Prenatal Diagnosis of Severe Perinatal (Lethal) Hypophosphatasia

HPP is a clinically heterogeneous disease and classified into at least six forms according to severity and age of onset: perinatal (lethal), perinatal (benign), infantile (MIM [Mendelian Inheritance in Man] # 241500), childhood (MIM# 241510), adult (MIM# 146300), and odontohypophosphatasia (Mornet, 2008) (Table 1). All forms of HPP display reduced activity of unfractionated serum ALP and the presence of either one or two pathologic mutations in the liver/bone/kidney alkaline phosphatase gene (ALPL, MIM# 171760), the gene encoding ALP, the tissue-nonspecific isozyme (TNSALP). There is no curative treatment for HPP to date.