The disorder affects mineralization — the process through which calcium and phosphorus are deposited in developing bones and teeth. HPP causes defective mineralization, which means that instead of teeth and bones that are strong and rigid, a person’s bones are soft and prone to fracture and deformity. A person may also experience premature tooth loss. HPP affects infants, children, and adults. It can be severe and life-threatening, especially before birth and just after it, but many experience milder forms of the disease. Rickets, a bone disorder that affects children, produces many of the same symptoms, but it’s usually not inherited, and is caused by a lack of calcium and vitamin D. (There is an inherited form of rickets, but it is very rare.) There are six main types of HPP. They are:
Benign prenatal HPPLethal perinatal HPPInfantile HPPChildhood HPPAdult HPPOdontohypophosphatasia
In benign prenatal HPP, an unborn infant may present with skeletal defects that will resolve into a less severe form of HPP. Lethal perinatal HPP results in death, either in the womb or by stillbirth. Odontohypophosphatasia, which only affects the teeth, is the mildest form of the condition.
Short stature with bowed legs or knock kneesDecreased mobilitySkeletal malformationsBone and joint painEnlarged wrist or ankle jointsAbnormal skull shapeLosing baby teeth earlier than usual
Softening of the bonesFrequent fractures of the foot and thigh bonesPremature loss of teethJoint pain and inflammation
Odontohypophosphatasia is characterized by the premature loss of baby teeth in childhood, or premature loss of teeth in adulthood. With this form of HPP, there are no symptoms that affect or involve the bones.
Prognosis of Hypophosphatasia
Other treatments target specific symptoms and complications. These treatments include:
Nonsteroidal anti-inflammatory drugs (NSAIDs) to treat bone and joint painVitamin B6 to help to control seizures in severely affected infantsRegular dental care beginning early onPhysical and occupational therapy
Surgery may also be recommended. Adults suffering from repeated fractures may undergo a procedure called rodding, in which an orthopedic surgeon places a metal rod through the center opening of a bone to make it stronger and more stable. Children may be given orthotic braces to encourage stability, and in-sole orthotics may be used by both adults and children.
Prevention of Hypophosphatasia
Hypophosphatasia cannot be prevented, but treatments such as the ones outlined above are available to help manage the symptoms.
Respiratory problems, including a predisposition to pneumoniaHypercalcemia, or high levels of calcium in the bloodIncreased intracranial pressure caused by craniosynostosis (the premature closure of one or more of the joints that connect the bones of a baby’s skull)Nephrocalcinosis, a disorder that occurs when too much calcium is deposited in the kidneys, is another possible complication.
Complications in adults with HPP include chronic pain of the bones, joints, and muscles. They may also lose their secondary (adult) teeth prematurely.
Osteogenesis Imperfecta (OI) This is a group of rare disorders affecting connective tissues and characterized by brittle and fragile bones that fracture easily.Rickets As mentioned earlier, this bone disorder can be caused by genetic inheritance or by calcium and vitamin D deficiencies, a lack of sun exposure, or maternal malabsorption of those nutrients during pregnancy.Campomelic Dysplasia This rare genetic disorder affects the development of the skeleton, reproductive system, and the face. It develops before birth and children born with the disorder rarely survive past infancy, according to MedlinePlus.Achondrogenesis A group of severe disorders, present from birth, that affect the development of cartilage and bone. Most infants with achondrogenesis have severely underdeveloped lungs, and most die before or shortly after birth, notes the Genetic and Rare Diseases Information Center.
This charitable nonprofit organization was created to provide support for the families of children afflicted with conditions and diseases that affect a child’s growth, including hypophosphatasia. The organization can help parents of newly diagnosed children connect with other parents whose children are living with the disease. Soft Bones Soft Bones exists to provide information and support to people living with hypophosphatasia (HPP) and their caregivers. The nonprofit’s Resource Library is a go-to source for recent news articles, helpful fact sheets, podcasts, and webinars. Their online community form, HPP and Me, can connect you with other patients, families, and caregivers. With additional reporting by Carlene Bauer.
