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

Article Title:

Identification of a novel mutation disrupting the DNA binding activity of GCM2 in autosomal recessive familial isolated hypoparathyroidism

Baumber L, Tufarelli C, Patel S, King P, Johnson CA, Maher ER, Trembath RC. Identification of a novel mutation disrupting the DNA binding activity of GCM2 in autosomal recessive familial isolated hypoparathyroidism. J Med Genet. 2005 May;42(5):443-8.

PubMed ID:

13863676

Mutation of the signal peptide-encoding region of the preproparathyroid hormone gene in familial isolated hypoparathyroidism

Arnold A, Horst SA, Gardella TJ, Baba H, Levine MA, Kronenberg HM. Mutation of the signal peptide-encoding region of the preproparathyroid hormone gene in familial isolated hypoparathyroidism. J Clin Invest. 1990 Oct;86(4):1084-7.

PubMed ID:

2212001

Familial isolated hypoparathyroidism: a molecular genetic analysis of 8 families with 23 affected persons

Ahn TG, Antonarakis SE, Kronenberg HM, Igarashi T, Levine MA. Familial isolated hypoparathyroidism: a molecular genetic analysis of 8 families with 23 affected persons. Medicine (Baltimore). 1986 Mar;65(2):73-81.

PubMed ID:

3005800

Autosomal or X-linked recessive syndrome of congenital lymphedema, hypoparathyroidism, nephropathy, prolapsing mitral valve, and brachytelephalangy

Dahlberg PJ, Borer WZ, Newcomer KL, Yutuc WR. Dahlberg PJ, Borer WZ, Newcomer KL, Yutuc WR. Autosomal or X-linked recessive syndrome of congenital lymphedema, hypoparathyroidism, nephropathy, prolapsing mitral valve, and brachytelephalangy. Am J Med Genet. 1983 Sep;16(1):99-104.

PubMed ID:

6638075

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