Previous studies have shown that copy-number variants (CNVs) contribute to the risk of complex developmental phenotypes. However, the contribution of global CNV burden to the risk of sporadic congenital heart disease (CHD) remains incompletely defined. We generated genome-wide CNV data by using Illumina 660W-Quad SNP arrays in 2,256 individuals with CHD, 283 trio CHD-affected families, and 1,538 controls. We found association of rare genic deletions with CHD risk (odds ratio [OR] = 1.8, p = 0.0008). Rare deletions in study participants with CHD had higher gene content (p = 0.001) with higher haploinsufficiency scores (p = 0.03) than they did in controls, and they were enriched with Wnt-signaling genes (p = 1 × 10(-5)). Recurrent 15q11.2 deletions were associated with CHD risk (OR = 8.2, p = 0.02). Rare de novo CNVs were observed in ~5% of CHD trios; 10 out of 11 occurred on the paternally transmitted chromosome (p = 0.01). Some of the rare de novo CNVs spanned genes known to be involved in heart development (e.g., HAND2 and GJA5). Rare genic deletions contribute ~4% of the population-attributable risk of sporadic CHD. Second to previously described CNVs at 1q21.1, deletions at 15q11.2 and those implicating Wnt signaling are the most significant contributors to the risk of sporadic CHD. Rare de novo CNVs identified in CHD trios exhibit paternal origin bias.

Recurrent rearrangements of chromosome 1q21.1 that occur via non-allelic homologous recombination have been associated with variable phenotypes exhibiting incomplete penetrance, including congenital heart disease (CHD). However, the gene or genes within the ∼1 Mb critical region responsible for each of the associated phenotypes remains unknown. We examined the 1q21.1 locus in 948 patients with tetralogy of Fallot (TOF), 1488 patients with other forms of CHD and 6760 ethnically matched controls using single nucleotide polymorphism genotyping arrays (Illumina 660W and Affymetrix 6.0) and multiplex ligation-dependent probe amplification. We found that duplication of 1q21.1 was more common in cases of TOF than in controls [odds ratio (OR) 30.9, 95% confidence interval (CI) 8.9–107.6); P = 2.2 × 10−7], but deletion was not. In contrast, deletion of 1q21.1 was more common in cases of non-TOF CHD than in controls [OR 5.5 (95% CI 1.4–22.0); P = 0.04] while duplication was not. We also detected rare (n = 3) 100–200 kb duplications within the critical region of 1q21.1 in cases of TOF. These small duplications encompassed a single gene in common, GJA5, and were enriched in cases of TOF in comparison to controls [OR = 10.7 (95% CI 1.8–64.3), P = 0.01]. These findings show that duplication and deletion at chromosome 1q21.1 exhibit a degree of phenotypic specificity in CHD, and implicate GJA5 as the gene responsible for the CHD phenotypes observed with copy number imbalances at this locus.

Congenital poikiloderma is characterized by a combination of mottled pigmentation, telangiectasia, and epidermal atrophy in the first few months of life. We have previously described a South African European-descent family affected by a rare autosomal-dominant form of hereditary fibrosing poikiloderma accompanied by tendon contracture, myopathy, and pulmonary fibrosis. Here, we report the identification of causative mutations in FAM111B by whole-exome sequencing. In total, three FAM111B missense mutations were identified in five kindreds of different ethnic backgrounds. The mutation segregated with the disease in one large pedigree, and mutations were de novo in two other pedigrees. All three mutations were absent from public databases and were not observed on Sanger sequencing of 388 ethnically matched control subjects. The three single-nucleotide mutations code for amino acid changes that are clustered within a putative trypsin-like cysteine/serine peptidase domain of FAM111B. These findings provide evidence of the involvement of FAM111B in congenital poikiloderma and multisystem fibrosis.

Congenital cardiovascular malformation (CVM) exhibits familial predisposition, but most of the specific genetic factors involved are unknown. Postulating that rare variants in genes in critical cardiac developmental pathways predispose to CVM, we systematically surveyed three genes of the bone morphogenetic protein (BMP) signaling pathway for novel variants. Exonic, splice site, and untranslated regions of BMPR1A, BMPR2, and SMAD6 genes were sequenced in 90 unrelated sporadic cases of CVM. One nonsynonymous variant (p.C484F) with predicted functional impact was found in the MAD homology 2 domain of SMAD6, an intracellular inhibitor of BMP signaling. Sequencing this domain in an additional 346 cases of CVM yielded two further nonsynonymous variants (p.P415L and p.A325T). Functional effects of all three SMAD6 mutations were investigated using BMP signaling assays in vitro. Two SMAD6 variants (p.C484F and p.P415L) had significantly (P < 0.05) lower activity than wild-type SMAD6 in inhibiting BMP signaling in a transcriptional reporter assay. In addition, the p.C484F variant had a significantly (P < 0.05) lower capacity to inhibit an osteogenic response to BMP signaling. We conclude that low-frequency deleterious variants in SMAD6 predispose to CVM. This is the first report of a human disease phenotype related to genetic variation in SMAD6. Hum Mutat 33:720–727, 2012. © 2012 Wiley Periodicals, Inc.

BackgroundTetralogy of Fallot (TOF) is common in individuals with hemizygous deletions of chromosome 22q11.2 that remove the cardiac transcription factor TBX1.ObjectiveTo assess the contribution of common and rare TBX1 genetic variants to TOF.DesignRare TBX1 variants were sought by resequencing coding exons and splice-site boundaries. Common TBX1 variants were investigated by genotyping 20 haplotype-tagging SNPs capturing all the common variations present at the locus. Association analysis was performed using the program UNPHASED.PatientsTBX1 exons were sequenced in 93 patients with non-syndromic TOF. Single nucleotide polymorphism analysis was performed in 356 patients with TOF, their parents and healthy controls.ResultsThree novel variants not present in 1000 chromosomes from healthy ethnically matched controls were identified. One of these variants, an in-frame 57 base-pair deletion in the third exon which removed 19 evolutionarily conserved residues, decreased transcriptional activity by 40% in a dual luciferase assay (p=0.008). Protein expression studies demonstrated that this mutation affected TBX1 protein stability. After correction for multiple comparisons, no significant associations between common genetic variants and TOF susceptibility were found.ConclusionThis study demonstrates that rare TBX1 variants with functional consequences are present in a small proportion of non-syndromic TOF.