Two GNPTAB Variations Caused Mucolipidosis II Alpha/Beta in a Chinese Family

Introduction: Mucolipidosis II alpha/beta (ML II) is an autosomal recessive disorder with craniofacial dysmorphism and bone deformities. The variants in GNPTAB are associated with ML II. Materials and Methods: A female pediatric patient presented with bone deformities, mental and motor developmental abnormalities and craniofacial dysmorphism. We performed clinical whole-exome sequencing (WES) and verified the variants via qPCR, gap-PCR and Sanger sequencing. Results: Clinical WES identified a point variant c.1090C > T (p.R364*) and a copy number variation (CNV) in GNPTAB. Compared with normal control, GNPTAB expression was reduced in blood of the proband. Using Gap-PCR and Sanger sequencing, we identified the break point of CNV (NC_000012.11:g.102136912_102142973del), and successfully performed prenatal diagnosis for the proband's mother. Conclusion: To our knowledge, this is the first report of this novel CNV associated with ML II. Our findings expand the genotypes related to ML II and contribute to the gene diagnosis of ML II.