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1.  In vivo Modeling Implicates APOL1 in Nephropathy: Evidence for Dominant Negative Effects and Epistasis under Anemic Stress 
PLoS Genetics  2015;11(7):e1005349.
African Americans have a disproportionate risk for developing nephropathy. This disparity has been attributed to coding variants (G1 and G2) in apolipoprotein L1 (APOL1); however, there is little functional evidence supporting the role of this protein in renal function. Here, we combined genetics and in vivo modeling to examine the role of apol1 in glomerular development and pronephric filtration and to test the pathogenic potential of APOL1 G1 and G2. Translational suppression or CRISPR/Cas9 genome editing of apol1 in zebrafish embryos results in podocyte loss and glomerular filtration defects. Complementation of apol1 morphants with wild-type human APOL1 mRNA rescues these defects. However, the APOL1 G1 risk allele does not ameliorate defects caused by apol1 suppression and the pathogenicity is conferred by the cis effect of both individual variants of the G1 risk haplotype (I384M/S342G). In vivo complementation studies of the G2 risk allele also indicate that the variant is deleterious to protein function. Moreover, APOL1 G2, but not G1, expression alone promotes developmental kidney defects, suggesting a possible dominant-negative effect of the altered protein. In sickle cell disease (SCD) patients, we reported previously a genetic interaction between APOL1 and MYH9. Testing this interaction in vivo by co-suppressing both transcripts yielded no additive effects. However, upon genetic or chemical induction of anemia, we observed a significantly exacerbated nephropathy phenotype. Furthermore, concordant with the genetic interaction observed in SCD patients, APOL1 G2 reduces myh9 expression in vivo, suggesting a possible interaction between the altered APOL1 and myh9. Our data indicate a critical role for APOL1 in renal function that is compromised by nephropathy-risk encoding variants. Moreover, our interaction studies indicate that the MYH9 locus is also relevant to the phenotype in a stressed microenvironment and suggest that consideration of the context-dependent functions of both proteins will be required to develop therapeutic paradigms.
Author Summary
African Americans have a disproportionate risk for developing chronic kidney disease compared to European Americans. Previous studies have identified a region on chromosome 22 containing two genes, MYH9 and APOL1, which likely accounts for nearly all of this difference. Previous reports provided strong statistical evidence implicating APOL1 as the major contributor to nephropathy risk in African Americans, driven by two coding variants, termed G1 and G2. However, other groups still report statistical evidence for MYH9 association in kidney disease, and animal models have demonstrated biological relevance for MYH9 function in the kidney. Here, we show that suppressing apol1 in zebrafish embryos results in perturbed kidney function. Importantly, using this in vivo assay, we show that the G1 variant appears to cause a loss of APOL1 function, while the G2 variant results in an altered protein that may be acting antagonistically in the presence of normal APOL1. We also report a genetic interaction between apol1 and myh9 under anemic stress, which is consistent with our previous findings in sickle cell disease (SCD) nephropathy patients. Finally, we provide functional evidence in vivo that the G2-altered APOL1 may be interacting with MYH9 to confer nephropathy risk.
PMCID: PMC4492502  PMID: 26147622
2.  Rapid and Efficient Generation of Transgene-Free iPSC from a Small Volume of Cryopreserved Blood 
Stem Cell Reviews  2015;11(4):652-665.
Human peripheral blood and umbilical cord blood represent attractive sources of cells for reprogramming to induced pluripotent stem cells (iPSCs). However, to date, most of the blood-derived iPSCs were generated using either integrating methods or starting from T-lymphocytes that have genomic rearrangements thus bearing uncertain consequences when using iPSC-derived lineages for disease modeling and cell therapies. Recently, both peripheral blood and cord blood cells have been reprogrammed into transgene-free iPSC using the Sendai viral vector. Here we demonstrate that peripheral blood can be utilized for medium-throughput iPSC production without the need to maintain cell culture prior to reprogramming induction. Cell reprogramming can also be accomplished with as little as 3000 previously cryopreserved cord blood cells under feeder-free and chemically defined Xeno-free conditions that are compliant with standard Good Manufacturing Practice (GMP) regulations. The first iPSC colonies appear 2–3 weeks faster in comparison to previous reports. Notably, these peripheral blood- and cord blood-derived iPSCs are free of detectable immunoglobulin heavy chain (IGH) and T cell receptor (TCR) gene rearrangements, suggesting they did not originate from B- or T- lymphoid cells. The iPSCs are pluripotent as evaluated by the scorecard assay and in vitro multi lineage functional cell differentiation. Our data show that small volumes of cryopreserved peripheral blood or cord blood cells can be reprogrammed efficiently at a convenient, cost effective and scalable way. In summary, our method expands the reprogramming potential of limited or archived samples either stored at blood banks or obtained from pediatric populations that cannot easily provide large quantities of peripheral blood or a skin biopsy.
