the factor or factors that bind this sequence may also be involved in specifying the fate of touch receptor neurons.
doi:10.1186/1471-213X-1-2
PMCID: PMC31336  PMID: 11182881
16.  Molecular approach in the study of Alström syndrome: Analysis of ten Spanish families 
Molecular Vision  2012;18:1794-1802.
Purpose
To describe the clinical and genetic findings in 11 Spanish patients with confirmed (n=5) or suspected (n=6) Alström syndrome (AS).
Methods
Patients underwent clinical evaluation, and were screened for variations in Alström syndrome 1 gene (ALMS1) using a genotyping microarray from Asper Ophthalmics and by direct sequencing of coding exons 8, 10, and 16 of ALMS1. Furthermore, we analyzed the presence of the A229T variant of retinitis pigmentosa GTPase regulator-interacting protein 1-like gene (RPGRIP1L) with direct sequencing of coding exon 6.
Results
A great phenotypic variability was observed in our patients. Four mutations in ALMS1—two novel nonsense mutations in one family (p.Y1715X and p.S616X), one previously described mutation in homozygous state in another family (p.V3597Efs*4), and a likely pathogenic missense variation p.P1822L in a third family—were identified with direct sequencing. All patients were homozygous for 229A allele of RPGRIP1L, with the exception of a p.A229T heterozygous patient.
Conclusions
Our findings expand the spectrum of ALMS1 mutations causing Alström syndrome. The phenotypic differences between patients could be attributed to interactions with other genes inherited independently from the ALMS1 gene or with environmental factors. A clear understanding of the phenotypic spectrum in AS will be important to unravel the molecular mechanisms underlying this syndrome.
PMCID: PMC3413414  PMID: 22876109
17.  Management of cervical myelopathy due to ossification of posterior longitudinal ligament in a patient with Alström syndrome 
European Spine Journal  2012;21(12):2418-2424.
Introduction
Alström syndrome (AS) is a rare autosomal recessive genetic disorder with multisystemic involvement characterised by early blindness, hearing loss, obesity, insulin resistance, diabetes mellitus, dilated cardiomyopathy, and progressive hepatic and renal dysfunction. The clinical features, time of onset and severity can vary greatly among different patients. Many of the phenotypes are often not present in infancy but develop throughout childhood and adolescence. Recessively inherited mutations in ALMS1 gene are considered to be responsible for the causation of AS. Musculoskeletal manifestations including scoliosis and kyphosis have been previously described.
Case report
Here, we present a patient with AS who presented with cervical myelopathy due to extensive flowing ossification of the anterior and posterior longitudinal ligaments of the cervical spine resulting in cervical spinal cord compression. The presence of an auto-fused spine in an acceptable sagittal alignment, in the background of a constellation of medical comorbidities, which necessitated a less morbid surgical approach, favored a posterior cervical laminectomy decompression in this patient. Postoperatively, the patient showed significant neurological recovery with improved function. Follow-up MRI showed substantial enlargement of the spinal canal with improved space available for the spinal cord. The rarity of the syndrome, cervical myelopathy due to ossified posterior longitudinal ligament as a disease phenotype and the treatment considerations for performing a posterior cervical decompression have been discussed in this Grand Rounds’ case presentation.
doi:10.1007/s00586-012-2305-0
PMCID: PMC3508221  PMID: 22576155
Alström syndrome; Cervical; Myelopathy; Laminectomy
18.  High resolution spectral domain optical coherence tomography (OCT) images of Alström Syndrome 
Alström syndrome (ALMS1) is a multisystemic disorder characterized by cone–rod dystrophy, hearing loss, obesity, insulin resistance and hyperinsulinemia, type 2 diabetes mellitus, dilated cardiomyopathy, and progressive hepatic and renal dysfunction.The cone-rod retinal dystrophy usually develops within a few weeks after birth. We examined a young boy with Alstrom by means of microperimetry MP-1 and optical coherence tomography (OCT) Spectral Domain.
