Deletion of steroid 5-alpha-reductase 2 gene in male pseudohermaphroditism
Article Abstract:
Pseudohermaphroditism is the failure of the development of normal male genitalia in individuals who have the normal 46, XY set of chromosomes. Some clinicians reserve the term for individuals with indeterminate genitalia, while others extend its use to include individuals with female external genitalia. The failure of the external male genitalia to develop is apparently a result of some defect in the metabolism of the male sex hormones. The enzyme 5-alpha-reductase plays a key role in the metabolism of sex hormones; it converts the male hormone testosterone into dihydrotestosterone. This conversion is essential not only for the prenatal development of male characteristics, but also for the growth of tissues stimulated by the male hormones. Researchers studying the human 5-alpha-reductase gene failed to find a mutation in the gene in pseudohermaphroditic patients with a demonstrable deficiency in the enzyme itself. Further research uncovered the existence of a second gene for this enzyme. There are several instances in which the tissues of the body can make two closely related versions of the same enzyme. Such closely related enzymes are called isozymes, and in the present case have been termed 5-alpha-reductase 1 and 5-alpha-reductase 2. When the 5-alpha-reductase 2 genes were studied in two related pseudohermaphroditic males, DNA deletions in this gene were found. The results establish that there are two different isozymes for 5-alpha-reductase and that the second reductase appears to be the more important in genital tissues. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1991
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Mending and malignancy
Article Abstract:
The sensation of heartburn is caused by acid reflux from the stomach into oesophagus. Persistent heartburn may indicate lethal cancer, oesophageal adenocarcinoma. The increased cancer risk is associated with other types of chronic tissue injury caused by toxins, chronic infection or other pathogens.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2004
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Transplanted bone marrow regenerates liver by cell fusion
Article Abstract:
Results from several experimental systems suggest that cells from one tissue type can form other tissue types after transplantation. This could be due to the presence of multipotential or several types of adult stem cells in donor tissues, or alternatively, to fusion of and recipient cells.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2003
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