Electronic supplementary material
The online version of this article (doi:10.1007/s12015-015-9586-8) contains supplementary material, which is available to authorized users.
PMCID: PMC4493720  PMID: 25951995
Reprogramming; Peripheral blood; Cord blood; Sendai viral vector; Genomic rearrangement; GMP; Cell therapy; iPSC
3.  The Effects of Cyclic Stretch on Gene Transfer in Alveolar Epithelial Cells 
Cyclic stretch has been shown to alter cell physiology, cytoskeletal structure, signal transduction, and gene expression in a variety of cell types. To determine the effects of stretch on the gene transfer process, we compared the transfection efficiencies of human A549 cells grown either statically or exposed to 10% cyclic stretch (Δ surface area) at 60 cycles/min (1 Hz) for 24 hours prior to, and/or after transfection with pEGFP-N1 and pCMV-lux-DTS using lipoplex or electroporation. Stretching the cells prior to transfection had no effect on gene transfer. By contrast, cyclic, but not continuous, stretch applied immediately after transfection for as little as 30 minutes resulted in a 10-fold increase in gene transfer and expression by either transfection technique. These stretch conditions did not result in rupture of the plasma membrane based on the fact that DNA was unable to enter stretched cells unless either an electric field was applied or the DNA was complexed with liposomes. Taken together with the timing of the stretch response and the known effects of stretch on transcription, these findings suggest that cyclic stretch may be altering the intracellular transport of plasmids to increase gene expression.
PMCID: PMC4394637  PMID: 12727118
gene therapy; gene delivery; gene expression; nonviral vectors; plasmid DNA; transfection; lipoplex; electroporation; cyclic stretch
4.  Unique among ciliopathies: primary ciliary dyskinesia, a motile cilia disorder 
F1000Prime Reports  2015;7:36.
Primary ciliary dyskinesia (PCD) is a ciliopathy, but represents the sole entity from this class of disorders that results from the dysfunction of motile cilia. Characterized by respiratory problems appearing in childhood, infertility, and situs defects in ~50% of individuals, PCD has an estimated prevalence of approximately 1 in 10,000 live births. The diagnosis of PCD can be prolonged due to a lack of disease awareness, coupled with the fact that symptoms can be confused with other more common genetic disorders, such as cystic fibrosis, or environmental insults that result in frequent respiratory infections. A primarily autosomal recessive disorder, PCD is genetically heterogeneous with >30 causal genes identified, posing significant challenges to genetic diagnosis. Here, we provide an overview of PCD as a disorder underscored by impaired ciliary motility; we discuss the recent advances towards uncovering the genetic basis of PCD; we discuss the molecular knowledge gained from PCD gene discovery, which has improved our understanding of motile ciliary assembly; and we speculate on how accelerated diagnosis, together with detailed phenotypic data, will shape the genetic and functional architecture of this disorder.
PMCID: PMC4371376  PMID: 25926987
5.  The kinetochore protein, CENPF, is mutated in human ciliopathy and microcephaly phenotypes 
Journal of Medical Genetics  2015;52(3):147-156.
Mutations in microtubule-regulating genes are associated with disorders of neuronal migration and microcephaly. Regulation of centriole length has been shown to underlie the pathogenesis of certain ciliopathy phenotypes. Using a next-generation sequencing approach, we identified mutations in a novel centriolar disease gene in a kindred with an embryonic lethal ciliopathy phenotype and in a patient with primary microcephaly.
Methods and results
Whole exome sequencing data from a non-consanguineous Caucasian kindred exhibiting mid-gestation lethality and ciliopathic malformations revealed two novel non-synonymous variants in CENPF, a microtubule-regulating gene. All four affected fetuses showed segregation for two mutated alleles [IVS5-2A>C, predicted to abolish the consensus splice-acceptor site from exon 6; c.1744G>T, p.E582X]. In a second unrelated patient exhibiting microcephaly, we identified two CENPF mutations [c.1744G>T, p.E582X; c.8692 C>T, p.R2898X] by whole exome sequencing. We found that CENP-F colocalised with Ninein at the subdistal appendages of the mother centriole in mouse inner medullary collecting duct cells. Intraflagellar transport protein-88 (IFT-88) colocalised with CENP-F along the ciliary axonemes of renal epithelial cells in age-matched control human fetuses but did not in truncated cilia of mutant CENPF kidneys. Pairwise co-immunoprecipitation assays of mitotic and serum-starved HEKT293 cells confirmed that IFT88 precipitates with endogenous CENP-F.
