Desmin mutation responsible for idiopathic dilated cardiomyopathy

Area of Science:

• Genetics and Molecular Biology
• Cardiology
• Biochemistry

Background:

• Familial dilated cardiomyopathy (FDCM) accounts for 20% of idiopathic dilated cardiomyopathy cases, leading to heart failure and transplantation needs.
• Previous research mapped six autosomal dominant FDCM loci, but causative genes remained elusive until actin was identified.
• Desmin, a muscle-specific intermediate filament, is implicated in cardiac growth and development, making it a candidate gene for FDCM.

Purpose of the Study:

• To investigate whether desmin gene defects cause familial dilated cardiomyopathy (FDCM).
• To identify the specific genetic mutation responsible for FDCM in affected families.

Main Methods:

• Clinical evaluation and DNA analysis of 44 probands with FDCM.
• Echocardiography used to diagnose dilated cardiomyopathy based on ventricular dimensions and ejection fraction.
• Sequencing of desmin gene exons after polymerase chain reaction amplification.

Main Results:

• A novel missense desmin mutation, Ile451Met, was identified in a 4-generation family with FDCM.
• This mutation cosegregated with FDCM and did not present with clinically evident skeletal muscle abnormalities.
• The Ile451Met mutation was absent in 460 unrelated healthy individuals, confirming its association with FDCM.

Conclusions:

• The novel desmin mutation Ile451Met is the genetic cause of idiopathic dilated cardiomyopathy in the studied family.
• This is the first mutation found in the desmin tail domain, suggesting its critical role in cardiac function.
• The restricted cardiac phenotype associated with this mutation implies the desmin tail is crucial for heart tissue function.