The aim of a new study published in the Journal of Medical Genetics was to elucidate the molecular mechanism in benign familial hyperphosphatasemia. Here, ALPI gene sequencing and in vitro protein expression analysis were conducted. A deletion-insertion variant in the C-terminal end of the ALPI gene was identified, the variant which causes the attenuation of the hydrophobicity in GPI-anchor signal of intestinal alkaline phosphatase (IAP). An in vitro GPI-cleaving assay exhibited that the membrane-bound IAP was greatly decreased, whereas the soluble IAP was increased, in the variant IAP. Hence, it was inferred that C-terminal variant in ALPI causes the benign familial hyperphosphatasemia of IAP by the attenuation of the membrane-binding capability.