Familial Mediterranean Fever (FMF), inherited in an autosomal recessive manner, is a systemic auto-inflammatory disorder characterized by recurrent attacks of fever with peritonitis, pleuritis, synovitis and erysipeloid rash. The marenostrin-encoding fever gene (MEFV), located on chromosome 16p13.3, is the only gene in which mutations are currently known to cause FMF. To correlate specific genotypes with adverse phenotypes of affected populations residing in the Western United States, a retrospective case series review was conducted of all MEFV gene mutation testing completed at UCLA Clinical Molecular Diagnostic Laboratory between February 2002 and February 2012, followed by clinical chart review of all subjects who either have a single or double mutation. All 12 common mutations in the MEFV gene were analyzed and the M694V variant was found to be associated with an adverse FMF clinical outcome in the Armenian-American population, manifested by earlier onset of disease, increased severity of disease, and renal amyloidosis.
Disorders of sex development (DSD) are rare disorders in which there is discordance between chromosomal, gonadal, and phenotypic sex. Only a minority of patients clinically diagnosed with DSD obtains a molecular diagnosis, leaving a large gap in our understanding of the prevalence, management, and outcomes in affected patients. We created a novel DSD-genetic diagnostic tool, in which sex development genes are captured using RNA probes and undergo massively parallel sequencing. In the pilot group of 14 patients, we determined sex chromosome dosage, copy number variation, and gene mutations. In the patients with a known genetic diagnosis (obtained either on a clinical or research basis), this test identified the molecular cause in 100% (7/7) of patients. In patients in whom no molecular diagnosis had been made, this tool identified a genetic diagnosis in two of seven patients. Targeted sequencing of genes representing a specific spectrum of disorders can result in a higher rate of genetic diagnoses than current diagnostic approaches. Our DSD diagnostic tool provides for first time, in a single blood test, a comprehensive genetic diagnosis in patients presenting with a wide range of urogenital anomalies.
endocrinology; genetic testing; high-throughput; DNA sequencing; sexual development
Bardet–Biedl syndrome (BBS) is a rare pediatric ciliopathy characterized by marked clinical variability and extensive genetic heterogeneity. Typical diagnosis of BBS is secured at a median of 9 years of age, and sometimes well into adolescence. Here, we report a patient in whom prenatal detection of increased nuchal fold, enlarged echogenic kidneys, and polydactyly prompted us to screen the most commonly mutated genes in BBS and the phenotypically and genetically overlapping ciliopathy, Meckel–Gruber syndrome (MKS). We identified the common Met390Arg mutation in BBS1 in compound heterozygosity with a novel intronic variant of unknown significance (VUS). Testing of mRNA harvested from primary foreskin fibroblasts obtained shortly after birth revealed the VUS to induce a cryptic splice site, which in turn led to a premature termination and mRNA degradation. To our knowledge, this is the earliest diagnosis of BBS in the absence of other affected individuals in the family, and exemplifies how combining clinical assessment with genetic and timely assays of variant pathogenicity can inform clinical diagnosis and assist with patient management in the prenatal and neonatal setting.
Bardet–Biedl syndrome; ciliopathy; prenatal; ultrasound; variant functional analysis
Women with the fragile X mental retardation 1 (FMR1) premutation often have concerns about neurological and medical problems, as they become older and if their fathers experience fragile X-associated tremor/ataxia syndrome (FXTAS). We therefore determined the prevalence of these problems in 110 daughters of men with FXTAS [mean age of 44.8 years (SD 8.2)]. We compared them with 43 female controls with normal FMR1 alleles [mean age of 43.8 years (SD 8.1)] and 36 premutation carrier daughters of parents with the premutation, but without FXTAS [mean age of 43.5 years (SD 7.7)]. Overall, daughters of men with FXTAS have a higher prevalence of neurological symptoms including tremor, balance problems, memory problems, and dizziness, menopausal symptoms, and psychiatric involvement including sleep problems and anxiety when compared with non-carrier female controls. Reported balance problems and menopausal symptoms were significantly higher in daughters of men with FXTAS than in carrier daughters of parents without FXTAS, suggesting the potential influence of background gene effects. Therefore, neurological, psychological and gynecological surveillance should be warranted to better provide appropriate counseling, management and care for daughters of men with FXTAS. Biological markers of additional gene effects that predispose individuals with the premutation to FXTAS need to be developed.
