RESUMO
Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is the most common craniofacial birth defect in humans and is notable for its apparent sexual dimorphism where approximately twice as many males are affected as females. The sources of this disparity are largely unknown, but interactions between genetic and sex effects are likely contributors. We examined gene-by-sex (G × S) interactions in a worldwide sample of 2,142 NSCL/P cases and 1,700 controls recruited from 13 countries. First, we performed genome-wide joint tests of the genetic (G) and G × S effects genome-wide using logistic regression assuming an additive genetic model and adjusting for 18 principal components of ancestry. We further interrogated loci with suggestive results from the joint test ( p < 1.00 × 10 -5 ) by examining the G × S effects from the same model. Out of the 133 loci with suggestive results ( p < 1.00 × 10 -5 ) for the joint test, we observed one genome-wide significant G × S effect in the 10q21 locus (rs72804706; p = 6.69 × 10 -9 ; OR = 2.62 CI [1.89, 3.62]) and 16 suggestive G × S effects. At the intergenic 10q21 locus, the risk of NSCL/P is estimated to increase with additional copies of the minor allele for females, but the opposite effect for males. Our observation that the impact of genetic variants on NSCL/P risk differs for males and females may further our understanding of the genetic architecture of NSCL/P and the sex differences underlying clefts and other birth defects.
Assuntos
Alelos , Encéfalo/anormalidades , Fenda Labial/genética , Fissura Palatina/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Caracteres Sexuais , Estudos de Casos e Controles , Epistasia Genética , Feminino , Frequência do Gene/genética , Loci Gênicos , Humanos , Masculino , Modelos Genéticos , Polimorfismo de Nucleotídeo Único , Fatores de RiscoRESUMO
Cleft palate (CP) is a common birth defect occurring in 1 in 2,500 live births. Approximately half of infants with CP have a syndromic form, exhibiting other physical and cognitive disabilities. The other half have nonsyndromic CP, and to date, few genes associated with risk for nonsyndromic CP have been characterized. To identify such risk factors, we performed a genome-wide association study of this disorder. We discovered a genome-wide significant association with a missense variant in GRHL3 (p.Thr454Met [c.1361C>T]; rs41268753; p = 4.08 × 10(-9)) and replicated the result in an independent sample of case and control subjects. In both the discovery and replication samples, rs41268753 conferred increased risk for CP (OR = 8.3, 95% CI 4.1-16.8; OR = 2.16, 95% CI 1.43-3.27, respectively). In luciferase transactivation assays, p.Thr454Met had about one-third of the activity of wild-type GRHL3, and in zebrafish embryos, perturbed periderm development. We conclude that this mutation is an etiologic variant for nonsyndromic CP and is one of few functional variants identified to date for nonsyndromic orofacial clefting. This finding advances our understanding of the genetic basis of craniofacial development and might ultimately lead to improvements in recurrence risk prediction, treatment, and prognosis.
Assuntos
Fissura Palatina/genética , Proteínas de Ligação a DNA/genética , Polimorfismo de Nucleotídeo Único , Fatores de Transcrição/genética , Animais , Estudos de Casos e Controles , Fissura Palatina/diagnóstico , Modelos Animais de Doenças , Etnicidade/genética , Loci Gênicos , Estudo de Associação Genômica Ampla , Técnicas de Genotipagem , Humanos , Mutação de Sentido Incorreto , Fatores de Risco , Peixe-Zebra/embriologia , Peixe-Zebra/genéticaRESUMO
Genome-wide scans have shown that common risk alleles for orofacial clefts (OFC) tend to be located in noncoding regulatory elements and cumulatively explain only part of the heritability of OFCs. Low-frequency variants may account for some of the "missing" heritability. Therefore, we scanned low-frequency variants located within putative craniofacial enhancers to identify novel OFC risk variants and implicate new regulatory elements in OFC pathogenesis. Analyses were performed in a multiethnic sample of 1,995 cases of cleft lip with or without cleft palate (CL/P), 221 cases with cleft palate (CP) only, and 1,576 unaffected controls. One hundred and nineteen putative craniofacial enhancers identified from ChIP-Seq studies in craniofacial tissues or cell lines contained multiple low-frequency (0.01-1%) variants, which we genotyped in participants using a custom Illumina panel. Two complementary statistical approaches, sequence kernel association test and combined multivariate and collapsing, were used to test association of the aggregated low-frequency variants across each enhancer region with CL/P and CP. We discovered a significant association between CP and a branchial arch enhancer near FOXP1 (mm60; p-value = .0002). Additionally, we observed a suggestive association between CL/P and a forebrain enhancer near FOXE1 (hs1717; p-value = .001). These findings suggest that low-frequency variants in craniofacial enhancer regions contribute to the complex etiology of nonsyndromic OFCs.
