Genome-Wide Scan for Parent-of-Origin Effects in a sub-Saharan African Cohort With Nonsyndromic Cleft Lip and/or Cleft Palate (CL/P).

OBJECTIVE: Nonsyndromic cleft lip and/or cleft palate (NSCL/P) have multifactorial etiology where genetic factors, gene-environment interactions, stochastic factors, gene-gene interactions, and parent-of-origin effects (POEs) play cardinal roles. POEs arise when the parental origin of alleles differentially impacts the phenotype of the offspring. The aim of this study was to identify POEs that can increase risk for NSCL/P in humans using a genome-wide dataset. METHODS: The samples (174 case-parent trios from Ghana, Ethiopia, and Nigeria) included in this study were from the African only genome wide association studies (GWAS) that was published in 2019. Genotyping of individual DNA using over 2 million multiethnic and African ancestry-specific single-nucleotide polymorphisms from the Illumina Multi-Ethnic Genotyping Array v2 15070954 A2 (genome build GRCh37/hg19) was done at the Center for Inherited Diseases Research. After quality control checks, PLINK was employed to carry out POE analysis employing the pooled subphenotypes of NSCL/P. RESULTS: We observed possible hints of POEs at a cluster of genes at a 1 mega base pair window at the major histocompatibility complex class 1 locus on chromosome 6, as well as at other loci encompassing candidate genes such as ASB18, ANKEF1, AGAP1, GABRD, HHAT, CCT7, DNMT3A, EPHA7, FOXO3, lncRNAs, microRNA, antisense RNAs, ZNRD1, ZFAT, and ZBTB16. CONCLUSION: Findings from our study suggest that some loci may increase the risk for NSCL/P through POEs. Additional studies are required to confirm these suggestive loci in NSCL/P etiology.

Missense Variants Within GJB2 Gene Locus and the Risk of Hearing Defects in Nonsyndromic Cleft Lip and Palate.

AIM: The aim of the study was to investigate the role of variants in GJB2 gene in the etiology of hearing defects in nonsyndromic cleft lip/palate. METHOD: Saliva samples were obtained from cases (subjects with orofacial clefts) and control (subjects without orofacial clefts) who consented to the study. Deoxyribonucleic acid (DNA) was extracted using standardized protocol at Butali Lab (Iowa, IA). Primers for the coding region of GJB2 was designed using Primer 3 (http://bioinfo.ut.ee/primer3-0.4.0/) and optimized in the Butali lab using a gradient polymerase chain reaction to determine the annealing temperature for each primer set (forward and reverse). We measured the DNA concentration using Qubit and XY genotyping done for quality control. A concentration of 5 ng/µL of DNA was used for Sanger sequencing. RESULTS: A total of 150 subjects were sequenced (66 cases; 84 controls). Mutations in GJB2 gene were detected in 2 individuals with cleft palate. We found p.Arg165Trp variant in 1 case and p.Leu81Val variant in the second case. Although p.Arg165Trp was predicted to be either benign or tolerated by SIFT/POLYPHEN, the single nucleotide change from C>T, that is, CGG>TGG leads to a premature stop codon preventing the protein formation. The p.Leu81Val variant was predicted to be probably damaging/ deleterious. CONCLUSIONS: The present study implicates variants in the GJB2 gene in the etiology of hearing defects in nonsyndromic cleft lip and palate in the Nigerian population. Screening for variations in GJB2 gene is important for genetic counseling especially in high-risk families.

Correlation Between Height and Impacted Third Molars and Genetics Role in Third Molar Impaction.

AIM: This study sought to evaluate the relationship between height of an individual and the presence of impaction of maxillary and mandibular third molars, and to determine the role of genetics in third molar impaction. MATERIALS AND METHODS: This was a case-control study, with cases consisted of 200 subjects with third molar impactions; and 200 controls without third molar impactions. Height of subjects was measured, and saliva samples were collected from all the subjects. DNA was extracted from saliva samples. To investigate the role of selected genes in the etiology of third molar impactions, Taqman Genotyping using SNPs identified for jaw growth, height and tooth agenesis was employed. Five candidate genes were investigated using 11 markers (SNPs). RESULTS: The mean height of cases was significantly lower than that of the control subjects (p = 0.04). No difference was found in allele frequency between cases and controls for 10 of the 11 SNPs. However, for rs6504591 the p value was near significance (p = 0.07) with odd ratio of 2.131. Subjects with lower third molar impactions were significantly shorter than those who have fully erupted third molars. CONCLUSIONS: Subjects with lower third molar impactions were significantly shorter than those who have fully erupted third molars. We observed that individuals with third molar impaction tend to have T allele at the locus, suggesting that the T allele at the locus may increase the risk for having an impacted third molar. The rs6504591 G/T variation on human chromosome 17 (WNT9B gene) appears to increase risk by twofolds for impaction albeit with inability to detect significance due to small sample size.

Congenital heart defects in orofacial cleft: A prospective cohort study.

BACKGROUND: Congenital heart defects (CHDs) are one of the most common associated anomalies in patients with an orofacial cleft (OFC). However, few studies have shown the association between cleft type and CHDs in our population. This study aimed to assess the prevalence of CHDs in a cohort of OFC patients at a tertiary health facility in Nigeria, as well as assess the risk of CHD by OFC type. MATERIALS AND METHODS: This was a prospective study design. Patients with an OFC were consecutively enrolled at a single OFC treatment facility. All subjects were assessed by a paediatric cardiologist and had echocardiography done. They were categorised based on the presence of CHDs, as well as the OFC phenotypic type (cleft lip and/or alveolus, cleft lip and palate and cleft palate only). Statistical analysis was done using STATA version 14 (College Station, Texas), and significance was set at P < 0.05. RESULTS: A total of 150 subjects enrolled in the study over a period of 2 years (2018-2020). The median age of subjects was 6 months (interquartile range: 2-24), and 54.7% were female. The prevalence of CHDs in the subjects reviewed was 30.7%. Based on the severity of CHDs, the majority presented with simple defects (95.6%). Overall, the most common presentation was patent foramen ovale (12.7%), followed by septal defects (8.0%). There was no significant association between cleft type and the odds of a CHD. CONCLUSION: The study reports a relatively high prevalence of CHDs in patients with OFC; however, there was no association between the risk of CHD by cleft type. Although a majority of CHDs may pose a low operative risk, cardiac evaluation is recommended for all cases of OFC to aid the identification of potentially high-risk cases.