anxiety; depression; fragile X; FXTAS; POI
Diabetes is a disease which could be treated more effectively with a better understanding of pancreas development. This review examines the role of master regulator genes driving crucial steps in pancreas development, from foregut specification to differentiation of the five endocrine cell types. The roles of Pdx1, Ptf1a, and Ngn3 are particularly examined as they are both necessary and sufficient for promoting pancreatic cell fates (Pdx1, Ptf1a) and endocrine cell development (Ngn3). The roles of Arx and Pax4 are studied as they compose part of the regulatory mechanism balancing development of different types of endocrine cells within the iselts and promote the development of α/PP and β/δ cell progenitors, respectively. The roles of the aforementioned genes, and the consequences of misexpression of them for functionality of the pancreas, are examined through recent studies in model organisms, particularly Xenopus and zebrafish. Recent developments in cell replacement therapy research are also covered, concentrating on stem cell research (coaxing both adult and embryonic stem cells towards a β cell fate) and transdifferentiation (generating β cells from other differentiated cell types).
cell replacement therapy; Ngn3; Pancreas; Pdx1; Ptf1a; stem cells; transdifferentiation; Xenopus; zebrafish
The Ehlers-Danlos syndromes (EDS) form a clinically and genetically heterogeneous group of inherited connective-tissue disorders characterized by joint hypermobility, tissue fragility and skin abnormalities. Six subtypes have been well characterized based on clinical features and molecular genetic abnormalities. The arthrochalasia type EDS (formerly type VIIa and VIIb) is characterized by severe generalized joint hypermobility with multiple dislocations including congenital bilateral dislocation of the hips, muscular hypotonia and distinct dysmorphic features. The diagnosis of the arthrochalasia type EDS is of importance in the neonatal period because of consequences of physical disability in later life. However, the differential diagnosis may be difficult because of overlap with other hypermobility syndromes. In addition, the significant hypotonia may direct the physician towards various neuromuscular diagnoses. As patients get older, the hypotonia decreases and facial features become less distinct. In this report we describe seven patients at different ages. Timing of diagnosis varied from prenatal life to adult age. The diagnosis of EDS type VII was confirmed by biochemical studies or mutation analysis showing characteristic mutations in COL1A1 and COL1A2. These mutations result in skipping of exon 6, which leads to defective collagen synthesis. For physicians treating patients with EDS type VII, achieving mobility for the patient is the greatest challenge and it may be impossible due to recurrent dislocations of nearly all joints in severe cases.
Ehlers-Danlos Syndrome (EDS); the arthrochalasia type EDS; EDS type VII; hypermobility; (sub)luxations
VCP disease associated with Inclusion body myopathy, Paget disease of the bone and frontotemporal dementia is a progressive autosomal dominant disorder caused by mutations in Valosin containing protein gene. To establish genotype-phenotype correlations we analyzed clinical and biochemical markers from a database of 190 members in 27 families harboring ten missense mutations. Individuals were grouped into three categories: symptomatic, presymptomatic carriers and non-carriers. The symptomatic families were further divided into ten groups based on their VCP mutations. There was marked intra and inter-familial variation; and significant genotype-phenotype correlations were difficult because of small numbers. Nevertheless when comparing the two most common mutations, R155C mutation was found to be more severe, with earlier onset of myopathy and Paget (p=0.03).
Survival analysis of all subjects revealed an average life span after diagnosis of myopathy and Paget of 18 and 19 years respectively, and after dementia only 6 years. R155C had a reduced survival compared to the R155H mutation (p=0.03). We identified amyotrophic lateral sclerosis (ALS) in thirteen individuals (8.9%) and Parkinson’s disease in five individuals (3%); however there was no genotypic correlation. This study represents the largest dataset of patients with VCP disease and expands our understanding of natural history and provides genotype-phenotype correlations in this unique disease.
amyotrophic lateral sclerosis; frontotemporal dementia; genotype-phenotype; inclusion body myopathy; Paget’s disease of bone; valosin containing protein
The genetic mechanisms driving normal brain development remain largely unknown. We performed genomic and immunohistochemical characterization of a novel, fatal human phenotype including extreme microcephaly with cerebral growth arrest at 14-18 weeks gestation in three full sisters born to healthy, non-consanguineous parents. Analysis of index cases and parents included familial exome sequencing, karyotyping, and genome-wide SNP array. From proband, control and unrelated microcephalic fetal cortical tissue, we compared gene expression of RNA and targeted immunohistochemistry. Each daughter was homozygous for a rare, non-synonymous, deleterious variant in the MKL2 gene and heterozygous for a private 185 kb deletion on the paternal allele, upstream and in cis with his MKL2 variant allele, eliminating 24 CArG transcription factor binding sites and MIR4718. MKL1 was underexpressed in probands. Dysfunction of MKL2 and its transcriptional coactivation partner, SRF, was supported by a decrease in gene and protein expression of PCTAIRE1, a downstream target of MKL2:SRF heterodimer transcriptional activation, previously shown to result in severe microcephaly in murine models. While disruption of the MKL2:SRF axis has been associated with severe microcephaly and disordered brain development in multiple model systems, the role of this transcription factor complex has not been previously demonstrated in human brain development.