Assuntos
Encéfalo/anormalidades , Fenda Labial/diagnóstico , Fenda Labial/genética , Fissura Palatina/diagnóstico , Fissura Palatina/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Variação Genética , Sequências Reguladoras de Ácido Nucleico , Alelos , Elementos Facilitadores Genéticos , Estudos de Associação Genética/métodos , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Orofacial clefts (OFCs) are common, complex birth defects with extremely heterogeneous phenotypic presentations. Two common subtypes-cleft lip alone (CL) and CL plus cleft palate (CLP)-are typically grouped into a single phenotype for genetic analysis (i.e., CL with or without cleft palate, CL/P). However, mounting evidence suggests there may be unique underlying pathophysiology and/or genetic modifiers influencing expression of these two phenotypes. To this end, we performed a genome-wide scan for genetic modifiers by directly comparing 450 CL cases with 1,692 CLP cases from 18 recruitment sites across 13 countries from North America, Central or South America, Asia, Europe, and Africa. We identified a region on 16q21 that is strongly associated with different cleft type (P = 5.611 × 10-8 ). We also identified significant evidence of gene-gene interactions between this modifier locus and two recognized CL/P risk loci: 8q21 and 9q22 (FOXE1) (P = 0.012 and 0.023, respectively). Single nucleotide polymorphism (SNPs) in the 16q21 modifier locus demonstrated significant association with CL over CLP. The marker alleles on 16q21 that increased risk for CL were found at highest frequencies among individuals with a family history of CL (P = 0.003). Our results demonstrate the existence of modifiers for which type of OFC develops and suggest plausible elements responsible for phenotypic heterogeneity, further elucidating the complex genetic architecture of OFCs.
Assuntos
Encéfalo/anormalidades , Cromossomos Humanos Par 16 , Fenda Labial/genética , Fissura Palatina/genética , Alelos , Encéfalo/patologia , Fenda Labial/patologia , Fissura Palatina/patologia , Feminino , Fatores de Transcrição Forkhead/genética , Loci Gênicos , Estudo de Associação Genômica Ampla , Humanos , Masculino , Fenótipo , Polimorfismo de Nucleotídeo Único , Grupos Raciais/genética , Fatores de RiscoRESUMO
Orofacial clefts (OFCs), which include non-syndromic cleft lip with or without cleft palate (CL/P), are among the most common birth defects in humans, affecting approximately 1 in 700 newborns. CL/P is phenotypically heterogeneous and has a complex etiology caused by genetic and environmental factors. Previous genome-wide association studies (GWASs) have identified at least 15 risk loci for CL/P. As these loci do not account for all of the genetic variance of CL/P, we hypothesized the existence of additional risk loci. We conducted a multiethnic GWAS in 6480 participants (823 unrelated cases, 1700 unrelated controls and 1319 case-parent trios) with European, Asian, African and Central and South American ancestry. Our GWAS revealed novel associations on 2p24 near FAM49A, a gene of unknown function (P = 4.22 × 10-8), and 19q13 near RHPN2, a gene involved in organizing the actin cytoskeleton (P = 4.17 × 10-8). Other regions reaching genome-wide significance were 1p36 (PAX7), 1p22 (ARHGAP29), 1q32 (IRF6), 8q24 and 17p13 (NTN1), all reported in previous GWASs. Stratification by ancestry group revealed a novel association with a region on 17q23 (P = 2.92 × 10-8) among individuals with European ancestry. This region included several promising candidates including TANC2, an oncogene required for development, and DCAF7, a scaffolding protein required for craniofacial development. In the Central and South American ancestry group, significant associations with loci previously identified in Asian or European ancestry groups reflected their admixed ancestry. In summary, we have identified novel CL/P risk loci and suggest new genes involved in craniofacial development, confirming the highly heterogeneous etiology of OFCs.