Our data identify CENPF as a new centriolar disease gene implicated in severe human ciliopathy and microcephaly related phenotypes. CENP-F has a novel putative function in ciliogenesis and cortical neurogenesis.
PMCID: PMC4345935  PMID: 25564561
Clinical genetics; Molecular genetics; CENPF; Ciliopathy; Microcephaly
6.  Whole Exome Sequencing of a Dominant Retinitis Pigmentosa Family Identifies a Novel Deletion in PRPF31 
Mutations at some retinitis pigmentosa (RP) loci are associated with variable penetrance and expressivity, exacerbating diagnostic challenges. The purpose of this study was to dissect the genetic underpinnings of nonsyndromic RP with variable age of onset in a large Mexican family.
We ascertained members of a large, multigenerational pedigree using a complete ophthalmic examination. We performed whole exome sequencing on two affected first cousins, an obligate carrier, and a married-in spouse. Confirmatory sequencing of candidate variants was performed in the entire pedigree, as well as genotyping and mRNA studies to investigate expression changes in the causal locus.
We identified a 14–base pair (bp) deletion in PRPF31, a gene implicated previously in autosomal dominant (ad) RP. The mutation segregated with the phenotype of all 10 affected females, but also was present in six asymptomatics (two females and four males). Studies in patient cells showed that the penetrance/expressivity of the PRPF31 deletion allele was concordant with the expression levels of wild-type message. However, neither the known PRPF31 modulators nor cis-eQTLs within 1 Mb of the locus could account for the variable expression of message or the clinical phenotype.
We have identified a novel 14-bp deletion in PRPF31 as the genetic driver of adRP in a large Mexican family that exhibits nonpenetrance and variable expressivity, known properties of this locus. However, our studies intimate the presence of additional loci that can modify PRPF31 expression.
Mutations in PRPF31 are known to cause autosomal dominant retinitis pigmentosa frequently hallmarked by incomplete penetrance. Genetic and functional studies intimate that hitherto unknown modulators may be contributing to this phenomenon.
PMCID: PMC3979517  PMID: 24595387
retinitis pigmentosa; genetic diseases; autosomal dominant; PRPF31; exome sequencing
7.  Whole exome resequencing distinguishes cystic kidney diseases from phenocopies in renal ciliopathies 
Kidney international  2013;85(4):880-887.
Rare single-gene disorders cause chronic disease. However, half of the 6,000 recessive single gene causes of disease are still unknown. Because recessive disease genes can illuminate, at least in part, disease pathomechanism, their identification offers direct opportunities for improved clinical management and potentially treatment. Rare diseases comprise the majority of chronic kidney disease (CKD) in children but are notoriously difficult to diagnose. Whole exome resequencing facilitates identification of recessive disease genes. However, its utility is impeded by the large number of genetic variants detected. We here overcome this limitation by combining homozygosity mapping with whole exome resequencing in 10 sib pairs with a nephronophthisis-related ciliopathy, which represents the most frequent genetic cause of CKD in the first three decades of life. In 7 of 10 sib-ships with a histologic or ultrasonographic diagnosis of nephronophthisis-related ciliopathy we detect the causative gene. In six sib-ships we identify mutations of known nephronophthisis-related ciliopathy genes, while in two additional sib-ships we found mutations in the known CKD-causing genes SLC4A1 and AGXT as phenocopies of nephronophthisis-related ciliopathy. Thus whole exome resequencing establishes an efficient, non-invasive approach towards early detection and causation-based diagnosis of rare kidney diseases. This approach can be extended to other rare recessive disorders, thereby providing accurate diagnosis and facilitating the study of disease mechanisms.
