Biopsychosocial issues of a patient with mucolipidosis type II

Mucolipidosis type II (ML II; MIM: 252500) is an extremely rare lysosomal storage disease caused by homozygous or compound heterozygous mutation in the GNPTAB gene over chromosome 12q23.2. Only eight patients have been diagnosed with this disease in Taiwan. It is also called I-cell disease because inclusion bodies can be found in cultures of fibroblasts from these patients. A defect in the enzyme N-acetylglucosaminyl-1-phosphotransferase leads to progressive generalized accumulation of mucopolysaccharides and lipids. In addition to physical disability, symptom-related psychosocial problems at different developmental milestones should be addressed. The only case found in eastern Taiwan was in a 7-year, 11month-old boy, who presented with progressive limitation of movement in the small joints since the age of 3 years. The boy had a short stature [body height: 107.7 cm ( 3.7 SD), body weight: 19.5 kg (10e25%)], coarse facial features, puffy eyelids, a flat nasal bridge, gingival hypertrophy, malocclusion, a protruding abdomen, claw hands, and limited range of motion of multiple joints, but no umbilical hernia; his liver and spleen could not be palpated (Fig. 1). A panel of enzyme assays revealed marked increases in most lysosomal enzymes such as beta-glucuronidase of 1333.33 nmol substrate/h/mL (normal range: 5.6e101.5 nmol substrate/h/mL)