Assuntos
Fenda Labial/genética , Fissura Palatina/genética , Povo Asiático/genética , População Negra/genética , Cromossomos Humanos Par 17/genética , Cromossomos Humanos Par 19/genética , Cromossomos Humanos Par 2/genética , Etnicidade , Feminino , Loci Gênicos , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Masculino , Polimorfismo de Nucleotídeo Único/genética , Fatores de Risco , População Branca/genéticaRESUMO
Double-stranded RNA (dsRNA) can induce antiviral enzyme 2',5'-oligoadenylate synthetase (2'5'AS) expression and activate latent 2'5'AS. Our previous data have shown pancreatic ß cells are sensitive to dsRNA-induced 2'5'AS expression, and constitutive high basal 2'5'AS expression is associated with susceptibility to developing type 1 diabetes (T1D), a disease due to pancreatic ß cell loss. Here we report that in vitro transcribed human insulin mRNA induces the activation of human OAS gene promoter sequences, and specifically and dose-dependently induces 2'5'AS expression in murine pancreatic ßTC3 cells. Over-expression of dsRNA receptor retinoic acid-inducible gene-1 enhances insulin mRNA-induced 2'5'AS expression. In vitro transcribed insulin and other mRNAs, as well as total cellular RNAs, activate latent 2'5'AS in vitro with activation ability likely associated with the sequence and length of individual mRNAs or the sample source of total cellular RNA. Insulin mRNA does not show any specificity to activate 2'5'AS, but total cellular RNA from ßTC3 cells has high activation ability. Constitutive 2'5'AS expression in ßTC3 cells leads to cell proliferation inhibition and apoptosis. Our study suggests the possibility of cellular RNA-regulated 2'5'AS expression and activation, and the potential risk of high insulin gene transcription in pancreatic ß cells, and may help explain genetic predisposition to T1D associated with INS VNTR class I alleles.
Assuntos
2',5'-Oligoadenilato Sintetase/biossíntese , Diabetes Mellitus Tipo 1/genética , Células Secretoras de Insulina/metabolismo , Insulina/genética , RNA de Cadeia Dupla/genética , 2',5'-Oligoadenilato Sintetase/metabolismo , Animais , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Proteína DEAD-box 58 , RNA Helicases DEAD-box/biossíntese , Predisposição Genética para Doença , Células HEK293 , Células HeLa , Humanos , Células Secretoras de Insulina/enzimologia , Glicoproteínas de Membrana/biossíntese , Camundongos , Camundongos Endogâmicos BALB C , Repetições Minissatélites , Regiões Promotoras Genéticas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptor 7 Toll-Like/biossínteseRESUMO
OBJECTIVES: Non-syndromic orofacial clefts, i.e. cleft lip (CL) and cleft palate (CP), are among the most common birth defects. The goal of this study was to identify genomic regions and genes for CL with or without CP (CL/P). METHODS: We performed linkage analyses of a 10 cM genome scan in 820 multiplex CL/P families (6,565 individuals). Significant linkage results were followed by association analyses of 1,476 SNPs in candidate genes and regions, utilizing a weighted false discovery rate (wFDR) approach to control for multiple testing and incorporate the genome scan results. RESULTS: Significant (multipoint HLOD >or=3.2) or genome-wide-significant (HLOD >or=4.02) linkage results were found for regions 1q32, 2p13, 3q27-28, 9q21, 12p11, 14q21-24 and 16q24. SNPs in IRF6 (1q32) and in or near FOXE1 (9q21) reached formal genome-wide wFDR-adjusted significance. Further, results were phenotype dependent in that the IRF6 region results were most significant for families in which affected individuals have CL alone, and the FOXE1 region results were most significant in families in which some or all of the affected individuals have CL with CP. CONCLUSIONS: These results highlight the importance of careful phenotypic delineation in large samples of families for genetic analyses of complex, heterogeneous traits such as CL/P.
