ISL1 loss-of-function mutation contributes to congenital heart defects

Area of Science:

• Genetics
• Cardiology
• Developmental Biology

Background:

• Congenital heart defect (CHD) is a common birth defect with significant health impacts.
• Genetic factors are crucial in CHD development, but the specific genetic basis remains largely unknown.
• The ISL1 gene is a potential candidate involved in heart development.

Purpose of the Study:

• To identify pathogenic mutations in the ISL1 gene associated with congenital heart defects (CHD).
• To investigate the functional consequences of identified ISL1 mutations on gene activity.

Main Methods:

• Sequencing of ISL1 coding exons and splicing boundaries in 210 CHD patients and 256 controls.
• Pedigree analysis to confirm co-segregation of mutations with CHD.
• Dual-luciferase reporter assay to assess the functional impact of the ISL1 mutation.

Main Results:

• A novel heterozygous ISL1 nonsense mutation (c.409G>T or p.E137X) was identified in a patient with patent ductus arteriosus and ventricular septal defect.
• The mutation segregated with CHD in the family in an autosomal dominant pattern with complete penetrance and was absent in controls.
• Functional assays showed the mutant ISL1 protein could not transactivate the MEF2C promoter, alone or with TBX20.

Conclusions:

• This study provides the first evidence implicating ISL1 loss-of-function mutations in human CHD.
• The findings offer new insights into the molecular mechanisms underlying CHD.
• This discovery has potential implications for genetic counseling and personalized treatment of CHD patients.