Manic depression: a new gene defect.Manic depression Noun 1. manic depression - a mental disorder characterized by episodes of mania and depression bipolar disorder, manic depressive illness, manic-depressive psychosis : A new gene defect There have been a spate of recentstudies concerned with the genetic basis of manic depression, and the latest effort indicates that either of at least two genetic defects may predispose pre·dis·pose v. To make susceptible, as to a disease. individuals to this severe disorder. Scientists who studied five large familiesin Jerusalem report in the March 19 NATURE that cases of manic depression or related mood disorders The mood or affective disorders are mental disorders that primarily affect mood and interfere with the activities of daily living. Usually it includes major depressive disorder (MDD) and bipolar disorder (also called Manic Depressive Psychosis). were linked to genetic markers near one tip of the X chromosome X chromosome One of the two sex chromosomes (the other is Y) that determine a person's gender. Normal males have both an X and a Y chromosome, and normal females have two X chromosomes. . Researchers recently linked manic depression among three Amish families in Pennsylvania to a defect on chromosome 11 (SN: 2/28/87, p.132), although the same defect did not show up in two other studies of non-Amish families. The critical gene in both the Israeli and Amish families has not been identified. The possibility that manic depressionis influenced by a gene on the X chromosome has been suggested previously, since more women than men are affected and family studies have documented that both fathers and sons seldom have the disorder. The 23rd and final pair of human chromosomes consists of two X chromosomes for females and one X and one Y chromosome Y chromosome, n a sex chromosome that in humans and many other species is present only in the male, appearing singly in the normal male. It is carried as a sex determinant by one half of the male gametes. None of the female gametes contain a Y chromosome. for males. The Y chromosome is inherited from the father. Miron Baron of Columbia University inNew York City and his colleagues at Yale University School of Medicine and Hebrew University-Hadassah Medical School in Jerusalem isolated genetic material from 161 adults, 47 of whom had manic depression or related disorders, in five Jewish families. DNA-cutting enzymes were used to locate two genetic markers at one tip of the X chromosome linked to color blindness color blindness, visual defect resulting in the inability to distinguish colors. About 8% of men and 0.5% of women experience some difficulty in color perception. and a chemical deficiency that causes anemia. The genetic mutations occurred overwhelmingly among subjects with the psychiatric diagnoses. Further analysis confirmed this patternamong the four families of Mediterranean and Asian origin, but not among the one family of Eastern European descent. X-linked inheritance of manic depression may be more pronounced among Jews and other groups in the former regions, suggest the researchers. The findings do not indicate that manicdepression is more common in those populations, note the scientists. Nor is there evidence that color blindness or the genetically caused anemia are accompanied by manic depression in the population at large. The investigators estimate, however,that perhaps one-third of all manic depressives carry the X-linked gene X-linked gene n. A gene located on an X-chromosome. X-linked gene A gene carried on the X chromosome, one of the two sex chromosomes. Mentioned in: Mucopolysaccharidoses . |
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