Assuntos
Fenda Labial/genética , Fissura Palatina/genética , Ligação Genética , Genoma Humano , Estudo de Associação Genômica Ampla , Mapeamento Cromossômico , Cromossomos Humanos/genética , Predisposição Genética para Doença , Humanos , Fenótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Cleft lip or palate (or the two in combination) is a common birth defect that results from a mixture of genetic and environmental factors. We searched for a specific genetic factor contributing to this complex trait by examining large numbers of affected patients and families and evaluating a specific candidate gene. METHODS: We identified the gene that encodes interferon regulatory factor 6 (IRF6) as a candidate gene on the basis of its involvement in an autosomal dominant form of cleft lip and palate, Van der Woude's syndrome. A single-nucleotide polymorphism in this gene results in either a valine or an isoleucine at amino acid position 274 (V274I). We carried out transmission-disequilibrium testing for V274I in 8003 individual subjects in 1968 families derived from 10 populations with ancestry in Asia, Europe, and South America, haplotype and linkage analyses, and case-control analyses, and determined the risk of cleft lip or palate that is associated with genetic variation in IRF6. RESULTS: Strong evidence of overtransmission of the valine (V) allele was found in the entire population data set (P<10(-9)); moreover, the results for some individual populations from South America and Asia were highly significant. Variation at IRF6 was responsible for 12 percent of the genetic contribution to cleft lip or palate and tripled the risk of recurrence in families that had already had one affected child. CONCLUSIONS: DNA-sequence variants associated with IRF6 are major contributors to cleft lip, with or without cleft palate. The contribution of variants in single genes to cleft lip or palate is an important consideration in genetic counseling.
Assuntos
Fenda Labial/genética , Fissura Palatina/genética , Proteínas de Ligação a DNA/genética , Fatores de Transcrição/genética , Genótipo , Haplótipos , Humanos , Fatores Reguladores de Interferon , Desequilíbrio de Ligação , Linhagem , Polimorfismo Genético , Grupos Raciais , Fatores de Risco , ValinaRESUMO
Nonsyndromic clefts of the lip and/or palate are common birth defects with a strong genetic component. Based on unequal gender ratios for clefting phenotypes, evidence for linkage to the X chromosome and the occurrence of several X-linked clefting syndromes, we investigated the role of skewed X chromosome inactivation (XCI) in orofacial clefts. Our samples consisted of female monozygotic (MZ) twins (n = 8) and sister pairs (n = 152) discordant for nonsyndromic clefting. We measured the XCI pattern in peripheral blood lymphocyte DNA using a methylation based androgen receptor gene assay. Skewing of XCI was defined as the deviation in inactivation pattern from a 50:50 ratio. Our analysis revealed no significant difference in the degree of skewing between twin pairs (P = 0.3). However, borderline significant differences were observed in the sister pairs (P = 0.02), with the cleft lip with cleft palate group showing the most significant result (P = 0.01). We did not find evidence for involvement of skewed XCI in the discordance for clefting in our sample of female MZ twins. However, results from the paired sister study suggest the potential contribution of skewed XCI to orofacial clefting, particularly cleft lip and palate.
Assuntos
Cromossomos Humanos X , Fenda Labial/genética , Fissura Palatina/genética , Inativação do Cromossomo X , Doenças em Gêmeos , Feminino , Humanos , Modelos Genéticos , Modelos Estatísticos , Fenótipo , Análise de Sequência de DNA , Gêmeos MonozigóticosRESUMO
Both genetic and nongenetic factors contribute to the development of type 1 diabetes. Many investigations, including prospective studies of high-risk children, have implicated virus infections as predisposing environmental agents. We previously reported that basal activity of the key antiviral enzyme 2'5'-oligoadenylate synthetase (2'5'AS) was significantly elevated in type 1 diabetic patients compared with healthy control subjects. Recently, we showed that an A/G splice site single nucleotide polymorphism (SNP) in the OAS1 gene encoding 2'5'AS is strongly associated with basal 2'5'AS activity. Basal enzyme activity was highest in individuals with GG genotype and lowest in those with AA genotype. In the present study, we genotyped 835 type 1 diabetic and 401 healthy siblings at the OAS1 splice site polymorphism and (for comparison) at an A/C SNP of the insulin (IDDM2) locus. Results showed that OAS1 GG and GA were significantly increased in diabetic compared with healthy siblings (P = 0.0023). The strength of association was similar to that at IDDM2, where, as expected, the C/C (variable number tandem repeat class I homozygote) genotype was increased in affected compared with healthy siblings (P = 0.0025). The results suggest that host genetic response to virus infection could influence susceptibility to type 1 diabetes.
