Hyperphosphatasia with Mental Retardation Syndrome Due to a Novel Mutation in PGAP3 .

Hyperphosphatasia with mental retardation syndrome is a heterogeneous genetic condition. Two siblings aged 5 years and 3 years were evaluated for global development delay and facial dysmorphism. A novel missense variant, c.851A>G (p.H284R, NM_033419.3), in PGAP3 was identified using whole-exome sequencing. Assays for elevated alkaline phosphatase and exome sequencing can be useful for the diagnosis of hyperphosphatasia with mental retardation syndrome.