PMCID: PMC3972265  PMID: 24257694
8.  In Vivo Modeling of the Morbid Human Genome using Danio rerio 
Here, we present methods for the development of assays to query potentially clinically significant nonsynonymous changes using in vivo complementation in zebrafish. Zebrafish (Danio rerio) are a useful animal system due to their experimental tractability; embryos are transparent to enable facile viewing, undergo rapid development ex vivo, and can be genetically manipulated.1 These aspects have allowed for significant advances in the analysis of embryogenesis, molecular processes, and morphogenetic signaling. Taken together, the advantages of this vertebrate model make zebrafish highly amenable to modeling the developmental defects in pediatric disease, and in some cases, adult-onset disorders. Because the zebrafish genome is highly conserved with that of humans (~70% orthologous), it is possible to recapitulate human disease states in zebrafish. This is accomplished either through the injection of mutant human mRNA to induce dominant negative or gain of function alleles, or utilization of morpholino (MO) antisense oligonucleotides to suppress genes to mimic loss of function variants. Through complementation of MO-induced phenotypes with capped human mRNA, our approach enables the interpretation of the deleterious effect of mutations on human protein sequence based on the ability of mutant mRNA to rescue a measurable, physiologically relevant phenotype. Modeling of the human disease alleles occurs through microinjection of zebrafish embryos with MO and/or human mRNA at the 1-4 cell stage, and phenotyping up to seven days post fertilization (dpf). This general strategy can be extended to a wide range of disease phenotypes, as demonstrated in the following protocol. We present our established models for morphogenetic signaling, craniofacial, cardiac, vascular integrity, renal function, and skeletal muscle disorder phenotypes, as well as others.
PMCID: PMC3856313  PMID: 23995499
Molecular Biology; Issue 78; Genetics; Biomedical Engineering; Medicine; Developmental Biology; Biochemistry; Anatomy; Physiology; Bioengineering; Genomics; Medical; zebrafish; in vivo; morpholino; human disease modeling; transcription; PCR; mRNA; DNA; Danio rerio; animal model
9.  Validity of covering-up sun-protection habits: Association of observations and self-report 
Few studies have reported the accuracy of measures used to assess sun-protection practices. Valid measures are critical to the internal validity and use of skin cancer control research.
We sought to validate self-reported covering-up practices of pool-goers.
A total of 162 lifeguards and 201 parent/child pairs from 16 pools in 4 metropolitan regions in the United States completed a survey and a 4-day sun-habits diary. Observations of sun-protective behaviors were conducted on two occasions.
Agreement between observations and diaries ranged from slight to substantial, with most values in the fair to moderate range. Highest agreement was observed for parent hat use (κ = 0.58–0.70). There was no systematic pattern of over- or under-reporting among the 3 study groups.
Potential reactivity and a relatively affluent sample are limitations.
There was little over-reporting and no systematic bias, which increases confidence in reliance on verbal reports of these behaviors in surveys and intervention research.
PMCID: PMC3715114  PMID: 19278750
concurrent validity; measurement; observation; self-report assessment; sun protection
10.  KIF7 mutations cause fetal hydrolethalus and acrocallosal syndromes 
Nature genetics  2011;43(6):601-606.
KIF7, the human ortholog of Drosophila Costal2, is a key component of the Hedgehog signaling pathway. Here we report mutations in KIF7 in individuals with hydrolethalus and acrocallosal syndromes, two multiple malformation disorders with overlapping features that include polydactyly, brain abnormalities and cleft palate. Consistent with a role of KIF7 in Hedgehog signaling, we show deregulation of most GLI transcription factor targets and impaired GLI3 processing in tissues from individuals with KIF7 mutations. KIF7 is also a likely contributor of alleles across the ciliopathy spectrum, as sequencing of a diverse cohort identified several missense mutations detrimental to protein function. In addition, in vivo genetic interaction studies indicated that knockdown of KIF7 could exacerbate the phenotype induced by knockdown of other ciliopathy transcripts. Our data show the role of KIF7 in human primary cilia, especially in the Hedgehog pathway through the regulation of GLI targets, and expand the clinical spectrum of ciliopathies.
PMCID: PMC3674836  PMID: 21552264
11.  Evolutionarily Assembled cis-Regulatory Module at a Human Ciliopathy Locus 
Science (New York, N.Y.)  2012;335(6071):966-969.
Neighboring genes are often coordinately expressed within cis-regulatory modules, but evidence that nonparalogous genes share functions in mammals is lacking. Here, we report that mutation of either TMEM138 or TMEM216 causes a phenotypically indistinguishable human ciliopathy, Joubert syndrome. Despite a lack of sequence homology, the genes are aligned in a head-to-tail configuration and joined by chromosomal rearrangement at the amphibian-to-reptile evolutionary transition. Expression of the two genes is mediated by a conserved regulatory element in the noncoding intergenic region. Coordinated expression is important for their interdependent cellular role in vesicular transport to primary cilia. Hence, during vertebrate evolution of genes involved in ciliogenesis, nonparalogous genes were arranged to a functional gene cluster with shared regulatory elements.
PMCID: PMC3671610  PMID: 22282472
12.  Pitchfork Regulates Primary Cilia Dizsassembly and Left-Right Asymmetry 
Developmental cell  2010;19(1):66-77.