Assuntos
2',5'-Oligoadenilato Sintetase/genética , Processamento Alternativo , Diabetes Mellitus Tipo 1/genética , Predisposição Genética para Doença/genética , Polimorfismo de Nucleotídeo Único , Genótipo , Humanos , Valores de Referência , IrmãosRESUMO
A dozen genes/regions have been confirmed as genetic risk factors for oral clefts in human association and linkage studies, and animal models argue even more genes may be involved. Genomic sequencing studies should identify specific causal variants and may reveal additional genes as influencing risk to oral clefts, which have a complex and heterogeneous etiology. We conducted a whole exome sequencing (WES) study to search for potentially causal variants using affected relatives drawn from multiplex cleft families. Two or three affected second, third, and higher degree relatives from 55 multiplex families were sequenced. We examined rare single nucleotide variants (SNVs) shared by affected relatives in 348 recognized candidate genes. Exact probabilities that affected relatives would share these rare variants were calculated, given pedigree structures, and corrected for the number of variants tested. Five novel and potentially damaging SNVs shared by affected distant relatives were found and confirmed by Sanger sequencing. One damaging SNV in CDH1, shared by three affected second cousins from a single family, attained statistical significance (P = 0.02 after correcting for multiple tests). Family-based designs such as the one used in this WES study offer important advantages for identifying genes likely to be causing complex and heterogeneous disorders.
Assuntos
Fissura Palatina/genética , Exoma/genética , Estudos de Associação Genética , Mutação/genética , Análise de Sequência de DNA/métodos , Antígenos CD , Caderinas/genética , Etnicidade/genética , Família , Feminino , Humanos , Masculino , Linhagem , Reprodutibilidade dos TestesRESUMO
Case-parent trios were used in a genome-wide association study of cleft lip with and without cleft palate. SNPs near two genes not previously associated with cleft lip with and without cleft palate (MAFB, most significant SNP rs13041247, with odds ratio (OR) per minor allele = 0.704, 95% CI 0.635-0.778, P = 1.44 x 10(-11); and ABCA4, most significant SNP rs560426, with OR = 1.432, 95% CI 1.292-1.587, P = 5.01 x 10(-12)) and two previously identified regions (at chromosome 8q24 and IRF6) attained genome-wide significance. Stratifying trios into European and Asian ancestry groups revealed differences in statistical significance, although estimated effect sizes remained similar. Replication studies from several populations showed confirming evidence, with families of European ancestry giving stronger evidence for markers in 8q24, whereas Asian families showed stronger evidence for association with MAFB and ABCA4. Expression studies support a role for MAFB in palatal development.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Fenda Labial/genética , Fissura Palatina/genética , Predisposição Genética para Doença , Fator de Transcrição MafB/genética , Polimorfismo de Nucleotídeo Único , Animais , Povo Asiático/genética , Feminino , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Camundongos , População Branca/genéticaRESUMO
Human linkage and association studies suggest a gene(s) for nonsyndromic cleft lip with or without cleft palate (CL/P) on chromosome 4q31-q32 at or near the platelet-derived growth factor-C (PDGF-C) locus. The mouse Pdgfc(-/-) knockout shows that PDGF-C is essential for palatogenesis. To evaluate the role of PDGF-C in human clefting, we performed sequence analysis and SNP genotyping using 1048 multiplex CL/P families and 1000 case-control samples from multiple geographic origins. No coding region mutations were identified, but a novel -986 C>T SNP (rs28999109) was significantly associated with CL/P (P=0.01) in cases from Chinese families yielding evidence of linkage to 4q31-q32. Significant or near-significant association was also seen for this and several other PDGF-C SNPs in families from the United States, Spain, India, Turkey, China, and Colombia, whereas no association was seen in families from the Philippines, and Guatemala, and case-controls from Brazil. The -986T allele abolished six overlapping potential transcription regulatory motifs. Transfection assays of PDGF-C promoter reporter constructs show that the -986T allele is associated with a significant decrease (up to 80%) of PDGF-C gene promoter activity. This functional polymorphism acting on a susceptible genetic background may represent a component of human CL/P etiology.