Instead of the typical alterations observed in cone-rod dystrophies, the characteristics of the central foveal tissue suggest signs of retinal immaturity, with only a single layer of short thick cones and rods as well as immature short outer segments. High- speed/ high- resolution spectral domain OCT allowed for the first time a detailed analysis of retinal layers in a young patient with Alstrom Syndrome.
doi:10.3928/01913913-20100507-05
PMCID: PMC3015152  PMID: 21158358
alstrom syndrome; spectral domain optical coherence tomography (OCT); cyliopathies; retinal immaturity
19.  Whole-Exome Sequencing Identifies ALMS1, IQCB1, CNGA3, and MYO7A Mutations in Patients with Leber Congenital Amaurosis 
Human mutation  2011;32(12):1450-1459.
It has been well documented that mutations in the same retinal disease gene can result in different clinical phenotypes due to difference in the mutant allele and/or genetic background. To evaluate this, a set of consanguineous patient families with Leber congenital amaurosis (LCA) that do not carry mutations in known LCA disease genes was characterized through homozygosity mapping followed by targeted exon/whole-exome sequencing to identify genetic variations. Among these families, a total of five putative disease-causing mutations, including four novel alleles, were found for six families. These five mutations are located in four genes, ALMS1, IQCB1, CNGA3, and MYO7A. Therefore, in our LCA collection from Saudi Arabia, three of the 37 unassigned families carry mutations in retinal disease genes ALMS1, CNGA3, and MYO7A, which have not been previously associated with LCA, and 3 of the 37 carry novel mutations in IQCB1, which has been recently associated with LCA. Together with other reports, our results emphasize that the molecular heterogeneity underlying LCA, and likely other retinal diseases, may be highly complex. Thus, to obtain accurate diagnosis and gain a complete picture of the disease, it is essential to sequence a larger set of retinal disease genes and combine the clinical phenotype with molecular diagnosis.
doi:10.1002/humu.21587
PMCID: PMC3943164  PMID: 21901789
Leber congenital amaurosis; LCA; whole-exome sequencing; SNP; padlock
20.  A Homolog of CcpA Mediates Catabolite Control in Listeria monocytogenes but Not Carbon Source Regulation of Virulence Genes 
Journal of Bacteriology  1998;180(23):6316-6324.
Readily utilizable sugars down-regulate virulence gene expression in Listeria monocytogenes, which has led to the proposal that this regulation may be an aspect of global catabolite regulation (CR). We recently demonstrated that the metabolic enzyme α-glucosidase is under CR in L. monocytogenes. Here, we report the cloning and characterization from L. monocytogenes of an apparent ortholog of ccpA, which encodes an important mediator of CR in several low-G+C-content gram-positive bacteria. L. monocytogenes ccpA (ccpALm) is predicted to encode a 335-amino-acid protein with nearly 65% identity to the gene product of Bacillus subtilis ccpA (ccpABs). Southern blot analysis with a probe derived from ccpALm revealed a single strongly hybridizing band and also a second band of much lower intensity, suggesting that there may be other closely related sequences in the L. monocytogenes chromosome, as is the case in B. subtilis. Disruption of ccpALm resulted in the inability of the mutant to grow on glucose-containing minimal medium or increase its growth rate in the presence of preferred sugars, and it completely eliminated CR of α-glucosidase activity in liquid medium. However, α-glucosidase activity was only partially relieved from CR on solid medium. These results suggest that ccpA is an important element of carbon source regulation in L. monocytogenes. Nevertheless, utilizable sugars still down-regulate the expression of hly, which encodes the virulence factor hemolysin, in a ccpALm mutant, indicating that CcpA is not involved in carbon source regulation of virulence genes.
PMCID: PMC107718  PMID: 9829942
21.  Population Genomic Analysis of ALMS1 in Humans Reveals a Surprisingly Complex Evolutionary History 
Molecular Biology and Evolution  2009;26(6):1357-1367.
