A gene deleted in Kallmann's syndrome shares homology with neural cell adhesion and axonal path-finding molecules

Article Abstract:

Kallmann's syndrome is characterized by a variety of neurological disorders, anosmia (inability to smell), and imbalances caused by reduction in the size and function of the gonads as a result of reduced secretion of pituitary hormones. The anosmia is caused by the absence of the olfactory bulbs, which receive nerve signals from the olfactory nerve, and the tracts that then carry olfactory information into the brain. The gene that is defective in Kallmann's syndrome is located on the X chromosome, specifically Xp22.3. In many cases, the region of the chromosome containing the gene is simply deleted. This is one of the few genes on the X chromosome that is represented on the Y chromosome as well. Furthermore, this gene seems to be similar in a great many species, suggesting that it may serve an especially important role. Researchers have now used techniques of molecular biology to study this gene in detail. The gene is deleted in patients with Kallmann's disease; sequencing of the gene from health subjects reveals that it is similar to specific genes for molecules that are critical in brain development. These molecules are thought to play an important role in the contact between cells of the developing nervous system; it is only by establishing proper contacts that cells of the nervous system and nerve fibers find their proper locations and establish correct interconnections. The similarity between these molecules and the gene involved in Kallmann's disease strongly suggests that the latter gene may be performing similar functions. Kallmann's disease appears to result from a defect in the normal migration of cells in the olfactory system and a defect in the normal migration of cells in the hypothalamus, which controls the release of the pituitary hormones. Several neurological deficits and syndromes are though to result from abnormalities in neuronal migration; Kallmann's syndrome may be the first condition in which the actual molecular basis of the abnormality has been identified. (Consumer Summary produced by Reliance Medical Information, Inc.)

Genetic aspects, Growth, Cell adhesion molecules, Nervous system

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GL13 zinc-finger gene interrupted by translocations in Greig syndrome families

Article Abstract:

A report is presented concerning genetic abnormalities in Greig cephalopolysyndactyly syndrome (GCPS), a condition in which affected individuals have fused toes and fingers as well as facial abnormalities. A hybrid cell line was constructed from human and mouse cells to investigate the short arm of chromosome 7, which has been identified as abnormal in people with GCPS. Base deletions in the GL13 gene have been implicated; these studies probed the points in the gene where breaks are likely to occur, causing genetic translocations (regions where genetic material is transferred to another chromosome or another portion of the same chromosome). Three breakpoints were identified along the GL13 gene. The results indicate that a mutation that affects a GL13 allele (one of two or more genes with specific inheritable characteristics) could cause GCPS syndrome, possibly affecting the gene's role in regulating the development of the limbs, head and face. (Consumer Summary produced by Reliance Medical Information, Inc.)

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