[Mucolipidosis type II (I-cell disease) with unusually severe heart involvement].

Mucolipidosis II (I-cell disease), an autosomal recessive inborn error of mucolipid metabolism with defective transport of lysosomal enzymes is described in a young infant. Besides the typical findings as a result of the "lysosomopathy", this case presented an unusual and distinct cardiac involvement: a cardiomyopathy with dilatation of the left ventricle and signs of an endocardfibroelastosis.