Identification of de novo variants in nonsyndromic cleft lip with/without cleft palate patients with low polygenic risk scores.

BACKGROUND: Nonsyndromic cleft lip with/without cleft palate (nsCL/P) is a congenital malformation of multifactorial etiology. Research has identified >40 genome-wide significant risk loci, which explain less than 40% of nsCL/P heritability. Studies show that some of the hidden heritability is explained by rare penetrant variants. METHODS: To identify new candidate genes, we searched for highly penetrant de novo variants (DNVs) in 50 nsCL/P patient/parent-trios with a low polygenic risk for the phenotype (discovery). We prioritized DNV-carrying candidate genes from the discovery for resequencing in independent cohorts of 1010 nsCL/P patients of diverse ethnicities and 1574 population-matched controls (replication). Segregation analyses and rare variant association in the replication cohort, in combination with additional data (genome-wide association data, expression, protein-protein-interactions), were used for final prioritization. CONCLUSION: In the discovery step, 60 DNVs were identified in 60 genes, including a variant in the established nsCL/P risk gene CDH1. Re-sequencing of 32 prioritized genes led to the identification of 373 rare, likely pathogenic variants. Finally, MDN1 and PAXIP1 were prioritized as top candidates. Our findings demonstrate that DNV detection, including polygenic risk score analysis, is a powerful tool for identifying nsCL/P candidate genes, which can also be applied to other multifactorial congenital malformations.

Exome sequencing in large, multiplex bipolar disorder families from Cuba.

Bipolar disorder (BD) is a major psychiatric illness affecting around 1% of the global population. BD is characterized by recurrent manic and depressive episodes, and has an estimated heritability of around 70%. Research has identified the first BD susceptibility genes. However, the underlying pathways and regulatory networks remain largely unknown. Research suggests that the cumulative impact of common alleles with small effects explains only around 25-38% of the phenotypic variance for BD. A plausible hypothesis therefore is that rare, high penetrance variants may contribute to BD risk. The present study investigated the role of rare, nonsynonymous, and potentially functional variants via whole exome sequencing in 15 BD cases from two large, multiply affected families from Cuba. The high prevalence of BD in these pedigrees renders them promising in terms of the identification of genetic risk variants with large effect sizes. In addition, SNP array data were used to calculate polygenic risk scores for affected and unaffected family members. After correction for multiple testing, no significant increase in polygenic risk scores for common, BD-associated genetic variants was found in BD cases compared to healthy relatives. Exome sequencing identified a total of 17 rare and potentially damaging variants in 17 genes. The identified variants were shared by all investigated BD cases in the respective pedigree. The most promising variant was located in the gene SERPING1 (p.L349F), which has been reported previously as a genome-wide significant risk gene for schizophrenia. The present data suggest novel candidate genes for BD susceptibility, and may facilitate the discovery of disease-relevant pathways and regulatory networks.

Congenital diaphragmatic hernia in a case of Cat eye syndrome.

Our findings extend the phenotypic spectrum of Cat eye syndrome, a disorder with wide clinical variability. The potentially life-threatening complications of congenital diaphragmatic hernia should be considered in genetic counseling and prenatal diagnostic.

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.

Mosaic tetrasomy 14pter-q13 due to a supernumerary isodicentric derivate of proximal chromosome 14q.

Tetrasomy of proximal 14q is an extremely rare condition and has never been reported to be associated with survival. We here report on the first case of mosaic tetrasomy of 14pter-q13 due to a de-novo supernumerary pseudoisodicentric chromosome in a 2-year-old boy with multiple dysmorphisms and malformations. The marker was detectable in nearly 25% of lymphocytes as well as in cells from buccal mucosa. Detailed fluorescence in situ hybridization (FISH) analyses allowed the characterization of the marker to entirely consist of proximal 14q material and to be symmetric. The pattern of clinical features in our patient only slightly correspond to that of patients with trisomy of proximal 14q, but further cases are needed to define whether tetrasomy of proximal 14q is a separate entity.

New trends in chromosomal investigation in children with cardiovascular malformations.

We investigated a group of 376 children, seen over a period of 7 years with different types of congenital cardiovascular defects, to assess the presence of chromosomal aberrations. The diagnostic approach, achieved in 3 consecutive steps, revealed conventional chromosomal aberrations in 30 of the patients (8%) excluding trisomies 13, 18, 21. Fluorescence in situ hybridisation for microdeletions showed 51 microdeletions (15%), with 43 patients having deletions of 22q11.2, 7 patients with deletion of 7q11.23, and 1 patient with deletion of 4p16.3. In 23 patients with additional clinical abnormalities, we carried out a subtelomeric screening. This revealed, in two cases (9%), different subtelomeric aberrations, namely deletions of 1p and of 1q. Thus, subtelomeric screening proved to be a very valuable as a new diagnostic approach. Our approach to genetic investigation in three phases makes it possible to detect a high rate of pathologic karyotypes in patients with congenital cardiovascular malformations, thus guaranteeing more effective genetic counselling of the families, and a more precise prognosis for the patient.