Abstract
BACKGROUND AND OBJECTIVES: Mucolipidosis II (MLII) is characterized by severe global developmental delay, coarse facial features, skeletal deformities, and other systemic involvement. It is caused by a deficiency in N-acetylglucosamine-1 phosphotransferase. DESIGN AND SETTINGS: This is a case series study conducted at King Abdulaziz Medical City in Riyadh, Saudi Arabia, between 2008-2012. PATIENTS AND METHODS: We described three unrelated Saudi children who presented with neonatal hyperparathyroidism, microcephaly, craniosynostosis, coarse facial features, cardiac involvement, and skeletal deformities. RESULTS: The MLII diagnosis was confirmed by assaying enzyme activities in fibroblasts, which showed a severe reduction in hydrolyzed substrates compared to controls, and by identifying a pathogenic homozygous GNPTAB gene mutation. One of the children died at 2 months of age due to severe pulmonary hypertension, and the other two children were still alive at 12 months and 18 months of age, respectively. Both surviving children had severe global developmental delay at 2 months of age. CONCLUSION: Clinicians should investigate any child presenting with neonatal hyperparathyroidism, craniosynostosis, skeletal deformities, and coarse facial features for MLII.