There are more than 400 mutant alleles identified for the ALPL gene (the ALPL mutation database http://alplmutationdatabase.hypophosphatasie.com), and their genotype/phenotype correlations are not well understood.(15, 16) The inheritance pattern of perinatal and infantile HPP is often autosomal recessive, with most patients being compound heterozygotes for pathogenic ALPL mutations that result in almost null alkaline phosphatase (ALP) activity, but some are homozygous for recessive alleles and most adult and odonto‐HPP patients harbor a single dominant‐negative ALPL allele.(17, 18). This evidence concerns the gene ALPL and hypophosphatasia.