A variety of developmental disorders have been associated with ciliary defects, yet the controls that govern cilia disassembly are largely unknown. Here we report a mouse embryonic node gene, which we named Pitchfork (Pifo). Pifo associates with ciliary targeting complexes and accumulates at the basal body during cilia disassembly. Haploinsufficiency causes a unique node cilia duplication phenotype, left-right asymmetry defects, and heart failure. This phenotype is likely relevant in humans, because we identified a heterozygous R80K PIFO mutation in a fetus with situs inversus and cystic liver and kidneys, and in patient with double-outflow right ventricle. We show that PIFO, but not R80K PIFO, is sufficient to activate Aurora A, a protooncogenic kinase that induces cilia retraction, and that Pifo/PIFO mutation causes cilia retraction, basal body liberation, and overreplication defects. Thus, the observation of a disassembly phenotype in vivo provides an entry point to understand and categorize ciliary disease.
PMCID: PMC3671612  PMID: 20643351
13.  The ciliopathies: A transitional model into systems biology of human genetic disease 
The last decade has witnessed an explosion in the identification of genes, mutations in which appear sufficient to cause clinical phenotypes in humans. This is especially true for disorders of ciliary dysfunction in which an excess of 50 causal loci are now known; this discovery was driven in part by an improved understanding of the protein composition of the cilium and the co-occurrence of clinical phenotypes associated with ciliary dysfunction. Despite this progress, the fundamental challenge of predicting phenotype and or clinical progression based on single locus information remains unsolved. Here, we explore how the combinatorial knowledge of allele quality and quantity, an improved understanding of the biological composition of the primary cilium, and the expanded appreciation of the subcellular roles of this organelle can be synthesized to generate improved models that can explain both causality but also variable penetrance and expressivity.
PMCID: PMC3509787  PMID: 22632799
14.  Improved Local and Systemic Anti-Tumor Efficacy for Irreversible Electroporation in Immunocompetent versus Immunodeficient Mice 
PLoS ONE  2013;8(5):e64559.
Irreversible electroporation (IRE) is a non-thermal focal ablation technique that uses a series of brief but intense electric pulses delivered into a targeted region of tissue, killing the cells by irrecoverably disrupting cellular membrane integrity. This study investigates if there is an improved local anti-tumor response in immunocompetent (IC) BALB/c versus immunodeficient (ID) nude mice, including the potential for a systemic protective effect against rechallenge. Subcutaneous murine renal carcinoma tumors were treated with an IRE pulsing protocol that used 60% of the predicted voltage required to invoke complete regressions in the ID mice. Tumors were followed for 34 days following treatment for 11 treated mice from each strain, and 7 controls from each strain. Mouse survival based on tumor burden and the progression-free disease period was substantially longer in the treated IC mice relative to the treated ID mice and sham controls for both strains. Treated IC mice were rechallenged with the same cell line 18 days after treatment, where growth of the second tumors was shown to be significantly reduced or prevented entirely. There was robust CD3+ cell infiltration in some treated BALB/C mice, with immunocytes focused at the transition between viable and dead tumor. There was no difference in the low immunocyte presence for untreated tumors, nude mice, and matrigel-only injections in both strains. These findings suggest IRE therapy may have greater therapeutic efficacy in immunocompetent patients than what has been suggested by immunodeficient models, and that IRE may invoke a systemic response beyond the targeted ablation region.
PMCID: PMC3663742  PMID: 23717630
15.  Mutations in LRRC50 Predispose Zebrafish and Humans to Seminomas 
PLoS Genetics  2013;9(4):e1003384.
Seminoma is a subclass of human testicular germ cell tumors (TGCT), the most frequently observed cancer in young men with a rising incidence. Here we describe the identification of a novel gene predisposing specifically to seminoma formation in a vertebrate model organism. Zebrafish carrying a heterozygous nonsense mutation in Leucine-Rich Repeat Containing protein 50 (lrrc50 also called dnaaf1), associated previously with ciliary function, are found to be highly susceptible to the formation of seminomas. Genotyping of these zebrafish tumors shows loss of heterozygosity (LOH) of the wild-type lrrc50 allele in 44.4% of tumor samples, correlating with tumor progression. In humans we identified heterozygous germline LRRC50 mutations in two different pedigrees with a family history of seminomas, resulting in a nonsense Arg488* change and a missense Thr590Met change, which show reduced expression of the wild-type allele in seminomas. Zebrafish in vivo complementation studies indicate the Thr590Met to be a loss-of-function mutation. Moreover, we show that a pathogenic Gln307Glu change is significantly enriched in individuals with seminoma tumors (13% of our cohort). Together, our study introduces an animal model for seminoma and suggests LRRC50 to be a novel tumor suppressor implicated in human seminoma pathogenesis.
