Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
Hypophosphatasia is a rare inherited metabolic disorder of decreased tissue nonspecific alkaline phosphatase (TNSALP) and defective bone mineralization. Both autosomal recessive and autosomal dominant variants of the disease exist.
The disease comes in one of five forms, perinatal, infantile, childhood, adult, and odontohypophosphatasia. Perinatal hypophosphatasia is invariably lethal while infantile hypophosphatasia has a roughly 50% mortality rate with symptoms appearing within the first 6th months after birth. The other forms are generally non-lethal.
Common symptoms include bone malformations and higher chance of bone fracture. Both the adult form and odontohypophosphatasial form are marked by premature tooth loss.
There is no known cure for hypophosphatasia. However, there have been some claims that choline may have positive health benefits for those with the disease that take it as a dietary supplement.
Chorionic villus sampling (CVS) is used during the first trimester. A monoclonal antibody assay for TNSALP activity is available, as are DNA testing methods. By the second trimester, many of the skeletal abnormalities can be noted on ultrasound Currently, protocol involves the use of CVS followed by serial ultrasonography. [1]
The perinatal form is considered lethal, whereas the infantile form has a mortality rate of 50%. Individuals with the other forms can reach adulthood, although often with increased morbidity. Patients with the childhood form often have rachitic deformities, and those with the adult type have increased morbidity from poorly healing stress fractures. All patients experience premature loss of dentition. A mutation in the gene that codes for tissue-nonspecific alkaline phosphatase is believed to be the cause of hypophosphatasia. The gene has been given the designation 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. [1]
The signs and symptoms of hypophosphatasia vary widely and can appear anywhere from before birth to adulthood The most severe forms of the disorder tend to occur before birth and in early infancy. Hypophosphatasia weakens and softens the bones, causing skeletal abnormalities similar to another childhood bone disorder called rickets. Affected infants are born with short limbs, an abnormally shaped chest, and soft skull bones. Additional complications in infancy include poor feeding and a failure to gain weight, respiratory problems, and high levels of calcium in the blood (hypercalcemia), which can lead to recurrent vomiting and kidney problems. These complications are life-threatening in some cases. The forms of hypophosphatasia that appear in childhood or adulthood are typically less severe than those that appear in infancy. Early loss of primary (baby) teeth is one of the first signs of the condition in children. Affected children may have short stature with bowed legs or knock knees, enlarged wrist and ankle joints, and an abnormal skull shape. Adult forms of hypophosphatasia are characterized by a softening of the bones known as osteomalacia. In adults, recurrent fractures in the foot and thigh bones can lead to chronic pain. Affected adults may lose their secondary (adult) teeth prematurely and are at increased risk for joint pain and inflammation. [2]
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