Assuntos
Fenda Labial/genética , Fissura Palatina/genética , Linfocinas/genética , Fator de Crescimento Derivado de Plaquetas/genética , Polimorfismo de Nucleotídeo Único/genética , Regiões Promotoras Genéticas/genética , Transcrição Gênica/genética , Alelos , Estudos de Casos e Controles , Predisposição Genética para Doença , HumanosRESUMO
It is likely that human genetic differences mediate susceptibility to viral infection and virus-triggered disorders. OAS genes encoding the antiviral enzyme 2',5'-oligoadenylate synthetase (2'5'AS) are critical components of the innate immune response to viruses. This enzyme uses adenosine triphosphate in 2'-specific nucleotidyl transfer reactions to synthesize 2',5'-oligoadenylates, which activate latent ribonuclease, resulting in degradation of viral RNA and inhibition of virus replication. We showed elsewhere that constitutive (basal) activity of 2'5'AS is correlated with virus-stimulated activity. In the present study, we asked whether constitutive activity is genetically determined and, if so, by which variants. Analysis of 83 families containing two parents and two children demonstrated significant correlations between basal activity in parent-child pairs (P<.0001) and sibling pairs (P=.0044), but not spousal pairs, suggesting strong genetic control of basal activity. We next analyzed association between basal activity and 15 markers across the OAS gene cluster. Significant association was detected at multiple markers, the strongest being at an A/G single-nucleotide polymorphism at the exon 7 splice-acceptor site (AG or AA) of the OAS1 gene. At this unusual polymorphism, allele G had a higher gene frequency in persons with high enzyme activity than in those with low enzyme activity (0.44 vs. 0.20; P=3 x 10(-11)). Enzyme activity varied in a dose-dependent manner across the GG, GA, and AA genotypes (tested by analysis of variance; P=1 x 10(-14)). Allele G generates the previously described p46 enzyme isoform, whereas allele A ablates the splice site and generates a dual-function antiviral/proapoptotic p48 isoform and a novel p52 isoform. This genetic polymorphism makes OAS1 an excellent candidate for a human gene that influences host susceptibility to viral infection.
Assuntos
2',5'-Oligoadenilato Sintetase/genética , Polimorfismo de Nucleotídeo Único , Sítios de Splice de RNA/genética , Sequência de Aminoácidos , Sequência de Bases , Feminino , Humanos , Masculino , Dados de Sequência MolecularRESUMO
Dyslexia is a common and genetically complex trait that manifests primarily as a reading disability independent of general intelligence and educational opportunity. Strong evidence for a dyslexia susceptibility locus on chromosome 1p34-p36 (near marker D1S199) was recently reported, and an earlier study found suggestive evidence for linkage to the same region. We tested for the presence of a dyslexia gene in this region in a sample of 100 Canadian families using both qualitative and quantitative definitions of the phenotype. Using a qualitative definition of dyslexia (affected, unaffected, or uncertain), the largest multipoint Genehunter Maximum LOD-Score (MLS) in 100 core nuclear families was 3.65 at D1S507, distal to D1S199. Quantitative trait locus (QTL) linkage analysis was performed for four measures of dyslexia (phonological awareness, phonological coding, spelling, and rapid automatized naming speed) employing the variance components approach implemented in Genehunter. Using a model with QTL additive and dominance variance and polygenic additive variance, the multipoint LOD scores maximized proximal to D1S199 (between D1S552 and D1S1622), with peaks of 4.01 for spelling and 1.65 for phonological coding (corresponding LOD scores under 1 degree of freedom were 3.30 and 1.13, respectively). In conclusion, our study confirms and strengthens recent findings of a dyslexia susceptibility gene on chromosome 1p34-p36 (now designated DYX8).
Assuntos
Cromossomos Humanos Par 1/genética , Dislexia/genética , Predisposição Genética para Doença/genética , Canadá , Criança , Mapeamento Cromossômico , Dislexia/patologia , Saúde da Família , Genótipo , Humanos , Escore Lod , Repetições de Microssatélites , FenótipoRESUMO
OBJECTIVE: Involvement of loci on chromosome 17, including retinoic acid receptor alpha (RARA) in nonsyndromic oral clefts has been reported in Caucasian populations, although never investigated in Asian populations. The purpose of the present study was to investigate several loci on chromosome 17, including RARA, in Chinese families. PARTICIPANTS: Thirty-six multiplex families (310 individuals), ascertained through nonsyndromic cleft lip with or without cleft palate surgical probands from hospitals in Shanghai, China, participated in the present study. There were 23 families whose probands had cleft lip and cleft palate (CLP) and 13 with cleft lip alone (CL). RESULTS: Seventeen markers, spanning chromosome 17 and about 10 cM apart were assessed. Logarithm of odds ratio (LOD) scores (two point and multipoint), model-free linkage analyses, and allelic association tests (transmission/disequilibrium, Fisher's exact tests, and chi-square) were performed on the total family sample, families with CLP probands (CLP subgroup), and families with CL probands (CL subgroup). LOD scores from the two-point analyses were inconclusive. Multipoint analyses rejected linkage except for a few regions in the CL subgroup. However, positive results were found using the model-free linkage and association methods (p < .05). The markers with positive results varied across the CL and CLP subgroups. However, the RARA region and loci nearby yielded consistently positive results. CONCLUSION: Genetic variation within the RARA locus or nearby appears to be involved in the pathogenesis of nonsyndromic oral clefts in this population. Furthermore, based on the differing pattern of results in the CL versus CLP subgroups, it appears that the formation of CL and CLP is because of either differing alleles at the same genetic locus or different but related (and/or linked) genes that modify the severity and expression of oral clefting.
