CBS c.844ins68 Polymorphism Frequencies in Control Populations: Implications on Nonsyndromic Cleft Lip With or Without Cleft Palate.

INTRODUCTION: Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common birth defect with substantial clinical and social impact. Folate deficiency is one of the factors that have been associated with increased risk for NSCLP. Polymorphisms in folate and homocysteine pathway genes may act as susceptibility factors. OBJECTIVE: The objective of this study was to evaluate prevalence estimates of cystathionine beta-synthase (CBS) insertion of 68-bp (c.844ins68) polymorphisms and their correlation with NSCLP. MATERIAL AND METHODS: A total of 236 unrelated individuals from seven Indian populations and an additional 355 cases with NSCLP and 357 controls without NSCLP were included in this study. We investigated the CBS c.844ins68 polymorphism in all samples. Genotyping was performed with polymerase chain reaction and electrophoresis. The data were statistically analyzed using the chi-square test. RESULTS: The CBS c.844ins68 allele is present in six of the seven populations analyzed, and allele frequencies range from 1.5% in Balija to 9.1% in Sugali populations. The CBS c.844ins68 polymorphism showed a significant protective effect on NSCLP at both genotype (WW versus WI: odds ratio [OR] = 0.54, 95% confidence interval [CI] = 0.31 to 0.95, P = .149) and allele levels (W versus I: OR = 0.56, 95% CI = 0.32 to 0.96, P = .033). CONCLUSIONS: The current study observed significant differences in the frequency of the CBS 844ins68 allele across populations. There is a significant association between CBS c.844ins68 polymorphism and cleft lip and palate in the Indian population. Additional studies are warranted to identify the functional variants in the genes controlling homocysteine as etiological contributors to the formation of oral clefts.

Significant association of MTHFD1 1958G>A single nucleotide polymorphism with nonsyndromic cleft lip and palate in Indian population.

OBJECTIVE: Nonsyndromic cleft lip and palate (NSCLP) is genetically distinct from those with syndromic clefts, and accounts for ~70% of cases with Oral clefts. Folate, or vitamin B9, is an essential nutrient in our diet. Allelic variants in genes involved in the folate pathway might be expected to have an impact on risk of oral clefts. Given the key role of methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) in folate metabolism, it would be of significant interest to assess its role in NSCLP etiology. STUDY DESIGN: The present study aims at examining the association between MTHFD1 1958G>A polymorphism and NSCLP risk by conducting a case-control study in south Indian population. Our sample comprised of 142 cases with nonsyndromic clefts and 141 controls without clefts or family history of clefting. The MTHFD1 1958G>A polymorphism was genotyped using PCR-RFLP. RESULTS: An increased risk was found for the heterozygous 1958GA (OR=2.44; P=0.020) and homozygous 1958AA (OR=2.45; P=0.012) genotypes in the children. When the dominant model (AG+AA vs GG) was applied the risk remained the same as co-dominant model, but the level of significance increased (OR=2.44; P=0.002). CONCLUSION: The results indicated the MTHFD1 1958G>A polymorphism to be one of the important genetic determinants of NSCLP risk in South Indian subjects.

Genetic variations at 10q26 regions near FGFR2 gene and its association with non-syndromic cleft lip with or without cleft palate.

OBJECTIVES: In our study, we focussed on three SNPs in the non-coding regions near FGFR2 gene, as studies on non-coding variants in the genome are the novel trends to identify the susceptible loci for nonsyndromic cleft lip with or without cleft palate (NSCL/P). FGFR2 gene is selected as a candidate gene based on knock out animal models and the role played in syndromic forms of clefting. FGFR2 gene also plays an important role in FGF signaling pathway during craniofacial development. METHODS: In the present study 148 case-parent triads were assessed for three SNPs rs10749408, rs11199874 and rs10788165 near FGFR2 gene by using TaqMan allelic discrimination method. Transmission disequilibrium test (TDT) was used to find the allelic association. Linkage disequilibrium (LD) between the markers was analysed using Haploview program 4.2. Haplotype transmission effects were estimated using FAMHAP package. The possible parent-of-origin effects were assessed by likelihood based approach. RESULTS: TDT analysis of three SNPs failed to show significant transmission disortion from heterozygous parents to the affected child and are not associated with NSCL/P. Linkage disequilibrium analysis showed strong LD between rs11199874 and rs10788165 SNPs. In the haplotype TDT analysis, GG haplotype of rs11199874-rs10788165 showed significant undertransmission to affected child. No significant parent-of-origin effects were observed. CONCLUSION: The present study on noncoding variants near FGFR2 gene is not associated with NSCL/P. As the numbers of triads included in the study are less, further studies are needed including large sample size to find association with NSCL/P.

