perinatal lethal hypophosphatasia (Monarch Disease Ontology identifier MONDO_0016605) is a rare, genetic form of hypophosphatasia (HPP) characterized by markedly impaired bone mineralization in utero due to reduced activity of serum alkaline phosphatase (ALP) and causing stillbirth or respiratory failure within days of birth. Also known as: HPPN, perinatal lethal Rathburn disease, perinatal lethal phosphoethanolaminuria.