Identification of de novo mutations and rare variants in hypoplastic left heart syndrome

Area of Science:

• Genetics
• Developmental Biology
• Cardiology

Background:

• Hypoplastic left heart syndrome (HLHS) is a severe congenital heart malformation with an unknown specific genetic cause.
• Existing research has implicated multiple genetic loci but lacks a definitive gene or pathway.
• HLHS affects the development of the left heart and aorta, often leading to critical illness in newborns.

Purpose of the Study:

• To elucidate the genetic basis of isolated HLHS using an integrated genomic approach.
• To identify novel genetic mutations and variants associated with HLHS.
• To explore the role of specific genes and pathways in HLHS pathogenesis.

Main Methods:

• Analysis of 53 patients with isolated HLHS.
• DNA sequencing of candidate genes (NKX2-5, NOTCH1, HAND1, FOXC2, FOXL1).
• Genome-wide screening using high-resolution array comparative genomic hybridization.

Main Results:

• Identification of two novel de novo mutations in the NOTCH1 gene.
• Discovery of rare inherited gene variants in NOTCH1, FOXC2, and FOXL1 in 23 patients.
• Detection of rare copy-number variants in 33 patients, with some variants coexisting within individuals.

Conclusions:

• Findings strengthen the role of the NOTCH pathway in cardiac valve development, suggesting HLHS is partly a 'valve' disease.
• This is the first report of de novo mutations linked to isolated HLHS.
• The coexistence of multiple rare variants may indicate a cumulative effect in some HLHS cases.