We describe an 8-day-old baby girl presenting a fatal infantile form of hypertrophic obstructive cardiomyopathy, associated with an A8296G mutation in the mitochondrial tRNA(Lys) gene. She was born from a healthy unrelated couple, and was the first infant of dizygotic twins. Soon after birth, she was noted to have tachypnea and generalized hypotonia. She had high levels of lactate and pyruvate, and was diagnosed as having hypertrophic cardiomyopathy using echocardiography. She died by cardiac failure. Mitochondrial DNA analysis was performed by sequencing after PCR-subcloning methods, and the percentage of mutation was measured using PCR-RFLP methods. In various tissues obtained at autopsy, analysis showed a heteroplasmic population of A8296G mutation in the mitochondrial tRNA(Lys) gene in all the tissues examined. Maternal inheritance was demonstrated in the family members. Our data demonstrated that an A8296G mutation in the mitochondrial tRNA(Lys) gene showed clinical heterogeneity from a milder form previously reported as mitochondrial diabetes mellitus, to a more severe form as hypertrophic obstructive cardiomyopathy, according to the spatial distribution of this mutation. Hum Mutat 15:382, 2000.
Copyright 2000 Wiley-Liss, Inc.