Jacobs Syndrome

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  • Topic: Y chromosome, Aneuploidy, Syndromes
  • Pages : 2 (607 words )
  • Download(s) : 135
  • Published : November 8, 2009
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Jacobs Syndrome
Jacobs Syndrome, also known as XYY Syndrome, is a rare genetic disorder which affects males due to an extra Y chromosome. Males with this syndrome are sometimes called super males. Klinefelter's syndrome with an extra X-chromosome (47,XXY) and Turner's syndrome with lack of X-chromosome material (45,X) have been named after the physicians who first described the syndromes in 1942 and 1937. When Sandberg and co-wokers in 1961 found the chromosome constitution 47,XYY, the name became XYY males in accordance with triple-X women who have the chromosome constitution 47,XXX as first described by Jacobs and Strong in 1959. Sometimes the additional Y chromosome is present in only some of the cells of the body, but not all. This is referred to as a mosaic form of XYY syndrome. There is no known inheritance pattern except that only males get it. In very rare instances, the syndrome has been passed from father to son, but in most cases heredity cannot be established. XYY syndrome is a chromosomal condition which occurs only in males and is found with a frequency of one in a thousand. Thus, in Denmark with a population of five million, there are approximately three thousand XYY males. The effect of having an extra Y chromosome in some or all cells varies between individuals. Some males with XYY syndrome show very few symptoms. The majority are never diagnosed while others may be more severely affected. It is not possible, therefore, to offer a precise prediction of the symptoms before or even immediately after the birth of each XYY boy. Males with Jacob’s syndrome are tall, thin, have acne, and speech problems, as well as reading problems. In some cases, XYY males show learning difficulties, with slightly lowered intelligence scores for the group compared with XY males. They may have delayed speech development and have difficulties in communication. Boys with an extra Y chromosome seem to be at higher risk of having problems at school....
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