RESUMEN
OBJECTIVES: The interaction between genomics, genetic and environmental factors have been implicated in non-syndromic orofacial cleft development. In the current study, we investigated the contributions of rare and novel genetic variants in known cleft genes using whole exome sequencing (WES) data of Indonesians with non-syndromic orofacial clefts. DESIGN: WES was conducted on 6 individuals. Variants in their exons were called and annotated. These variants were filtered for novelty and rarity using MAF of 0 and 1%. SETTING: Hospital in Indonesia. PATIENTS/PARTICIPANTS: Indonesians with non-syndromic orofacial clefts. INTERVENTIONS: Deleterious variants were prioritized. Pathogenic amino acid changes effect on protein structure and function were identified using HOPE. MAIN OUTCOME MEASURE(S): Rare and novel variants in known cleft genes were filtered and their deleteriousness were predicted using polyphen, SIFT and CADD. RESULTS: We identified rare (MAF <1%) deleterious variants in 4 craniofacial genes namely MMACHC (rs371937044, MAF = 0.00011). SOS1 (rs190222208, MAF = 0.00045), TULP4 (rs199583035, MAF = 0.067), and MTHFD1L (rs143492706, MAF = 0.0044). MMACHC has a mouse knockout model with facial cleft and failure of palatal fusion. The individual with variant in MMACHC presented with nsCPO. CONCLUSIONS: Our study provides additional evidence for the role of TULP4, SOS1, MTHFD1L and MMACHC genes in nsOFC development. This is the first time MMACHC is implicated in nsOFC development in humans.
RESUMEN
BACKGROUND: During the early embryological development of the face, complex orofacial failure results in a non-syndromic cleft lip and palate (NS CLP). The interferon regulatory factor 6 gene (IRF6) rs2235371 is a non-synonymous polymorphism that is one of the strong candidate genes associated with NS CLP. OBJECTIVES: The purpose of this study was to determine IRF6 rs2235371 as a risk factor for NS CLP and its phenotypes, including complete unilateral cleft lip and palate (CUCLP), bilateral cleft lip and palate (BCLP), cleft lip only (CL), and cleft palate only (CP), as well as to examine the effect of the polymorphism on the IRF6 mRNA expression levels among the Deutero-Malay race in Indonesia. MATERIAL AND METHODS: This study used a case-control design and enrolled 264 samples, including 158 NS CLP cases (42 NS CUCLP, 34 NS BCLP, 33 NS CL, and 49 NS CP) and 106 control subjects. DNA was extracted from venous blood, and then subjected to polymerase chain reaction (PCR) and sequencing. The odds ratio (OR) was used to determine the risk factor for NS CLP and its phenotypes. The Livak, KruskalWallis and Mann-Whitney U tests were used to determine mRNA expression levels in the oral epithelium, followed by real-time quantitative PCR (RT-qPCR). RESULTS: Among all of the NS CLP cases, in the NS CP phenotype, OR for the A mutant allele and the GA genotype was 2,492 (p = 0.017) and 2,114 (p = 0.048), respectively. The IRF6 mRNA expression level of the GA genotype was higher in the NS CP subjects as compared to the GG genotype (p = 0.031). CONCLUSIONS: The IRF6 rs2235371 polymorphism is associated with the NS CP phenotype in DeuteroMalay patients from Indonesia and it affects the IRF6 mRNA expression level.