First report of THOC6 related intellectual disability (Beaulieu Boycott Innes syndrome) in two siblings from India.

THOC6 is a newly described causal gene for an autosomal recessive intellectual disability (ID) - Beaulieu Boycott Innes syndrome (BBIS) (OMIM # 613680). It is characterized by ID with dysmorphic facies, genitourinary, cardiac anomalies, and dentition problems. Here, we report the first two siblings of BBIS from the Indian subcontinent with previously unreported skeletal anomalies such as Sprengel shoulder, calcaneo valgus deformity, radioulnar dysostosis, and overlapping toes. Whole exome sequencing (WES) identified previously reported three missense variants (p.Trp100Arg, p.Val234Leu, p.Gly275Asp) in THOC6. THOC6 is a subunit of TRanscription and EXport (TREX) complex involved in mRNA transcription, processing, and nuclear export of spliced mRNAs and has a potential role in neurodevelopment. Till date, only 12 patients with BBIS have been reported. This report reviews the phenotypic and genetic data of known BBIS cases in addition to the new phenotypic features, thereby expanding the phenotype of this rare syndrome.

IRF6 rs2235375 single nucleotide polymorphism is associated with isolated non-syndromic cleft palate but not with cleft lip with or without palate in South Indian population.

INTRODUCTION: Transcription factors are very diverse family of proteins involved in activating or repressing the transcription of a gene at a given time. Several studies using animal models demonstrated the role of transcription factor genes in craniofacial development. OBJECTIVE: We aimed to investigate the association of IRF6 intron-6 polymorphism in the non-syndromic cleft lip with or without palate in a South Indian population. METHODS: 173 unrelated nonsyndromic cleft lip with or without cleft palate patients and 176 controls without clefts patients were genotyped for IRF6 rs2235375 variant by allele-specific amplification using the KASPar single nucleotide polymorphism genotyping system. The association between interferon regulatory factor-6 gene intron-6 dbSNP208032210:g.G>C (rs2235375) single nucleotide polymorphism and non-syndromic cleft lip with or without palate risk was investigated by chi-square test. RESULTS: There were significant differences in genotype or allele frequencies of rs2235375 single nucleotide polymorphism between controls and cases with non-syndromic cleft lip with or without palate. IRF6 rs2235375 variant was significantly associated with increased risk of non-syndromic cleft lip with or without palate in co-dominant, dominant (OR: 1.19; 95% CI 1.03-2.51; p=0.034) and allelic models (OR: 1.40; 95% CI 1.04-1.90; p=0.028). When subset analysis was applied significantly increased risk was observed in cleft palate only group (OR dominant: 4.33; 95% CI 1.44-12.97; p=0.005). CONCLUSION: These results suggest that IRF6 rs2235375 SNP play a major role in the pathogenesis and risk of developing non-syndromic cleft lip with or without palate.

Relationship between reduced folate carrier gene polymorphism and non-syndromic cleft lip and palate in Indian population.

OBJECTIVE: Folate metabolism involves absorption, transport, modifications and interconversions of folates. The reduced folate carrier does not participate directly in folate metabolism but plays a major role in intracellular transport of metabolically active 5-methyltetrahydrofolate and maintains the intracellular concentrations of folate. The purpose of this study was to identify the prevalence of reduced folate carrier 1 (RFC1) A80G polymorphism and to further delineate its association with non-syndromic cleft lip and palate (NSCLP) in a south Indian population. METHODS: In the present case-control study, we studied RFC1 gene A80G polymorphism to evaluate its impact on NSCLP risk in south Indian population. Blood samples of 142 cases with NSCLP and 141 controls were collected and genotyped using PCR-RFLP. RESULTS: The genotype distribution in the control group followed Hardy-Weinberg equilibrium (p = 0.633). The G allele frequency of cases was 64.8% (184/284) and was significantly lower than that found in the control group 56.4% (160/282). The genotype distributions between NSCLP cases and controls was not significantly different (p = 0.131). The allelic model significantly increased the risk of NSCLP (G versus A; OR = 1.40; 95% CI: 1.00-1.97; p = 0.050). In subgroup analysis, the A80G variant showed significant association for the CLP group in dominant and allelic models. CONCLUSIONS: Altogether, our findings support the hypothesis that RFC1 A80G variant may contribute to NSCLP susceptibility in a south Indian population.

Evidence of the involvement of the polymorphisms near MSX1 gene in non-syndromic cleft lip with or without cleft palate.

