| monosomy | <genetics> Situation in a normally diploid cell or organism in which one or more of the homologous chromosome pairs is represented by only one chromosome of the pair. For example: sex determination in grasshoppers depends on the fact that females are XX and males XO, that is, males have only one sex chromosome and are monosomic for the X chromosome. (18 Nov 1997) |
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| monosomy x | A rare genetic disorder (1 in 3,000 births) in women that is characterised by the absence of an X chromosome. This disorder inhibits normal sexual development and causes infertility. Features include webbing of the neck, short stature, retarded development of secondary sex characteristics, absence of menses, coarctation of the aorta, low hairline, eye abnormalities (drooping eyelids) and skeletal deformities. Treatment include oestrogen supplementation at puberty. Growth hormone replacement may be necessary in some cases. Cardiac surgery may be necessary to correct coarctation of the aorta. (27 Sep 1997) |