CArG-box binding factor; exome; microcephaly; MKL2; SRF
Premutation alleles (55-200 CGG repeats) of the fragile X mental retardation (FMR1) gene have been linked to various types of clinical involvement ranging from mood and anxiety disorders to immunological disorders and executive function deficits. Carrier females typically have a premutation allele and a normal allele (<55 CGG repeats). Although rare, 7 cases of females that carry two expanded alleles (compound heterozygous premutation) have been reported. Here we report on four members of a family including two compound heterozygous premutation sisters with similar CGG allele sizes, affected with different levels of clinical severity.
The pathogenesis of inherited cataracts of all kinds recapitulates the developmental and cell biology of the lens. Just as each novel mutation provides additional information about the structural or functional biology of the affected gene, each newly identified gene provides insight into the developmental and cellular biology of the lens. The set of genes currently known to be associated with cataract is far from complete, especially for age-related cataract, and there is much additional information to be discovered through further genetic studies.
cataract; genetics; lens; mutations
The enteric nervous system (ENS), the intrinsic innervation of the gastrointestinal tract, is an essential component of the gut neuromusculature and controls many aspects of gut function, including coordinated muscular peristalsis. The ENS is entirely derived from neural crest cells (NCC) which undergo a number of key processes, including extensive migration into and along the gut, proliferation, and differentiation into enteric neurons and glia, during embryogenesis and fetal life. These mechanisms are under the molecular control of numerous signaling pathways, transcription factors, neurotrophic factors and extracellular matrix components. Failure in these processes and consequent abnormal ENS development can result in so-called enteric neuropathies, arguably the best characterized of which is the congenital disorder Hirschsprung disease (HSCR), or aganglionic megacolon. This review focuses on the molecular and genetic factors regulating ENS development from NCC, the clinical genetics of HSCR and its associated syndromes, and recent advances aimed at improving our understanding and treatment of enteric neuropathies.
enteric nervous system; Hirschsprung disease; enteric neuropathies; neural crest cells; RET
Depression during pregnancy can have serious consequences for families. Indications of fetal aneuploidy can induce maternal stress, a risk factor for depression. Few studies have assessed symptoms of depression in pregnant women soon after they receive results indicating increased risk for fetal aneuploidy.
We compared symptoms of depression in women who had increased risks for fetal aneuploidy with two other groups of pregnant women at similar gestational ages: Controls, and women taking antidepressant medication (MEDS).
81 women attending the BC Medical Genetics Programme (MG) regarding positive maternal serum screens or ultrasound soft marker findings completed the Edinburgh Postnatal Depression Scale (EPDS). Control (n=41) and MEDS (n=41) groups were recruited from the community or the BC Reproductive Mental Health program. A threshold score of 12 on the EPDS was used to calculate percentages of women likely to be depressed. Mean EPDS scores were compared using ANOVA, followed by post-hoc tests.
In the Control, MG, and MEDS groups, 2.4%, 35%, and 52.4% of women, respectively, scored above 12. Mean EPDS score was significantly higher in the MG group than in the Control group (p<.0001).
These results suggest a place for depression screening in prenatal genetic counselling.
PMID: 18637940 CAMSID: cams3083
DEPRESSION; FETAL ANEUPLOIDY; GENETIC COUNSELLING; MATERNAL SERUM SCREEN; MOOD; PREGNANCY; PRENATAL; ULTRASOUND SOFT MARKER
Germline mutations in PMS2 are associated with Lynch syndrome (LS), the most common known cause of hereditary colorectal cancer. Mutation detection in PMS2 has been difficult due to the presence of several pseudogenes, but a custom-designed long-range PCR strategy now allows adequate mutation detection. Many mutations are unique. However some mutations are observed repeatedly, across individuals not known to be related, due to the mutation being either recurrent, arising multiple times de novo at hot spots for mutations, or of founder origin, having occurred once in an ancestor. Previously, we observed 36 distinct mutations in a sample of 61 independently ascertained Caucasian probands of mixed European background with PMS2 mutations. Eleven of these mutations were detected in more than one individual not known to be related and of these, six were detected more than twice. These six mutations accounted for 31 (51%) ostensibly unrelated probands. Here we performed genotyping and haplotype analysis in four mutations observed in multiple probands and found two (c.137G>T and exon 10 deletion) to be founder mutations, one (c.903G>T) a probable founder, and one (c.1A>G) where founder mutation status could not be evaluated. We discuss possible explanations for the frequent occurrence of founder mutations in PMS2.
