Adult hypophosphatasia caused by ALPL mutation: one pedigree study

An adult patient with hypophosphatasia caused by compound heterozygous mutations in alkaline phosphatase, liver /bone /kidney(ALPL)gene was investigated through comprehensively reviewing the medical history and clinical records of the proband and her family members in order to better understand the disease. The proband and her older sister had mild decreased serum alkaline phosphatase level accompanied with frequently nontraumatic fractures at limbs and all the teeth fell off at the age of 20 and 7, respectively. Both of them carried a missense mutation c. 407G>A(p.Arg136His)in exon 5 and a deletion mutation c. 1318_1320delAAC(p.Asn440del)in exon 12 simultaneously. Other four family members were p. Arg136His mutation carriers and two members were p. Asn440del mutation carriers. We found that p. Asn440del mutation was associated with the oral disorders. In this family, compound heterozygous manifested more serious symptoms, while heterozygous showed relatively mild symptoms. In addition, it is necessary to differentiate it from primary osteoporosis and other diseases of disturbed bone mineralization. (Chin J Endocrinol Metab, 2017, 33: 585-589) Key words: Adult hypophosphatasia; ALPL gene; Compound heterozygous mutations