Liliane Todeschini de Souza

A multicentric association study between 39 genes and nonsyndromic cleft lip and palate in a Brazilian population.

PURPOSE The aim of this study was to use the TaqMan OpenArray system to evaluate associations between 39 genes and the etiology of nonsyndromic cleft lip and palate (NSCLP) in a Brazilian population. MATERIAL AND METHODS This case-control association study was designed with 80.11% statistical power according to logistic regression (GPOWER software). The case group had 182 patients with NSCLP enrolled in the Brazilian Database on Orofacial Clefts. The controls included 355 healthy individuals with no history of oral clefting in the past three generations. All samples were genotyped for 253 tag single nucleotide polymorphisms (tagSNPs) in 39 genes, including two that had recently been associated with this process. The association analysis was performed using logistic regression and stepwise regression. The results were corrected for multiple testing [Bonferroni correction and False Discovery Rate (FDR)]. RESULTS Twenty-four SNPs in 16 genes were significantly associated with the etiology of NSCLP, including MSX1, SPRY1, MSX2, PRSS35, TFAP2A, SHH, VAX1, TBX10, WNT11, PAX9, BMP4, JAG2, AXIN2, DVL2, KIF7, and TCBE3. Stepwise regression analysis revealed that 11 genes contributed to 15.5% of the etiology of NSCLP in the sample. CONCLUSION This is the first study to associate KIF7 and TCEB3 with the etiology of NSCLP. New technological approaches using the same design should help to identify further etiological susceptibility variants.

Preliminary Analysis of the Nonsynonymous Polymorphism rs17563 in BMP4 Gene in Brazilian Population Suggests Protection for Nonsyndromic Cleft Lip and Palate.

Cleft lip with or without palate (CL±P) is common congenital anomalies in humans. Experimental evidence has demonstrated that bone morphogenetic protein 4 gene (Bmp4) is involved in the etiology of CL±P in animal models. The nonsynonymous polymorphism rs17563 T>C (p.V152A) in the BMP4 gene has been associated to the risk of nonsyndromic CL±P in Chinese population and microforms from different ethnic backgrounds. The aim of this study was to investigate the role of BMP4 gene in CL±P in Brazilian sample using genetic association approach. Our sample was composed by 123 patients with nonsyndromic CL±P and 246 controls, in which absence of CL±P was confirmed in 3 generations. The rs17563 polymorphism was genotyped by PCR-RFLP technique. Logistic regression was performed to evaluate allele and genotype association. Our data showed statistical power to detect association (86.83%) in this sample. Logistic regression results showed significant association between C allele and CL±P (P = 0.00018, OR = 0.40, and 95% CI = 0.25–0.65), as well as CC genotype and CL±P (P = 0.00018, OR = 0.35, and 95% CI = 0.19–0.66). So, there is a strong association between nonsyndromic CL±P and BMP4 rs17563 polymorphism in our sample and the C allele had a protective effect against the occurrence of nonsyndromic CL±P.

MSX1 gene and nonsyndromic oral clefts in a Southern Brazilian population

Nonsyndromic oral clefts (NSOC) are the most common craniofacial birth defects in humans. The etiology of NSOC is complex, involving both genetic and environmental factors. Several genes that play a role in cellular proliferation, differentiation, and apoptosis have been associated with clefting. For example, variations in the homeobox gene family member MSX1, including a CA repeat located within its single intron, may play a role in clefting. The aim of this study was to investigate the association between MSX1 CA repeat polymorphism and NSOC in a Southern Brazilian population using a case-parent triad design. We studied 182 nuclear families with NSOC recruited from the Hospital de Clínicas de Porto Alegre in Southern Brazil. The polymorphic region was amplified by the polymerase chain reaction and analyzed by using an automated sequencer. Among the 182 families studied, four different alleles were observed, at frequencies of 0.057 (175 bp), 0.169 (173 bp), 0.096 (171 bp) and 0.67 (169 bp). A transmission disequilibrium test with a family-based association test (FBAT) software program was used for analysis. FBAT analysis showed overtransmission of the 169 bp allele in NSOC (P=0.0005). These results suggest that the CA repeat polymorphism of the MSX1 gene may play a role in risk of NSOC in populations from Southern Brazil.

Prevalence of the 35delG mutation in deaf South Brazilian infants submitted to cochlear implantation.

OBJECTIVE Determine the prevalence of 35delG mutation in GJB2 gene in patients with prelingual deafness of no defined etiology whose underwent cochlear implant in the Otolaryngology Department at the Hospital de Clínicas de Porto Alegre and compare the speech recognition index using an open-set of sentences according to the presence or absence of the 35delG mutation. METHODS Cross-sectional study nested in a cohort. Were analyzed 37 patients with indeterminate etiology for deafness that underwent to cochlear implant. DNA was extracted and the mutations were studied using Polymerase Chain Reaction followed by gene sequencing. RESULTS The prevalence of 35delG mutation was 11%. The speech recognition index was 72% in the group with 35delG mutation, and 30% in the group without this mutation (p>0.05). CONCLUSIONS Prevalence of 35delG mutation in this study confirmed findings in the Brazilian literature. There was a clinically significant difference in hearing performance in patients with 35delG. Absence of statistical significance in this result might be attributed to the small number of patients with 35delG in our sample.

TGFA/Taq I polymorphism and environmental factors in non-syndromic oral clefts in Southern Brazil.

We report a study of TGFA/ Taq I polymorphisms and environmental factors in non-syndromic oral cleft in Southern Brazil. Nonsyndromic cleft case-parent triads were recruited to participate. Clinical data was collected with an emphasis on tobacco and alcohol use during pregnancy. DNA was extracted from peripheral blood and TGFA/ Taq I polymorphisms were analyzed by PCR/RFLP with Taq I restriction enzyme. Association of clefts and TGFA/ Taq I polymorphisms was determined using a transmission disequilibrium test (TDT). Association of environmental factors, clefts, and genotypes was evaluated with Fishers exact test. The minor allele frequency was 0.064. We found no evidence of association between TGFA/ Taq I polymorphisms and clefting (TDT p = 0.335). We also found no association between TGFA/ TaqI polymorphisms and environmental factors (alcohol and/or tobacco). Therefore, no evidence was found that TGFA/ Taq I polymorphisms play a role in clefting in this population. No evidence was found that tobacco or alcohol exposure during pregnancy was related to clefting, however a larger sample size is needed to confirm these results.