Dilated cardiomyopathy in mucolipidosis type 2

Mucolipidosis II and III are lysosomal storage diseases caused by pathogenetic mutations in GNPTAB and GNPTG genes which cause an impaired activity of the lysosomal hydrolase N-acetylglucosamine- 1-phosphotransferase, a key enzyme in the synthesis of the mannose-6-phosphate targeting signals on lysosomal enzymes. Patients with MLII alpha/beta present coarse facial features, cessation of statural growth, important skeletal manifestations, impaired neuromotor development and cardiorespiratory involvement. All children appear to have cardiac involvement, but severe dilated cardiomyopathy is uncommon. In this report we describe the case of an 11-month-old girl who is affected by a MLII. Analysis of the GNPTAB gene identified at a heterozygous level the previously described gene variants c. 2693delA p(Lys898Serfs*13) and c. 2956C>T p(Arg986Cys). Her main clinical features were coarse face with gingival hypertrophy, dysostosis multiplex, recurrent respiratory infection and an early onset of dilated cardiomyopathy, an uncommon feature for MLII. To our knowledge, dilated cardiomyopathy has been previously described in literature in only two cases of MLII and in one patient affected by MLIII.