A case report of -related hyperphosphatasia with impaired intellectual development syndrome in a Chinese family and literature review.

Recently, mutations have been identified in six genes (, , , , and ) encoding proteins in the Glycosyl phosphatidylinositol(GPI)-anchor-synthesis pathway in individuals with hyperphosphatasia with impaired intellectual development syndrome(HPMRS). Reports involving the rare pathogenic gene, post-GPI attachment to proteins 2 () are quite limited. In this study, we reported two patients with variants related neurodevelopmental disorders from Asian population. The proband, onset of epileptic spasms at 5 months, concurrently with global developmental dalay, facial malformation and elevated alkaline phosphatase. His younger sister, onset of epileptic spasms at 2 months, having similar clinical features as the proband. Their phenotypes are consistent with related diseases. The two missense variants [c.686C>T (p.Ala229Val) and c.677C>T (p.Thr226Ile)] in gene found in this family were segregation with the disease, while c.677C>T (p.Thr226Ile) was a novel variant. All the two patients showed a positive response to ACTH treatment and high-dose pyridoxine. In summary, this study contributes to expanding the pathogenic variant spectrum of related HPMRS, and provides new insights into the treatment.