Bone disease cracks genetics
Article Abstract:
A report is presented from a recent meeting in Italy concerning osteogenesis imperfecta (OI), 'brittle bone' disease, a genetic disorder involving abnormal calcification. The high incidence of this disorder seems at variance with its disadvantageous nature. It appears that the mutation rate is high because of the structure of the collagen molecule, the substance that forms bone matrix, which becomes calcified in formation of mature bone. The molecule contains a large number of residues of glycine, an amino acid. In OI, other amino acids are substituted for glycine, which is called 'axial glycine' because of its position in the three-dimensional collagen molecule. Fifty-three different substitutions, usually, by cysteine, another amino acid, were reported at the meeting. The genetic bases for these aberrations have been partly elucidated. The disorder itself takes many forms, ranging from one that is lethal in infancy to one that is mild, with a slightly increased tendency for bones to fracture. The role played by different axial glycine mutants, substitutions at different places in the molecule, of these forms is discussed. Collagen genes also are prone to mutation as a result of the many coding and non-coding regions the DNA. An additional source of variation in OI is the apparent presence of different cell types, such as somatic and germ-line mosaics, which contain both mutated and normal forms of collagen DNA. People with somatic mosaicism display features of mild OI; in one case, the patient appeared to be affected on one side only. Thus, there is still much to be explored regarding the nature of mutation in this disease and its importance at all stages of development. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1990
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Lifetime of plasma cells in the bone marrow
Article Abstract:
Immunization studies show that human bone marrow plasma cells secrete antibodies for twelve months or more following immunization. Murine bone-marrow plasma cells research has established that sustained levels of detected antibody are released by the same plasma cells and not from new ones that have been synthesized through the process of differentiation.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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