Author Summary
Testicular Germ Cell Tumors are frequently occurring tumors, affecting 1 in 500 individuals. Of this diverse group, the subtype seminoma is most prevalent and is the most common tumor type found in men aged 20–40 years of age. In contrast to other frequently occurring tumor types, there is very little information on the genetic components that form risk factors for seminoma. In this study we describe the unexpected finding that zebrafish carrying a heterozygous mutation in the lrrc50/dnaaf1 gene have a high incidence for testicular germ cell tumor formation. Detailed analysis suggests that these tumors resemble human seminoma. We therefore analyzed this gene in a subset of human seminoma samples and recovered mutations that were subsequently demonstrated to prohibit protein function. Seminomas were also previously found in family members of these patients, suggesting that a genetic component is the underlying cause. We thus identified a novel gene that can be considered a risk factor for human seminoma, and we describe an animal model system that is valuable for further seminoma research.
PMCID: PMC3627517  PMID: 23599692
16.  Delta-Like 1 Homolog (Dlk1): A Marker for Rhabdomyosarcomas Implicated in Skeletal Muscle Regeneration 
PLoS ONE  2013;8(4):e60692.
Dlk1, a member of the Epidermal Growth Factor family, is expressed in multiple tissues during development, and has been detected in carcinomas and neuroendocrine tumors. Dlk1 is paternally expressed and belongs to a group of imprinted genes associated with rhabdomyosarcomas but not with other primitive childhood tumors to date. Here, we investigate the possible roles of Dlk1 in skeletal muscle tumor formation. We analyzed tumors of different mesenchymal origin for expression of Dlk1 and various myogenic markers and found that Dlk1 was present consistently in myogenic tumors. The coincident observation of Dlk1 with a highly proliferative state in myogenic tumors led us to subsequently investigate the involvement of Dlk1 in the control of the adult myogenic programme. We performed an injury study in Dlk1 transgenic mice, ectopically expressing ovine Dlk1 (membrane bound C2 variant) under control of the myosin light chain promotor, and detected an early, enhanced formation of myotubes in Dlk1 transgenic mice. We then stably transfected the mouse myoblast cell line, C2C12, with full-length Dlk1 (soluble A variant) and detected an inhibition of myotube formation, which could be reversed by adding Dlk1 antibody to the culture supernatant. These results suggest that Dlk1 is involved in controlling the myogenic programme and that the various splice forms may exert different effects. Interestingly, both in the Dlk1 transgenic mice and the DLK1-C2C12 cells, we detected reduced myostatin expression, suggesting that the effect of Dlk1 on the myogenic programme might involve the myostatin signaling pathway. In support of a relationship between Dlk1 and myostatin we detected reciprocal expression of these two transcripts during different cell cycle stages of human myoblasts. Together our results suggest that Dlk1 is a candidate marker for skeletal muscle tumors and might be involved directly in skeletal muscle tumor formation through a modulatory effect on the myogenic programme.
PMCID: PMC3618045  PMID: 23577150
17.  CCDC39 is required for assembly of inner dynein arms and the dynein regulatory complex and for normal ciliary motility in humans and dogs 
Nature genetics  2010;43(1):72-78.
Primary ciliary dyskinesia (PCD) is an inherited disorder characterized by recurrent infections of the upper and lower respiratory tract, reduced fertility in males and situs inversus in about 50% of affected individuals (Kartagener syndrome). It is caused by motility defects in the respiratory cilia that are responsible for airway clearance, the flagella that propel sperm cells and the nodal monocilia that determine left-right asymmetry1. Recessive mutations that cause PCD have been identified in genes encoding components of the outer dynein arms, radial spokes and cytoplasmic pre-assembly factors of axonemal dyneins, but these mutations account for only about 50% of cases of PCD. We exploited the unique properties of dog populations to positionally clone a new PCD gene, CCDC39. We found that loss-of-function mutations in the human ortholog underlie a substantial fraction of PCD cases with axonemal disorganization and abnormal ciliary beating. Functional analyses indicated that CCDC39 localizes to ciliary axonemes and is essential for assembly of inner dynein arms and the dynein regulatory complex.
PMCID: PMC3509786  PMID: 21131972
18.  Differentiating Central Centrifugal Cicatricial Alopecia and Androgenetic Alopecia in African American Men 
Central centrifugal cicatricial alopecia is a scarring alopecia that is predominantly seen in African American women, but occurs less frequently in men. The authors present three cases of African American men with biopsy-proven central centrifugal cicatricial alopecia and detail the clinical presentation, histological findings, and treatment regimens. Central centrifugal cicatricial alopecia should be considered in the differential diagnosis when evaluating male patients with vertex hair loss accompanied by scalp symptoms. Physicians should maintain a high index of suspicion in African American men with the appropriate clinical picture and confirm the diagnosis by scalp biopsy. Prompt and appropriate treatment can help halt or slow disease progression.
