Kallmann's syndrome - beyond "migration"

Article Abstract:

Kallmann's syndrome involves the incomplete development of the sex organs and a lack of the sense of smell. It is caused by a deficiency of gonadotropin-releasing hormone (GnRH). GnRH is normally secreted by cells in the hypothalamus of the brain, but in Kallmann's syndrome patients, these cells are absent. In the developing embryo, these cells originate in the olfactory region of the brain - responsible for the sense of smell - and then migrate to the hypothalamus. The DNA sequence of the KALIG-1 gene associated with Kallmann's syndrome indicates that the protein it produces is similar to other proteins involved in cell migration. But it may instead direct the growth of nerve cells into the developing brain. In Kallmann's syndrome patients, these cells may have lost their way. An autopsy of a 19-week-old male fetus from a Kallmann's syndrome family found GnRH-producing cells still clustered in his olfactory region.

Editorial, Growth, Nervous system

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Mutations of the connexin43 gap-junction gene in patients with heart malformations and defects of laterality

Article Abstract:

Mutations in the gene for connexin43 may cause some types of severe congenital heart defects. Connexin43 is a protein that forms channels between heart muscle cells which allows ions to pass between the cells. Researchers used the polymerase chain reaction and DNA sequencing to detect mutations of the connexin43 gene in 25 healthy people and 30 children with congenital heart disease. Six of the children with a heart defect called visceroatrial heterotaxia had a mutation in the gene and five had one particular mutation. Several also had other mutations. Heart cell cultures that contained the defective connexin43 protein were still able to form channels, but they could not transfer as much dye between the cells as cells that had the normal protein. They were also unresponsive to an enzyme called protein kinase, which normally controls the activity of channels created by the normal connexin43 protein.

Genetic aspects, Congenital heart defects, Congenital heart disease in children, Cell junctions

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Genetic defects of intracellular-membrane transport

Article Abstract:

Several genetic diseases have been linked to defects in the transport of proteins inside cells. They include Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, Griscelli's syndrome, Usher's syndrome type 1B, inclusion-cell disease, combined factor V and VIII deficiency, choroideremia, and X-linked non-specific mental retardation.

Health aspects, Biological transport, Active, Active biological transport

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