Assuntos
Povo Asiático/genética , Mapeamento Cromossômico , Cromossomos Humanos Par 17/genética , Fenda Labial/genética , Fissura Palatina/genética , Alelos , Distribuição de Qui-Quadrado , China , DNA/genética , Ligação Genética/genética , Marcadores Genéticos/genética , Variação Genética/genética , Humanos , Desequilíbrio de Ligação/genética , Escore Lod , Modelos Genéticos , Receptores do Ácido Retinoico/genética , Receptor alfa de Ácido Retinoico , Estatística como AssuntoRESUMO
Cleft lip with or without cleft palate (CL/P) is a common congenital anomaly, with birth prevalence ranging from 1/500 to 1/1,000. A number of genetic loci have shown positive linkage or association results in European Caucasian populations. The purpose of the current study was to assess whether any of those loci have positive results in Turkish Caucasian CL/P families, and to perform a 10 cM genome scan to identify other regions potentially containing cleft susceptibility loci. Eighteen affected individuals with consanguineous parents were identified as part of our on-going studies of orofacial clefts in Ankara, Turkey. Genotyped were 383 genome-scan markers, and 70 additional markers, including markers in six candidate loci or regions on chromosomes 2, 4, 6, 14, 17, and 19 (TGFA, D4S175, F13A1, TGFB3, D17S250, and APOC2) that have been implicated in other studies of families with orofacial clefting. LOD scores (two point and multiple point) and family-based association statistics (TDT) were calculated between each of the markers and CL/P. For the LOD score calculations, an autosomal recessive model was assumed for the inheritance of CL/P. Of the six candidate markers, significant TDT results were obtained with TGFA (P = 0.05). The most statistically significant multipoint results from the linkage genome scan were between putative genes controlling risk of CL/P and regions on chromosomes 4, 10, 12, and 15 (maximum multipoint HLOD's of 1.25, 1.30, 2.73, and 1.28 respectively). These results demonstrate the power of small numbers of families with inbred probands to detect linkage and association.
Assuntos
Fenda Labial/genética , Fissura Palatina/genética , Consanguinidade , Família , Genoma Humano , Cromossomos Humanos Par 10 , Cromossomos Humanos Par 12 , Cromossomos Humanos Par 15 , Cromossomos Humanos Par 4 , Feminino , Ligação Genética , Marcadores Genéticos , Humanos , Desequilíbrio de Ligação , Escore Lod , Masculino , Linhagem , TurquiaRESUMO
Dyslexia is a disability in acquiring reading and spelling skills that is independent of general intelligence and educational opportunity, and is highly heritable. It is known that dyslexia often co-occurs with attention deficit hyperactivity disorder (ADHD), and the 7-repeat allele of the 48-bp tandem repeat in exon 3 of the dopamine D4 receptor (DRD4) has been implicated in ADHD. We, therefore, investigated DRD4 as a candidate gene for dyslexia by testing for linkage and association with 14 markers at and around the DRD4 locus on chromosome 11p15.5. Using 100 families having at least two siblings affected with dyslexia, model-free linkage analysis revealed evidence for linkage to the DRD4-exon 3 repeat (two-point MFLOD = 2.27, P = 0.001) and to HRAS located just proximal to DRD4 (two-point MFLOD = 2.68, P = 0.0004). Evidence for linkage was maximal between DRD4 and HRAS (three-point MFLOD = 3.57, P = 0.00005). However, linkage disequilibrium analysis showed no significant evidence for association between dyslexia and DRD4 or HRAS. In particular, dyslexic subjects showed no significant increase of the DRD4 7-repeat allele associated with ADHD. It is possible that other DRD4 variants, not in strong linkage disequilibrium with the exon 3 repeat polymorphism, or alternatively, another gene very closely linked to DRD4, may influence susceptibility to dyslexia.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Cromossomos Humanos Par 11/genética , Dislexia/genética , Desequilíbrio de Ligação/genética , Receptores de Dopamina D2/genética , Alelos , Éxons/genética , Feminino , Humanos , Masculino , Repetições Minissatélites/genética , Receptores de Dopamina D4RESUMO
