[Molecular cloning of liver/bone/kidney-type alkaline phosphatase complementary and genomic DNA: analyses of its deficiency, infantile hypophosphatasia].

Alkaline phosphatase is an enzyme present in nearly all living organisms. The liver/bone/kidney-type isozyme (ALPL) is expressed in the liver, bone, kidney and in most other tissues. We have isolated the ALPL cDNA and its gene and indicated that the gene is divided into two leader exons (exon 1B and 1L) and 11 coding exons and the liver- and bone-specific transcriptions are regulated by their own promoters. The defect of ALPL results in infantile hypophosphatasia, a disorder characterized by defective bone mineralization and subnormal activity of circulating alkaline phosphatase. Prenatal diagnoses of the disease were successfully carried out. Mutation analysis of the family member is in progress.