colon cancer; founder mutation; genetic predisposition; PMS2
This study examined colonoscopy adherence and attitudes towards colorectal cancer (CRC) screening in individuals who underwent Lynch syndrome genetic counseling and testing.
We evaluated changes in colonoscopy adherence and CRC screening attitudes in 78 cancer-unaffected relatives of Lynch syndrome mutation carriers before pre-test genetic counseling (baseline) and at 6 and 12 months post-disclosure of test results (52 mutation-negative, 26 mutation-positive).
While both groups were similar at baseline, at 12 months post-disclosure, a greater number of mutation-positive individuals had had a colonoscopy compared with mutation-negative individuals. From baseline to 12 months post-disclosure, the mutation-positive group demonstrated an increase in mean scores on measures of colonoscopy commitment, self-efficacy, and perceived benefits of CRC screening, and a decrease in mean scores for perceived barriers to CRC screening. Mean scores on colonoscopy commitment decreased from baseline to 6 months in the mutation-negative group.
Adherence to risk-appropriate guidelines for CRC surveillance improved after genetic counseling and testing for Lynch syndrome. Mutation-positive individuals reported increasingly positive attitudes toward CRC screening after receiving genetic test results, potentially reinforcing longer term colonoscopy adherence.
Lynch syndrome; colorectal cancer screening; genetic counseling and testing; colonoscopy commitment; benefits of and barriers to screening
The advent of whole-exome next-generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical application of WES has remained relatively unexplored. We describe our experience with WES as a diagnostic tool in a three-year old female patient with a two-year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work-up. WES was performed on the proband and her two parents. Parental exome data was used to filter de novo genomic events in the proband and suspected mutations were confirmed using di-deoxy sequencing. WES revealed a de novo non-synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband’s original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future.
Hypokalemic periodic paralysis; CACNA1S; next generation sequencing; hypotonia
Autosomal recessive retinitis pigmentosa (arRP) is a clinically and genetically heterogeneous retinal disease that causes blindness. Our purpose was to identify the causal gene, describe the phenotype and delineate the mutation spectrum in a consanguineous Quebec arRP family. We performed Arrayed Primer Extension (APEX) technology to exclude ~500 arRP mutations in ~20 genes. Homozygosity mapping [single nucleotide polymorphism (SNP) genotyping] identified 10 novel significant homozygous regions. We performed next generation sequencing and whole exome capture. Sanger sequencing provided cosegregation. We screened another 150 retinitis pigmentosa (RP) and 200 patients with Senior-Løken Syndrome (SLS). We identified a novel missense mutation in WDR19, c.2129T>C which lead to a p.Leu710Ser. We found the same mutation in a second Quebec arRP family. Interestingly, two of seven affected members of the original family developed ‘sub-clinical’ renal cysts. We hypothesized that more severe WDR19 mutations may lead to severe ciliopathies and found seven WDR19 mutations in five SLS families. We identified a new gene for both arRP and SLS. WDR19 is a ciliary protein associated with the intraflagellar transport machinery. We are currently investigating the full extent of the mutation spectrum. Our findings are crucial in expanding the understanding of childhood blindness and identifying new genes.
childhood blindness; IFT144; IFT-A; nephronophtisis; photoreceptors; retinal degeneration; retinitis pigmentosa; Senior-Løken syndrome; WDR19
The introduction of clinical genome-wide sequencing raises complex issues regarding the management of incidental findings. However, there is a lack of empirical studies assessing views of providers involved in potential disclosure of such findings. In an anonymous survey of 279 clinical genetics professionals, we found that the vast majority agreed they were interested in knowing about clinically actionable incidental findings in themselves (96%) and their child (99%), and they reported that these types of findings should be disclosed in adult (96%) and minor (98%) patients. Approximately three-fourths agreed they were personally interested in knowing about an adult-onset clinically actionable disease (78%), and a childhood-onset non-clinically actionable disease (75%) in their child. A similar percentage of participants (70%) felt these two types of findings should be disclosed to patients. Forty-four percent wanted to know about an incidental finding that indicates an adult-onset non-clinically actionable condition in themselves and 31% wanted to know about this type of information in their child. Findings from this study revealed participant views highly dependent on clinical actionability. Further research is needed with a broader population of geneticists to increase generalizability, and with diverse patients to assess their perspectives about results disclosure from clinical sequencing.
