GCMB

Hypoparathyroidism, Familial Isolated

Clinical Characteristics
Ocular Features: 

Lens opacities may be present.

Systemic Features: 

The major signs and symptoms result from hypocalcemia. Neuromuscular irritability and various paresthesias may be present.  Some patients have  laryngeal spasm and latent tetany with grand mal seizures.  Alopecia, abnormal dentition and coarse brittle hair may be present.  Cognitive deficits and personality disorders are often a feature.  Brain imaging may show calcification of the basal ganglia.  Serum calcium levels are usually low while phosphorus levels are elevated.   Vitamin D precursor levels are usually low or low normal.

Genetics

Familial hypoparathyroidism may be due to mutations in the PTH gene (11p15.3) (either autosomal dominant or recessive inheritance) or in the GCMB gene (6p24.2) (autosomal dominant inheritance pattern).

There is also an X-linked form of hypoparathyroidism (307700) in which parathryroid tissue may be congenitally absent.

A family has been reported in which hypoparathryroidism was associated with lymphedema (247410) and progressive renal failure.  Ptosis, telecanthus, hypertrichosis, restrictive lung disease, and mitral valve prolapse may also be part of the disorder.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

Normalization of calcium and phosphorus levels is a priority and this may result in some clearing of the lens opacities.  Cataract surgery may be indicated in selected individuals.

References
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