Mutations in the human gene ALMS1 result in Alström Syndrome, which presents with early childhood obesity and insulin resistance leading to Type 2 diabetes. Previous genomewide scans for selection in the HapMap data based on linkage disequilibrium and population structure suggest that ALMS1 was subject to recent positive selection. Through a detailed population genomic analysis of existing genomewide data sets and new resequencing data obtained in geographically diverse populations, we find that the signature of selection at ALMS1 is considerably more complex than what would be expected for an idealized model of a selective sweep acting on a newly arisen advantageous mutation. Specifically, we observed three highly divergent and globally dispersed haplogroups, two of which carry a set of seven derived nonsynonymous single nucleotide polymorphisms that are nearly fixed in Asian populations. Our data suggest that the interaction of human demographic history and positive selection on standing variation in Eurasian populations approximately 15 thousand years ago parsimoniously explains the spectrum of extant ALMS1 variation. These results provide new insights into the evolutionary history of ALMS1 in humans and suggest that selective events identified in genomewide scans may be more complex than currently appreciated.
doi:10.1093/molbev/msp045
PMCID: PMC2734137  PMID: 19279085
ALMS1; positive selection; standing variation
22.  Targeted high-throughput sequencing for diagnosis of genetically heterogeneous diseases: efficient mutation detection in Bardet-Biedl and Alström Syndromes 
Journal of Medical Genetics  2012;49(8):502-512.
Background
Bardet-Biedl syndrome (BBS) is a pleiotropic recessive disorder that belongs to the rapidly growing family of ciliopathies. It shares phenotypic traits with other ciliopathies, such as Alström syndrome (ALMS), nephronophthisis (NPHP) or Joubert syndrome. BBS mutations have been detected in 16 different genes (BBS1-BBS16) without clear genotype-to-phenotype correlation. This extensive genetic heterogeneity is a major concern for molecular diagnosis and genetic counselling. While various strategies have been recently proposed to optimise mutation detection, they either fail to detect mutations in a majority of patients or are time consuming and costly.
Method
We tested a targeted exon-capture strategy coupled with multiplexing and high-throughput sequencing on 52 patients: 14 with known mutations as proof-of-principle and 38 with no previously detected mutation. Thirty genes were targeted in total including the 16 BBS genes, the 12 known NPHP genes, the single ALMS gene ALMS1 and the proposed modifier CCDC28B.
Results
This strategy allowed the reliable detection of causative mutations (including homozygous/heterozygous exon deletions) in 68% of BBS patients without previous molecular diagnosis and in all proof-of-principle samples. Three probands carried homozygous truncating mutations in ALMS1 confirming the major phenotypic overlap between both disorders. The efficiency of detecting mutations in patients was positively correlated with their compliance with the classical BBS phenotype (mutations were identified in 81% of ‘classical’ BBS patients) suggesting that only a few true BBS genes remain to be identified. We illustrate some interpretation problems encountered due to the multiplicity of identified variants.
Conclusion
This strategy is highly efficient and cost effective for diseases with high genetic heterogeneity, and guarantees a quality of coverage in coding sequences of target genes suited for diagnosis purposes.
doi:10.1136/jmedgenet-2012-100875
PMCID: PMC3436454  PMID: 22773737
Targeted sequencing; ciliopathies; Bardet-Biedl syndrome; multiplexing; diagnosis
23.  Polyomavirus late leader region serves an essential spacer function necessary for viability and late gene expression. 
Journal of Virology  1986;58(2):417-425.
