Background Mucolipidosis II α/β (ML II) is an autosomal recessive disease associated with the abnormality of lysosomal enzyme trafficking. Case presentation We present an unusual patient with: (a) marked skeletal anomalies with secondary hyperparathyroidism; (b) serum intact parathyroid hormone level normalized by 7 weeks but abnormally elevated serum alkaline phosphate persisted; and (c) two mutations identified in the GNPTAB gene. One mutation, c.3503_3504delTC, is the most common mutation in ML II. However, the second mutation, c.2896delA, is a rare mutation for which clinical presentation has not been described previously.
Keywords: I-cell disease; ML II; mucolipidosis II; secondary hyperparathyroidism.