Contiguous Xp21 deletion involving Duchenne muscular dystrophy and McLeod neuroacanthocytosis syndrome results in rapidly progressive and fatal cardiomyopathy.

Dilated cardiomyopathy is an expected manifestation and common cause of death in patients with Duchenne muscular dystrophy. We present an unusually rapid progression of cardiomyopathy in a boy with Duchenne muscular dystrophy. Expanded genetic testing revealed a contiguous Xp21 deletion involving dystrophin and XK genes, responsible for Duchenne muscular dystrophy and McLeod neuroacanthocytosis syndrome, respectively, resulting in a more severe cardiac phenotype.