Genetic imprinting suggested by maternal heterodisomy in nondeletion Prader-Willi syndrome

Article Abstract:

Prader-Willi syndrome (PWS) is a hereditary form of obesity that involves unusual eating behavior; patients may binge frequently unless food is made unavailable. PWS may also involve mild mental retardation and growth retardation. Genetics researchers have uncovered evidence that helps to explain the way PWS may be inherited. Two families in which a child had PWS were studied. It appears that each child inherited double chromosomes from his mother rather than one from his mother and one from his father, as is normal. Chromosomes are the structures that contain the DNA, or genetic code, found in all cells. Humans have 23 pairs of chromosomes, and the specific chromosome involved in PWS was chromosome 15. One critical region of chromosome 15 was apparently transferred from mother to child twice. This phenomenon is called maternal heterodisomy, and may play a part in the etiology of PWS. The scientists theorize that normal development of the child depends on receipt of genetic information from both parents, and the lack of the father's contribution to this region of chromosome 15 may cause PWS. There is also a possibility that absence of the mother's contribution instead could cause a different illness known as Angelman syndrome. The transmission of only one parent's chromosome, known as genetic imprinting, could be involved in other genetic diseases such as Huntington's chorea and certain childhood cancers.

Research, Causes of, Heredity, Human, Human heredity, Prader-Willi syndrome, Human chromosome abnormalities

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Abnormal splicing of the leptin receptor in diabetic mice

Article Abstract:

The leptin receptor variant, Ob-Rb, undergoes abnormal splicing in the C57BL/Ks mice containing a mutant diabetic (db) gene. Abnormal splicing of the protein results in a loss of the cytoplasmic area which is involved in signal transduction. Ob-Rb is expressed in high concentrations in the hypothalamus. Signal transduction by a hypothalamic leptin receptor is probably essential for the leptin's activity in decreasing weight. The leptin receptor, which maps the position of the db gene in mouse genome, has about six alternatively spliced forms.

Physiological aspects, Observations, Proteins, Mutation (Biology), Mutation, Cell receptors, Hypothalamus, Mice as laboratory animals, House mouse

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Obesity in the new millennium

Article Abstract:

It has been possible to identify several genes that cause human and animal obesity. This provides strong evidence that obesity is not merely the result of personal failing. Obesity genes generally encode the molecular elements of the physiological system that controls body weight.

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