PMCID: PMC3390231  PMID: 22768355
19.  Validity of Self-Reported Solar UVR Exposure Compared to Objectively Measured UVR Exposure 
Reliance on verbal self-report of solar exposure in skin cancer prevention and epidemiologic studies may be problematic if self-report data are not valid due to systematic errors in recall, social desirability bias, or other reasons.
This study examines the validity of self-reports of exposure to ultraviolet radiation (UVR) compared to objectively measured exposure among children and adults in outdoor recreation settings in four regions of the United States. Objective UVR exposures of 515 participants were measured using polysulfone film badge UVR dosimeters on two days. The same subjects provided self-reported UVR exposure data on surveys and 4-day sun exposure diaries, for comparison to their objectively measured exposure.
Dosimeter data showed that lifeguards had the greatest UVR exposure (24.5% of weekday ambient UVR), children the next highest exposures (10.3% ambient weekday UVR) and parents had the lowest (6.6% ambient weekday UVR). Similar patterns were observed in self-report data. Correlations between diary reports and dosimeter findings were fair to good and were highest for lifeguards (r = 0.38 – 0.57), followed by parents (r = 0.28 – 0.29) and children (r = 0.18 – 0.34). Correlations between survey and diary measures were moderate to good for lifeguards (r = 0.20 – 0.54) and children (r = 0.35 – 0.53).
This is the largest study of its kind to date, and supports the utility of self-report measures of solar UVR exposure.
Overall, self-reports of sun exposure produce valid measures of UVR exposure among parents, children, and lifeguards who work outdoors.
PMCID: PMC3005549  PMID: 20940277
skin cancer; sun exposure; UVR; dosimeters; validation; biomarkers
20.  TTC21B contributes both causal and modifying alleles across the ciliopathy spectrum 
Nature genetics  2011;43(3):189-196.
Ciliary dysfunction leads to a broad range of overlapping phenotypes, termed collectively as ciliopathies. This grouping is underscored by genetic overlap, where causal genes can also contribute modifying alleles to clinically distinct disorders. Here we show that mutations in TTC21B/IFT139, encoding a retrograde intraflagellar transport (IFT) protein, cause both isolated nephronophthisis (NPHP) and syndromic Jeune Asphyxiating Thoracic Dystrophy (JATD). Moreover, although systematic medical resequencing of a large, clinically diverse ciliopathy cohort and matched controls showed a similar frequency of rare changes, in vivo and in vitro evaluations unmasked a significant enrichment of pathogenic alleles in cases, suggesting that TTC21B contributes pathogenic alleles to ∼5% of ciliopathy patients. Our data illustrate how genetic lesions can be both causally associated with diverse ciliopathies, as well as interact in trans with other disease-causing genes, and highlight how saturated resequencing followed by functional analysis of all variants informs the genetic architecture of disorders.
PMCID: PMC3071301  PMID: 21258341
21.  Identification of 11 Novel Mutations in 8 BBS Genes by High-Resolution Homozygosity Mapping 
Journal of medical genetics  2009;47(4):262-267.
Bardet-Biedl syndrome (BBS) is primarily an autosomal recessive disorder characterized by the five cardinal features retinitis pigmentosa, postaxial polydactyly, mental retardation, obesity and hypogenitalism. In addition, renal cysts and other anomalies of the kidney and urinary tract can be present. To date, mutations in 12 BBS genes as well as in MKS1 and CEP290 have been identified as causing BBS. The vast genetic heterogeneity of BBS renders molecular genetic diagnosis difficult in terms of both the time and cost required to screen all 204 coding exons. Here, we report the use of genome-wide homozygosity mapping as a tool to identify homozygous segments at known BBS loci in BBS individuals from inbred and outbred background. In a worldwide cohort of 45 families, we identified, via direct exon sequencing, causative homozygous mutations in 20 families. Eleven of these mutations were novel, thereby increasing the number of known BBS mutations by 5% (11/218). Thus, in the presence of extreme genetic locus heterogeneity, homozygosity mapping provides a valuable approach to the molecular genetic diagnosis of BBS and will facilitate the discovery of novel pathogenic mutations.
PMCID: PMC3017466  PMID: 19797195
Molecular Genetics
22.  The Vertebrate Primary Cilium in Development, Homeostasis, and Disease 
Cell  2009;137(1):32-45.
