Sequencing the GRHL3 Coding Region Reveals Rare Truncating Mutations and a Common Susceptibility Variant for Nonsyndromic Cleft Palate.

Nonsyndromic cleft lip with/without cleft palate (nsCL/P) and nonsyndromic cleft palate only (nsCPO) are the most frequent subphenotypes of orofacial clefts. A common syndromic form of orofacial clefting is Van der Woude syndrome (VWS) where individuals have CL/P or CPO, often but not always associated with lower lip pits. Recently, ∼5% of VWS-affected individuals were identified with mutations in the grainy head-like 3 gene (GRHL3). To investigate GRHL3 in nonsyndromic clefting, we sequenced its coding region in 576 Europeans with nsCL/P and 96 with nsCPO. Most strikingly, nsCPO-affected individuals had a higher minor allele frequency for rs41268753 (0.099) than control subjects (0.049; p = 1.24 × 10(-2)). This association was replicated in nsCPO/control cohorts from Latvia, Yemen, and the UK (pcombined = 2.63 × 10(-5); ORallelic = 2.46 [95% CI 1.6-3.7]) and reached genome-wide significance in combination with imputed data from a GWAS in nsCPO triads (p = 2.73 × 10(-9)). Notably, rs41268753 is not associated with nsCL/P (p = 0.45). rs41268753 encodes the highly conserved p.Thr454Met (c.1361C>T) (GERP = 5.3), which prediction programs denote as deleterious, has a CADD score of 29.6, and increases protein binding capacity in silico. Sequencing also revealed four novel truncating GRHL3 mutations including two that were de novo in four families, where all nine individuals harboring mutations had nsCPO. This is important for genetic counseling: given that VWS is rare compared to nsCPO, our data suggest that dominant GRHL3 mutations are more likely to cause nonsyndromic than syndromic CPO. Thus, with rare dominant mutations and a common risk variant in the coding region, we have identified an important contribution for GRHL3 in nsCPO.

Further evidence for deletions in 7p14.1 contributing to nonsyndromic cleft lip with or without cleft palate.

BACKGROUND: Nonsyndromic cleft with or without cleft palate (nsCL/P) is a common birth defect. Although genome-wide association studies (GWAS) have identified numerous risk variants, a considerable fraction of the genetic heritability remains unknown. The aim of the present study was to replicate a previous finding that de novo deletions in a 62 kb region of chromosome 7p14 are a risk factor for nsCL/P, using an independent cohort. METHODS: Data from a published case-control GWAS cohort of 399 patients and 1318 controls were used. Copy number variant (CNV) detection in the 62 kb candidate region of 7p14 was performed using QuantiSNP. Putative CNVs in probands were verified and validated by quantitative polymerase chain reaction. Segregation analyses were performed in family members for whom DNA was available. RESULTS: Within the 62 kb candidate region, a deletion of 7.4 kb showed association with nsCL/P (13/387 cases, 20/1300 controls, plowest = 0.024, odds ratio = 2.22). In all families with a sporadic case (n = 3), the deletion occurred de novo. In multiplex families, both incomplete segregation and incomplete penetrance were observed. CONCLUSION: The present data support the hypothesis that deletions at 7p14 are a common risk factor for nsCL/P. Genome-wide CNV analyses in nsCL/P cohorts are warranted to explore the functional relevance of these deletions and their contribution to nsCL/P, and to determine exact breakpoints. Birth Defects Research (Part A) 106:767-772, 2016. © 2016 Wiley Periodicals, Inc.