Hypophosphatasia is a rare inherited disorder that affects the way bones and teeth are formed. A genetic mutation prevents hard tissues in the body from mineralizing correctly, which means they are left brittle and malformed. The severity of the disorder can vary greatly, and some people only experience minor problems related to bone aches in adulthood. Serious cases can result in potentially fatal complications in early infancy and childhood. There is no clear cure for the disorder, but a combination of surgery, physical therapy, and medications can help many people with hypophosphatasia manage their conditions well and enjoy active lifestyles.
Bones and teeth gain their hardness through a process called mineralization that begins in the womb and continues throughout a person's life. An enzyme called alkaline phosphatase normally directs the mineralization process, allowing for calcium, phosphates, and other hard substances to be put to use in forming bones. People who suffer from hypophosphatasia do not produce enough functional alkaline phosphatase enzymes to facilitate normal mineralization. Milder forms of the condition have an autosomal dominant pattern of inheritance, which only requires one parent to carry a defective copy of the gene that codes for alkaline phosphatase production. Severe hypophosphatasia usually occurs when both parents are carriers of the mutated gene.
Hypophosphatasia that is present at birth is usually characterized by serious breathing and feeding difficulties and obvious skeletal defects. The chest may be caved in and the arms and legs are often much shorter than normal. In less serious cases, hypophosphatasia symptoms may not appear until later in childhood. A child may lose his or her baby teeth at an early age, have bowed legs and wrists, and frequent respiratory problems due to fragile chest bones. Symptoms that do not develop until adulthood are typically milder and may include higher susceptibility to foot and leg fractures, early loss of adult teeth, and arthritis in multiple body joints.
Treatment for hypophosphatasia depends on the severity of symptoms. Infants who are born with life-threatening complications typically need to be placed on ventilators and other supportive machines in hopes of preventing lung and heart failure. Older patients often need to take medications that help their bones absorb more calcium and other vital minerals. Surgical procedures may be considered to reinforce bones with metal rods and screws. In addition, physical therapy sessions can help adult patients build muscle strength and reduce the chances of suffering bone fractures.