Cilia are complex structures that have garnered interest because of their roles in vertebrate development and their involvement in human genetic disorders. In contrast to multicellular invertebrates in which cilia are restricted to specific cell types, these organelles are found almost ubiquitously in vertebrate cells, where they serve a diverse set of signaling functions. Here, we highlight properties of vertebrate cilia, with particular emphasis on their relationship with other subcellular structures, and explore the physiological consequences of ciliary dysfunction.
PMCID: PMC3016012  PMID: 19345185
23.  Mutations in TMEM216 perturb ciliogenesis and cause Joubert, Meckel and related syndromes 
Nature genetics  2010;42(7):619-625.
Joubert syndrome (JBTS), related disorders (JSRD) and Meckel syndrome (MKS) are ciliopathies. We now report that MKS2 and JBTS2 loci are allelic and due to mutations in TMEM216, encoding an uncharacterized tetraspan transmembrane protein. JBTS2 patients displayed frequent nephronophthisis and polydactytly, and two cases conformed to the Oro-Facio-Digital type VI phenotype, whereas skeletal dysplasia was common in MKS fetuses. A single p.R73L mutation was identified in all patients of Ashkenazi Jewish descent (n=10). TMEM216 localized to the base of primary cilia, and loss of TMEM216 in patient fibroblasts or following siRNA knockdown caused defective ciliogenesis and centrosomal docking, with concomitant hyperactivation of RhoA and Dishevelled. TMEM216 complexed with Meckelin, encoded by a gene also mutated in JSRD and MKS. Abrogation of tmem216 expression in zebrafish led to gastrulation defects that overlap with other ciliary morphants. The data implicate a new family of proteins in the ciliopathies, and further support allelism between ciliopathy disorders.
PMCID: PMC2894012  PMID: 20512146
24.  Training for and Dissemination of the Nutrition Environment Measures Surveys (NEMS) 
Preventing Chronic Disease  2010;7(6):A126.
Researchers believe that nutrition environments contribute to obesity and may explain some health disparities. The Nutrition Environment Measures Surveys (NEMS) are valid and reliable observational measures of the nutrition environment. This article describes the dissemination of the measures, including the development, implementation, and evaluation of training workshops, and a follow-up survey of training participants.
To disseminate the NEMS measures, we developed a 2-day intensive, participatory workshop. We used an immediate postcourse evaluation and a structured telephone follow-up interview to evaluate the workshops and the dissemination strategy. Topics included use of the NEMS measures, reactions to the workshops, and participants' training others on the measures.
During the study period, 173 people participated in 14 workshops. Participants indicated a high level of satisfaction with the training workshops. Almost two-thirds of respondents reported using the measures to train an additional 292 people and to rate more than 3,000 food outlets. The measures have been used in diverse locations across the United States for various purposes. Respondents have reported NEMS results in peer-reviewed journals, master's theses, newspaper articles, and presentations.
The NEMS measures are the only nutrition environment measures that have been packaged for distribution and widely disseminated. The measures fill a need in the worlds of research and community action, and dissemination was successful in accelerating diffusion and promoting adoption of the measures. The use of an ongoing, continual process to improve workshops and measures contributes to the usefulness of the surveys and accelerates their adoption and continued use.
PMCID: PMC2995598  PMID: 20950533
25.  Postinflammatory Hyperpigmentation 
Postinflammatory hyperpigmentation is a common sequelae of inflammatory dermatoses that tends to affect darker skinned patients with greater frequency and severity. Epidemiological studies show that dyschromias, including postinflammatory hyperpigmentation, are among the most common reasons darker racial/ethnic groups seek the care of a dermatologist. The treatment of postinflammatory hyperpigmentation should be started early to help hasten its resolution and begins with management of the initial inflammatory condition. First-line therapy typically consists of topical depigmenting agents in addition to photoprotection including a sunscreen. Topical tyrosinase inhibitors, such as hydroquinone, azelaic acid, kojic acid, arbutin, and certain licorice extracts, can effectively lighten areas of hypermelanosis. Other depigmenting agents include retinoids, mequinol, ascorbic acid, niacinamide, N-acetyl glucosamine, and soy with a number of emerging therapies on the horizon. Topical therapy is typically effective for epidermal postinflammatory hyperpigmentation; however, certain procedures, such as chemical peeling and laser therapy, may help treat recalcitrant hyperpigmentation. It is also important to use caution with all of the above treatments to prevent irritation and worsening of postinflammatory hyperpigmentation.
PMCID: PMC2921758  PMID: 20725554

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