Clinical genetics; ethics; genetics professionals; genomic sequencing; incidental findings; policy; return of results; secondary findings; whole genome sequencing
Chromosomal microarray analysis (CMA) has improved the diagnostic rate of genomic disorders in pediatric populations, but can produce uncertain and unexpected findings. This paper explores clinicians’ perspectives and identifies challenges in effectively interpreting results and communicating with families about CMA. Responses to an online survey were obtained from 40 clinicians who had ordered CMA. Content included practice characteristics and perceptions, and queries about a hypothetical case involving uncertain and incidental findings. Data were analyzed using non-parametric statistical tests. Clinicians’ comfort levels differed significantly for explaining uncertain, abnormal, and normal CMA results, with lowest levels for uncertain results. Despite clinical guidelines recommending informed consent, many clinicians did not consider it pertinent to discuss the potential for CMA to reveal information concerning biological parentage or predisposition to late-onset disease, in a hypothetical case. Many non-genetics professionals ordering CMA did not feel equipped to interpret the results for patients, and articulated needs for education and access to genetics professionals. This exploratory study highlights key challenges in the practice of genomic medicine, and identifies needs for education, disseminated practice guidelines, and access to genetics professionals, especially when dealing with uncertain or unexpected findings.
Cytogenomics; incidental findings; uncertainty; health communication; pediatrics; genomic medicine; genetic counseling
Dyskeratosis congenita (DC) is a telomere-biology disorder characterized by a mucocutaneous triad, aplastic anemia, and predisposition to cancer. Mutations in a narrow segment of TINF2 exon 6 have been recognized to cause often-severe DC that is either sporadic or autosomal dominant. We describe three children with very early presentations of DC, including one with the severe variant known as Revesz syndrome. Whereas most TINF2 mutations reported to date are missense changes, each of our patients carried a novel heterozygous nonsense or frameshift mutation, revealing a new 5’ boundary to the affected gene segment in patients with DC. Examination of patient-derived lymphoblastoid cell lines revealed stable expression of the predicted truncated TIN2 proteins. In co-immunoprecipitation assays, the ability of a truncation mutant to interact with TRF1 was severely impaired, whereas the ability of the most common DC-associated mutant was much less affected. This suggests that disruption of TIN2-TRF1 interaction may contribute to the severe clinical phenotype observed in the context of the TIN2 truncation mutation but is unlikely to be the primary cause of telomere shortening associated with the more prevalent TIN2 missense mutations. Telomere flow-FISH analysis of one pedigree demonstrated the dramatic effect a de novo nonsense TINF2 mutation had on telomere length in early development. These cases underscore the severe manifestations of truncating TINF2 mutations.
Aplastic anemia; bone marrow failure; dyskeratosis congenita; Revesz syndrome; TIN2; TINF2; telomere
Despite an increase in direct-to-consumer (DTC) genetic testing, little is known about how variations in website content might alter consumer behavior. We evaluated the impact of risk information provision on women’s attitudes about DTC BRCA testing. We conducted a randomized experiment; women viewed a “mock” BRCA testing website without (control group: CG) or with information on the potential risks of DTC testing (RG; framed two ways: unattributed information [UR] and information presented by experts [ER]). 767 women participated; mean age was 37 years, mean education was 15 years, and 79% of subjects were white. Women in the RG had less positive beliefs about DTC testing (mean RG=23.8, CG=25.2; p=0.001), lower intentions to get tested (RG= 2.8, CG= 3.1; p=0.03), were more likely to prefer clinic-based testing (RG=5.1, CG=4.8; p=0.03) and to report that they had seen enough risk information (RG=5.3, CG= 4.7; p<0.001). UR and ER exposure produced similar effects. Effects did not differ for women with or without a personal/family history of breast/ovarian cancer. Exposing women to the potential risks of DTC BRCA testing altered their beliefs, preferences, and intentions. Risk messages appear to be salient to women irrespective of their chance of having a BRCA mutation.
communication; direct-to-consumer; BRCA; informed consent; cancer
PMID: 19650864 CAMSID: cams3649