A NOVEL MITOCHONDRIAL-DNA POINT MUTATION ASSOCIATED WITH MITOCHONDRIAL ENCEPHALOCARDIOMYOPATHY

A novel mitochondrial DNA (mtDNA) mutation at position nt 4320 in the tRNA(Ile) gene was associated with severe encephalopathy in a 7-month- old infant, who died of intractable hypertrophic cardiomyopathy. The m utation was present in heteroplasmic fashion (88%) in muscle and fulfi lls accepted criteria for pathogenicity. This is the fourth pathogenic mutation identified in this gene, which appears to be a ''hotspot'' f or deleterious mutations affecting the heart. This report adds to the evidence of genetic heterogeneity in hypertrophic cardiomyopathies. (C ) 1995 Academic Press, Inc.