OBJECTIVE: Non-syndromic cleft lip, with or without cleft palate (NSCL/P) is a common craniofacial birth defect, characterised by an incomplete separation between nasal and oral cavities without any other congenital anomaly in humans. Several genes which play a role in cell differentiation, migration, growth and apoptosis, have been associated with clefting. The purpose of this study was to investigate the association between single-nucleotide polymorphisms (SNPs) near MSX1 gene and NSCL/P among South Indian population. METHODS: A case-control analysis of five single nucleotide polymorphisms near MSX1 gene (rs11726039, rs868257, rs6446693, rs1907998 and rs6832405) was carried out in 173 patients with NSCL/P and 176 unaffected controls to determine their association with NSCL/P. RESULTS: All SNPs were polymorphic in the study population. Comparisons of allele and genotype frequencies revealed that the C variant allele and the TC/CC genotypes of rs11726039 was significantly higher in controls than in the NSCL/P group (OR: 0.63; 95% CI: 0.41-0.097; p=0.037). However, neither of these findings remained significant after Bonferroni correction for multiple comparisons. The frequencies of rs868257, rs6446693, rs1907998 and rs6832405 minor alleles and genotypes were similar between the control and NSCL/P groups. No significant linkage disequilibrium (LD) was observed. Genotype-genotype interaction and the haplotype analysis did not reveal any significant association with NSCL/P. CONCLUSIONS: The study results were suggestive of a positive association between MSX1 rs11726039 and NSCL/P in the South Indian population.

SATB2 gene variants in non-syndromic cleft lip with or without cleft palate in Indian population.

OBJECTIVES: Non-syndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common craniofacial birth defects and little is known about its aetiology. Initial studies of cytogenetic analysis provided the clues for possible genes involved in the pathogenesis of NSCL/P. This approach led to the identification of SATB2 gene on 2q32-q33. The aim of this study was to determine the association between SATB2 mutations and NSCL/P. MATERIALS AND METHODS: The rs137853127, rs200074373 and rs1992950 mutations of the SATB2 gene were investigated in 173 patients with NSCL/P and 176 normal controls using Kbioscience KASPar chemistry, which is a competitive allele-specific PCR SNP genotyping system. RESULTS: The mutations in exon 6 (rs137853127 and rs200074373) were monomorphic, the intronic variant (rs1992950) was polymorphic and genotype distribution was in agreement with Hardy-Weinberg equilibrium. The rs1992950 genotype distribution is not statistically significant between NSCL/P and controls. CONCLUSION: Our findings suggest that the SATB2 gene variations do not contribute to the development of NSCL/P in the south Indian population.

MTHFR C677T and A1298C polymorphisms and risk of nonsyndromic orofacial clefts in a south Indian population.

OBJECTIVES: Several lines of evidence suggest that the decrease in folate in periconceptional period or maternal use of folate antagonists has been associated with a higher risk of orofacial clefts (OFCs). MTHFR is a critical enzyme in folate metabolism that catalyzes the irreversible conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, thus playing a vital role in DNA synthesis and DNA methylation. The aim of our study was to determine whether there is any association between the susceptibility to Nonsyndromic cleft lip with or without cleft palate (NSCL/P) amongst the variations of MTHFR genotypes in South Indian population. METHODS: Our sample comprised 123 cases with NSCL/P and 141 controls without clefts or family history of clefting. The most common polymorphisms C677T (rs1801133) and A1298C (rs1801131) on the MTHFR gene were screened for the genotypes using PCR-RFLP. RESULTS: Both C677T and A1298C are polymorphic with minor allele frequencies of 0.131 and 0.429, respectively, for controls. Genotype data in control and cleft groups are following the Hardy Weinberg Equilibrium. There were no significant differences in genotypes of both polymorphisms between controls and NSCL/P. The pairwise LD values (D' and r(2)) between C677T and A1298C are 1.0 and 0.096 respectively indicating no significant LD between these two SNPs. Haplotype phenotype analysis did not show the evidence for association. Gene-gene interaction showed the distribution of the observed combinations of the two MTHFR polymorphisms was not different between NSCL/P and controls (p=0.887). CONCLUSIONS: Our results do not support the hypothesis, that variants in the MTHFR gene confer a risk for NSCL/P in the South Indian population.

TCF7L2 rs7903146 polymorphism and diabetic nephropathy association is not independent of type 2 diabetes--a study in a south Indian population and meta-analysis.