All three polyomavirus late mRNAs contain multiple tandem copies of the same nontranslated 57-nucleotide sequence, the late leader, at their 5' ends. We show here that a polyoma variant (ALM) lacking 48 central bases of the 57-base leader unit is nonviable by plaque assay and by a new method for testing virus viability, an immunofluorescence burst assay. ALM is, however, unaffected in early gene expression as measured both by indirect immunofluorescence of large T antigen and by transformation levels of rat F-111 cells. DNA replication in mouse cells is also as wild type, and the defect in ALM is complemented by an early-defective helper virus DNA. ALM does not make detectable levels of late viral proteins and is minimally 200-fold depressed in the accumulation of cytoplasmic polyadenylated late RNA. When the deleted leader sequence of ALM is replaced by a variety of procaryotic sequences, viability almost always returns. Some of the substituted leader variants produce plaques with the same apparent kinetics as wild-type viral DNA. The indication is that the sequence of the polyoma late leader is not important for late gene expression but that it has an essential spacer function on the RNA or DNA level. This spacer function is apparently necessary for late viral RNA transcription, processing, or stability.
Images
PMCID: PMC252927  PMID: 3009856
24.  Alstrom syndrome (OMIM 203800): a case report and literature review 
Background
Alstrom syndrome (AS) is a rare autosomal recessive disease characterized by multiorgan dysfunction. The key features are childhood obesity, blindness due to congenital retinal dystrophy, and sensorineural hearing loss. Associated endocrinologic features include hyperinsulinemia, early-onset type 2 diabetes, and hypertriglyceridemia. Thus, AS shares several features with the common metabolic syndrome, namely obesity, hyperinsulinemia, and hypertriglyceridemia. Mutations in the ALMS1 gene have been found to be causative for AS with a total of 79 disease-causing mutations having been described.
Case presentation
We describe the case of a 27-year old female from an English (Caucasian) kindred. She had been initially referred for hypertriglyceridemia, but demonstrated other features suggestive of AS, including blindness, obesity, type 2 diabetes, renal dysfunction, and hypertension. DNA analysis revealed that she is a compound heterozygote with two novel mutations in the ALMS1 gene – H3882Y and V424I. Examination of her family revealed that her phenotypically unaffected mother and younger sister also had heterozygous mutations in the ALMS1 gene. In addition to presenting these novel molecular findings for AS, we review the clinical and genetic features of AS in the context of our case.
Conclusion
Two novel mutations in the ALMS1 gene causative for AS have been reported here, thereby increasing the number of reported mutations to 81 and providing a wider basis for mutational screening among affected individuals.
doi:10.1186/1750-1172-2-49
PMCID: PMC2266715  PMID: 18154657
25.  The progression from obesity to type 2 diabetes in Alström syndrome 
Pediatric Diabetes  2011;13(1):59-67.
Background
Alström syndrome (ALMS) is a rare autosomal recessive monogenic disease associated with obesity, hyperinsulinemia and alterations of glucose metabolism that often lead to the development of type 2 diabetes in a young age.
Objective
Relationship between weight and metabolism has been studied in a group of ALMS patients and matched controls.
Research design and methods
Fifteen ALMS patients (8 M, 7 F, aged 3-51 yrs) were compared in a cross-sectional study with an age- and weight-matched control population. Anthropometric parameters, fat mass, glucose and insulin secretion in basal and dynamic (OGTT) conditions were measured. Further anthropometric and body composition data were obtained from an International group of 27 ALMS patients (13 M, 14 F, age range: 4-29 yrs).
Results
In ALMS we observed an inverse correlation between age and SDS for height, weight and BMI. The OGTT glycemic curves of ALMS subjects were similar to those of age-matched controls, while insulin response was clearly greater. In ALMS individuals the insulin response showed a reduction with age. We documented pathologic values of the derived indices HOMA-IR, ISI, HOMA%β cell and Insulinogenic Index in ALMS, but unlike the insulin-resistance indices, the beta-cell function indices showed a significant reduction with age.
Conclusions
In ALMS the progression from the early onset obesity towards the impaired fasting glucose or IGT and overt diabetes is mostly due to a progressive failure of β-cell insulin secretion without any further worsening of insulin resistance with age, even in the presence of weight reduction.
doi:10.1111/j.1399-5448.2011.00789.x
PMCID: PMC3345208  PMID: 21722283
Alström syndrome; ALMS1; obesity; diabetes; insulin resistance

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