Fragile X Syndrome

Introduction Fragile X syndrome is the most common driveway of inherited intellectual deliberation, seen in about one in 1,cc males and one in 2,500 females. Males with breakable X syndrome usually put up mental retardation and often exhibit characteristic forcible features and behavior [Hagerman and Silverman, 1991; warren and Nelson, 1994]. Affected females exhibit a similar, merely usually slight severe phenotype. The diagnosis of tenuous X syndrome was originally found on the expression of a pteroylmonoglutamic acid-sensitive fragile site at Xq27.3 (FRAXA) induced in cell assimilation under conditions of folate deprivation. Cytogenetic analysis of metaphase spreads demonstrates the front stamp out of the fragile site in less than 60% of cells in most affected individuals. The cytogenetic test has constrainations, especially in testing for carrier status, and it exhibits a high degree of variant between individuals and laboratories. Also, interpretation of the cy togenetic test for fragile X syndrome is complicated by the presence of other fragile sites in the same region of the X chromosome (FRAXD, FRAXE, and FRAXF). In 1991, the fragile X gene (FMR1) was characterized and found to contain a tandemly recalled trinucleotide grade (COG) near its 5 end. The mutation responsible for fragile X syndrome involves working out of this repeat segment.

The number of CGG repeats in the FMR1 genes of the normal population varies from six to approximately 50. There ar ii main categories of mutation, premutations of approximately 50 to 200 repeats and full mutations of more than than approximately 200 repeats. There is no clea! r boundary between the pep pill limit of normal and the lower limit of the premutation range. For this reason, alleles with approximately 45-55 copies of the repeat are said to be in the grey zone. slightly alleles in this size range are unstable and put out from generation to generation, while others are stably inherited. If you want to stick by a full essay, order it on our website: BestEssayCheap.com

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