Cardiac involvement in nonketotic hyperglycinemia.

Nonketotic hyperglycinemia is an autosomal recessive disorder of glycine metabolism characterized by the accumulation of glycine in the serum and cerebrospinal fluid with elevated cerebrospinal fluid to serum glycine ratio. The disease primarily affects the central nervous system, and has not been previously associated with myocardial involvement. In this article, the authors report an infant with nonketotic hyperglycinemia, who was found to have progressive left ventricular hypertrophy and dysfunction. His older sibling, who had a similar neurologic presentation, died of dilated cardiomyopathy as stated by the parents. The authors speculate that glycine may have a role in the development of cardiac dysfunction. The incidence of cardiac involvement may be under-diagnosed. They suggest the need for a cardiac evaluation in confirmed cases of nonketotic hyperglycinemia.