Dilated cardiomyopathy and sensorineural hearing loss: a heritable syndrome that maps to 6q23-24

Dilated cardiomyopathy (DCM) and sensorineural hearing loss (SNHL) are prevalent disorders that occur alone or as components of complex multisystem syndromes. Multiple genetic loci have been identified that, when mutated, cause DCM or SNHL. However, the isolated coinheritance of these phenotypes has not been previously recognized.

Clinical evaluations of 2 kindreds demonstrated autosomal-dominant transmission and age-related penetrance of both SNHL and DCM in the absence of other disorders. Moderate-to-severe hearing loss was evident by late adolescence, whereas ventricular dysfunction produced progressive congestive heart failure after the fourth decade. DNA samples from the larger kindred (29 individuals) were used to perform a genome-wide linkage study. Polymorphic loci on chromosome 6q23 to 24 were coinherited with the disease (maximum logarithm of odds score, 4.88 at locus D6S2411). The disease locus must lie within a 2.8 cM interval between loci D6S975 and D6S292, a location that overlaps an SNHL disease locus (DFNA10). However, DFNA10 does not cause cardiomyopathy. The epicardin gene, which encodes a transcription factor expressed in the myocardium and cochlea, was assessed as a candidate gene by nucleotide sequence analysis; no mutations were identified.

A syndrome of juvenile-onset SNHL and adult-onset DCM is caused by a mutation at 6q23 to 24 (locus designated CMD1J). Recognition of this cardioauditory disorder allows for the identification of young adults at risk for serious heart disease, thereby enabling early intervention. Definition of the molecular cause of this syndrome may provide new information about important cell physiology common to both the ear and heart.