Diabetic nephropathy (DN) is a chronic microangiopathic complication of both type 1 (T1DM) and type 2 diabetes mellitus (T2DM). The TCF7L2 gene has been reported to be associated with type 2 diabetes risk. We aimed to investigate the impact of TCF7L2 gene on the susceptibility of T2DM and DN in a south Indian population. Plus to evaluate the association of rs7903146 in the TCF7L2 gene with T2DM in the Indian population. The subjects recruited for this included 55 diabetic cases with diabetic nephropathy, 68 diabetic cases without nephropathy, and 82 non-diabetic healthy controls. Genomic DNA was isolated from blood and genotyping of TCF7L2 rs7903146 was performed by PCR-RFLP analysis. A literature survey was carried out into the effect of rs7903146 on genetic susceptibility to T2DM in Indian populations and we then performed a meta-analysis in order to evaluate its association with T2DM. Analysis of TCF7L2 rs7903146 in normal controls and diabetics with or without nephropathy demonstrated that the 'T' allele is associated with both diabetes (p = 0.049) and DN (p = 0.024), but this association is not independent of T2DM. Meta-analysis showed that the mutant allele and genotypes are associated with T2DM in Indian populations. In summary, a significant association exists between the 'T' allele and DN, but this association is not independent of T2DM. Pooled meta-analysis of studies on rs7903146 and T2DM confirmed that rs7903146 is significantly associated with susceptibility to T2DM in Indian populations.

IRF6 rs2235375 single nucleotide polymorphism is associated with isolated non-syndromic cleft palate but not with cleft lip with or without palate in South Indian population / Polimorfismo de nucleotídeo único do gene IRF6 rs2235375 está associado com à fenda palatina isolada não sindrômica, mas não com fenda labial com ou sem fenda palatina em população do sul da Índia

Abstract Introduction Transcription factors are very diverse family of proteins involved in activating or repressing the transcription of a gene at a given time. Several studies using animal models demonstrated the role of transcription factor genes in craniofacial development. Objective We aimed to investigate the association of IRF6 intron-6 polymorphism in the non-syndromic cleft lip with or without palate in a South Indian population. Methods 173 unrelated nonsyndromic cleft lip with or without cleft palate patients and 176 controls without clefts patients were genotyped for IRF6 rs2235375 variant by allele-specific amplification using the KASPar single nucleotide polymorphism genotyping system. The association between interferon regulatory factor-6 gene intron-6 dbSNP208032210:g.G>C (rs2235375) single nucleotide polymorphism and non-syndromic cleft lip with or without palate risk was investigated by chi-square test. Results There were significant differences in genotype or allele frequencies of rs2235375 single nucleotide polymorphism between controls and cases with non-syndromic cleft lip with or without palate. IRF6 rs2235375 variant was significantly associated with increased risk of non-syndromic cleft lip with or without palate in co-dominant, dominant (OR: 1.19; 95% CI 1.03-2.51; p = 0.034) and allelic models (OR: 1.40; 95% CI 1.04-1.90; p = 0.028). When subset analysis was applied significantly increased risk was observed in cleft palate only group (OR dominant: 4.33; 95% CI 1.44-12.97; p = 0.005). Conclusion These results suggest that IRF6 rs2235375 SNP play a major role in the pathogenesis and risk of developing non-syndromic cleft lip with or without palate.

Resumo Introdução Fatores de transcrição constituem uma família de proteínas muito diversa envolvida na ativação ou repressão da transcrição de um gene, em um determinado momento. Vários estudos usando modelos animais demonstraram o papel dos genes do fator de transcrição no desenvolvimento craniofacial. Objetivo Nosso objetivo foi investigar a associação do polimorfismo IRF6 intron-6 na fenda labial não sindrômica com ou sem fenda palatina em uma população do sul da Índia. Método Um total de 173 pacientes com fenda labial não sindrômica com ou sem fenda palatina e 176 controles sem fendas foram genotipados para a variante IRF6 rs2235375 por amplificação alelo-específica utilizando o sistema KASPar de genotipagem de polimorfismo de nucleotídeo único. A associação entre o polimorfismo de nucleotídeo único Fator 6 Regulatório do Interferon (IRF6) intron-6 dbSNP208032210:g.G>C (rs2235375) e o risco de fenda labial não sindrômica com ou sem fenda palatina foi investigado pelo teste qui-quadrado. Resultados Houve diferenças significativas nas frequências de genótipos ou alelos do rs2235375 SNP entre controles e casos com fenda labial não sindrômica com ou sem fenda palatina. A variante IRF6 rs2235375 foi significativamente associada ao aumento do risco de fenda labial não sindrômica com ou sem fenda palatina em modelos codominantes, dominantes (OR: 1,19; IC 95%: 1,03-2,51; p = 0,034) e alélicos (OR: 1,40; IC 95%: 1,04-1,90; p = 0,028). Quando a análise do subgrupo foi realizada, um risco significativamente aumentado foi observado no grupo Fenda Palatina Isolada (OR dominante: 4,33; IC 95%: 1,44-12,97; p = 0,005). Conclusões Esses resultados sugerem que o polimorfismo de nucleotídeo único IRF6 rs2235375 desempenha um papel importante na patogênese e no risco de desenvolvimento de fenda labial não sindrômica com ou sem fenda palatina.