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Purpose:We aimed to determine the prevalence and phenotypic spectrum of NOTCH1 mutations in left-sided congenital heart disease (LS-CHD). LS-CHD includes aortic valve stenosis, a bicuspid aortic valve, coarctation of the aorta, and hypoplastic left heart syndrome.Methods:NOTCH1 was screened for mutations in 428 nonsyndromic probands with LS-CHD, and family histories were obtained for all. When a mutation was detected, relatives were also tested.Results:In 148/428 patients (35%), LS-CHD was familial. Fourteen mutations (3%; 5 RNA splicing mutations, 8 truncating mutations, 1 whole-gene deletion) were detected, 11 in familial disease (11/148 (7%)) and 3 in sporadic disease (3/280 (1%)). Forty-nine additional mutation carriers were identified among the 14 families, of whom 12 (25%) were asymptomatic. Most of these mutation carriers had LS-CHD, but 9 (18%) had right-sided congenital heart disease (RS-CHD) or conotruncal heart disease (CTD). Thoracic aortic aneurysms (TAAs) occurred in 6 mutation carriers (probands included 6/63 (10%)).Conclusion:Pathogenic mutations in NOTCH1 were identified in 7% of familial LS-CHD and in 1% of sporadic LS-CHD. The penetrance is high; a cardiovascular malformation was found in 75% of NOTCH1 mutation carriers. The phenotypic spectrum includes LS-CHD, RS-CHD, CTD, and TAA. Testing NOTCH1 for an early diagnosis in LS-CHD/RS-CHD/CTD/TAA is warranted.Genet Med 18 9, 914–923.

A newborn girl presented with asphyxia, joint contractures and diminished spontaneous movements. Echocardiography showed hypoplastic left heart. Spinal muscular atrophy type I (SMA I) was diagnosed by detecting a homozygous deletion in the survival motor neuron 1 gene (SMN1). In the first trimester of a subsequent pregnancy, SMA I, hypoplastic left heart, and contractures were identified again. Congenital heart defects (CHD) have now been reported in 20 patients with SMA I, including three previously reported siblings and our two siblings, leading us to hypothesize that SMA I/CHD represents a unique phenotype of SMA I rather than a coincidental association. The homozygous SMN1 deletion may play a role in the development of CHD when it occurs in the presence of mutations or polymorphisms in other genes important for cardiac development. © 2008 Wiley‐Liss, Inc.