Variant analyses of candidate genes in orofacial clefts in multi-ethnic populations.

OBJECTIVES: Cleft lip with/without cleft palate and cleft palate only is congenital birth defects where the upper lip and/or palate fail to fuse properly during embryonic facial development. Affecting ~1.2/1000 live births worldwide, these orofacial clefts impose significant social and financial burdens on affected individuals and their families. Orofacial clefts have a complex etiology resulting from genetic variants combined with environmental covariates. Recent genome-wide association studies and whole-exome sequencing for orofacial clefts identified significant genetic associations and variants in several genes. Of these, we investigated the role of common/rare variants in SHH, RORA, MRPL53, ACVR1, and GDF11. MATERIALS AND METHODS: We sequenced these five genes in 1255 multi-ethnic cleft lip with/without palate and cleft palate only samples in order to find variants that may provide potential explanations for the missing heritability of orofacial clefts. Rare and novel variants were further analyzed using in silico predictive tools. RESULTS: Ninteen total variants of interest were found, with variant types including stop-gain, missense, synonymous, intronic, and splice-site variants. Of these, 3 novel missense variants were found, one in SHH, one in RORA, and one in GDF11. CONCLUSION: This study provides evidence that variants in SHH, RORA, MRPL53, ACVR1, and GDF11 may contribute to risk of orofacial clefts in various populations.

Co-occurrence of orofacial clefts and clubfoot phenotypes in a sub-Saharan African cohort: Whole-exome sequencing implicates multiple syndromes and genes.

BACKGROUND: Orofacial clefts (OFCs) are congenital malformations of the face and palate, with an incidence of 1 per 700 live births. Clubfoot or congenital talipes equinovarus (CTEV) is a three-dimensional abnormality of the leg, ankle, and feet that leads to the anomalous positioning of foot and ankle joints and has an incidence of 1 per 1000 live births. OFCs and CTEV may occur together or separately in certain genetic syndromes in addition to other congenital abnormalities. Here, we sought to decipher the genetic etiology of OFC and CTEV that occurred together in six probands. METHODS: At the time of recruitment, the most clinically obvious congenital anomalies in these individuals were the OFC and CTEV. We carried out whole-exome sequencing (WES) on DNA samples from probands and available parents employing the Agilent SureSelect XT kit and Illumina HiSeq2500 platform, followed by bioinformatics analyses. WES variants were validated by clinical Sanger Sequencing. RESULTS: Of the six probands, we observed probable pathogenic genetic variants in four. In three probands with probable pathogenic genetic variants, each individual had variants in three different genes, whereas one proband had probable pathogenic variant in just one gene. In one proband, we observed variants in DIS3L2, a gene associated with Perlman syndrome. A second proband had variants in EPG5 (associated with Vici Syndrome), BARX1 and MKI67, while another proband had potentially etiologic variants in FRAS1 (associated with Fraser Syndrome 1), TCOF1 (associated with Treacher Collins Syndrome 1) and MKI67. The last proband had variants in FRAS1, PRDM16 (associated with Cardiomyopathy, dilated, 1LL/Left ventricular noncompaction 8) and CHD7 (associated with CHARGE syndrome/Hypogonadotropic hypogonadism 5 with or without anosmia). CONCLUSION: Our results suggest that clubfoot and OFCs are two congenital abnormalities that can co-occur in certain individuals with varying genetic causes and expressivity, warranting the need for deep phenotyping.