Skeletal System: Hypophosphatasia

Disease: Hypophosphatasia


Common Name: Hypophosphatasia, but comes in one of the 5 forms: perinatal, infantile, childhood, adult, and odontohypophosphatasia.

Age of Onset: the disease is inherited; but can occur anytime throughout life.

Duration: Lifetime

Common in both male and female.

Causes: A mutation in the gene that codes for tissue-nonspecific alkaline phosphatase is believed to be the cause of hypophosphatasia. The gene has been named ALPL . The ALPL gene is located at band Perinatal and infantile hypophosphatasia have an autosomal recessive mode of inheritance. Both autosomal recessive and autosomal dominant patterns of inheritance have been demonstrated for the childhood, adult, and odontohypophosphatasia forms.

Symptoms: They vary and can appear anywhere from birth to adulthood. The most severe type occurs before birth or ealry infancy. It weakens and softens the bones, which caused skeletal abnormalities (similar to rickets). Infants who are affected are born with short limbs, soft skull bones, and an abnormally shaped chest. Poor feeding, failure to gain weight, hypercalcemia (high levels of calcium in the blood) which leads to kindey problems and uncontrolled vomiting, and respiratory problems occur in infancy. These complications are life-threatening in some cases. The cases that appear in childhood and adulthood are less severe than those who have it as infants. Lossing baby (primary) teeth early is the first sign of children with this disease. The children may be short with bowed legs or knocked knees, abnormal skull shape, and enlarged ankle and wrist joints. Adult forms are characterized by a softening of bones (osteomalcia). Reccurent fractures of thigh and foot bones can have chronic pain, and affected adults may lose thier adult (secondary) teeth early. The adults are at a greater risk of for joint pain and inflammation.

Prognosis: The earlier the diagnosis is made the more severe the skeletal appears. Cases detected in the womb or with severe deformity at birth almost always have a lethal outcome within days or weeks. When the diagnosis is made before the individual is six months old, some infants have a downhill and fatal course. Others survive and may even do well. When they are diagnosed during childhood, premature loss of teeth (less than five years old) is the most common symptom. Adults may have recurrent fractures in their feet and thigh bones.

Treatment Options: Treatment with Vitamin D and its breakdown products has not been successful in Hypophosphatasia and other forms of Vitamin-D resistant Rickets. Sustained oral phosphate supplements may be beneficial in some cases. Other treatment depends on the symtoms, like per scribing a drug to help with the pain. Genetic counseling is recommended for families of persons with Hypophosphatasia.




Source: http://www.magicfoundation.org/www/docs/175/