In order to identify genes or regions involved in nonsyndromic cleft lip with or without cleft palate (CL/P) in families from India, we analyzed 38 multiplex families (DNA from 272 individuals, 82 affected with CL/P, 190 unaffected) for 285 genome-wide markers (average spacing 12.6 cM), including markers in six candidate loci or regions on chromosomes 2, 4, 6, 14, 17, and 19 that have been implicated in other studies of CL/P. LOD scores (two-point and multipoint), and model-free association (TDT) and linkage (NPL) statistics, were calculated between each of the markers and a hypothetical CL/P susceptibility locus. The most statistically significant two-point linkage results were with markers on chromosome 7 (LOD = 1.89 with D7S435, 7p15, 47 cM), chromosome 5 (LOD = 1.76 with D5S407, 5q11, 65 cM), chromosome 15 (LOD = 1.55 with D15S652, 15q26, 90 cM), and chromosome 20 (LOD = 1.46 with STS155130, 20q13, 54 cM). The most significant multipoint linkage result was on chromosome 5q, again near D5S407 (HLOD = 1.40). Regions on chromosomes 1p, 1q, 7q, 12q, 16q, 18q, and Xp also had a LOD or HLOD > or = 1.0. Of seven candidate markers and regions with previous positive reports in the literature (TGFA, MSX1, D4S175, F13A1, TGFB3, D17S250, and APOC2), none had a significant linkage result, but one (the APOC2 region) had a significant association result and three others (TGFA, MSX1, F13A1) had suggestive results. The results are consistent with the involvement of multiple loci in CL/P expression in this West Bengal population, which concurs with results found in other CL/P study populations.
Assuntos
Fenda Labial/genética , Fissura Palatina/complicações , Predisposição Genética para Doença/genética , Genoma Humano , Alelos , Mapeamento Cromossômico , Fenda Labial/complicações , Fenda Labial/patologia , Saúde da Família , Feminino , Ligação Genética , Genótipo , Humanos , Índia , Escore Lod , Masculino , Repetições de Microssatélites , LinhagemRESUMO
Recombination between the X and Y chromosomes is limited to the pseudoautosomal region and is necessary for proper segregation of the sex chromosomes during spermatogenesis. Failure of the sex chromosomes to disjoin properly during meiosis can result in individuals with a 47,XXY constitution, and approximately one-half of these result from paternal nondisjunction at meiosis I. Analysis of individuals with paternally derived 47,XXY has shown that the majority are the result of meiosis in which the X and Y chromosomes have failed to recombine. Our studies of sperm have demonstrated that aneuploid 24,XY sperm have a decreased recombination frequency, compared with that of normal sperm. Some studies have indicated a relationship of increased paternal age with 47,XXY offspring and with the production of XY disomic sperm, whereas others have failed to find such relationships. To determine whether there is a relationship between paternal age and recombination in the pseudoautosomal region, single-sperm genotyping was performed to measure the frequency of recombination between a sex-specific locus, STS/STS pseudogene, and a pseudoautosomal locus, DXYS15, in younger men (age < or =30 years) compared with older men (age > or =50 years). A total of 2,329 sperm cells were typed by single-sperm PCR in 20 men who were heterozygous for the DXYS15 locus (1,014 sperm from 10 younger men and 1,315 sperm from 10 older men). The mean recombination frequency was 39.2% in the younger men and 37.8% in the older men. There was no heterogeneity in the frequency of recombination rates. There was no significant difference between the recombination frequencies among the younger men and those among the older men, when analyzed by the clustered binomial Z test (Z=.69, P=.49). This result suggests that paternal age has no effect on the recombination frequency in the pseudoautosomal region.