Odontohypophosphatasia

Odontohypophosphatasia is the mildest clinical form of hypophosphatasia (HPP), a rare inherited metabolic disorder caused by mutations in the ALPL gene, which encodes tissue-nonspecific alkaline phosphatase (TNSALP). Unlike more severe forms of hypophosphatasia that affect the skeleton and multiple organ systems, odontohypophosphatasia is characterized by dental manifestations with little or no skeletal involvement. The condition primarily affects the teeth and supporting dental structures. The hallmark feature of odontohypophosphatasia is premature loss of deciduous (baby) teeth, typically with intact roots, due to deficient cementum formation and reduced alveolar bone mineralization. Affected individuals may lose their primary teeth before the age of five, often beginning with the incisors. In some cases, premature loss of permanent teeth can also occur. Patients typically have reduced serum alkaline phosphatase activity and may show elevated levels of natural substrates of TNSALP, including phosphoethanolamine (PEA), inorganic pyrophosphate (PPi), and pyridoxal 5'-phosphate (PLP, vitamin B6) in blood or urine. Management of odontohypophosphatasia focuses primarily on dental care, including preventive dentistry, dental prosthetics, and close monitoring by dental professionals experienced with the condition. For patients with more significant disease burden, enzyme replacement therapy with asfotase alfa (Strensiq) has been approved for hypophosphatasia, though its use in the purely odonto form is not standard. Genetic counseling is recommended for affected families, as the condition can be inherited in either an autosomal dominant or autosomal recessive pattern depending on the specific ALPL mutation involved.

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