Albright's Hereditary Osteodystrophy

Definition

Definition of Albright's Hereditary Osteodystrophy
Albright’s hereditary osteodystrophy is form of osteodystrophy, otherwise known as Pseudohypoparathyroidism type 1a.

Symptoms

Symptoms of Albright's Hereditary Osteodystrophy
AHO with pseudohypoparathyroidism (PHP) In addition to AHO, in PHP the body is unable to respond to various hormones. One such hormone is parathyroid hormone (PTH), which maintains levels of calcium and phosphate in the blood. In PHP, parathyroid hormone is produced in normal or increased amounts by the parathyroid glands and released into the blood. However, the body is resistant to its effects causing hypocalcaemia (low calcium levels), and hyperphosphatemia (high phosphate levels). Signs of hypocalcaemia include tingling in the fingers, muscle cramps, possible seizures (fits) and, in the longer term, cataracts. Hypocalcaemia typically begins in mid-childhood. Individuals with PHP are often resistant to thyroid stimulating hormone (TSH), which makes the thyroid gland produce thyroid hormone. The effects of lack of thyroid hormone are a tendency to gain weight easily and to feel the cold, dry skin and hair, and a lack of energy.

Causes

Causes of Albright's Hereditary Osteodystrophy
Mutations in a gene called GNAS1 carried on chromosome 20 cause these conditions. Pseudohypoparathyroidism can also occur on its own without AHO and is caused by a different type of genetic change affecting the same GNAS1 gene.

Diagnosis

Diagnosis of Albright's Hereditary Osteodystrophy
The physical features of AHO are diagnosed by examination usually by an experienced clinical geneticist or endocrinologist. It may be necessary to do X-rays particularly of the hands, feet and spine to confirm the diagnosis. Many of the features of AHO are not specific to this condition, that is, they can have many different causes of which genetic changes in the GNAS1 gene are only one. Chromosome testing may be requested to look for some other conditions that can resemble AHO.

PHP is diagnosed by testing of the blood and urine for biochemical changes associated with resistance to PTH and TSH, such as low calcium, raised phosphate, high PTH, low thyroxine and high TSH levels. In people in whom the diagnosis is strongly suspected, specific testing for genetic changes (mutations) in the GNAS1 gene is available, which picks up an abnormality in about 70 per cent of affected people.

Treatment

Treatment of Albright's Hereditary Osteodystrophy
Fortunately, the low calcium levels experienced with this condition can be treated with vitamin D, and low thyroid levels can be treated with thyroxine.

Prognosis

Prognosis of Albright's Hereditary Osteodystrophy
Consult with your doctor.

Prevention

Prevention of Albright's Hereditary Osteodystrophy
Consult with your doctor.