Fragile X Syndrome

Introduction Fragile X syndrome is the most common fare of inherited intellectual deliberation, seen in somewhat one in 1,cc males and one in 2,500 females. Males with breakable X syndrome usually wipe out mental retardation and often exhibit characteristic bodily features and behavior [Hagerman and Silverman, 1991; warren and Nelson, 1994]. Affected females exhibit a similar, still usually slight severe phenotype. The diagnosis of soft X syndrome was originally found on the expression of a pteroylmonoglutamic acid-sensitive fragile site at Xq27.3 (FRAXA) induced in cell horticulture under conditions of folate deprivation. Cytogenetic analysis of metaphase spreads demonstrates the front expiry 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 variation between individuals and laboratories. Also, interpretation of the cytogene tic 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 accepted trinucleotide place (COG) near its 5 end. The mutation responsible for fragile X syndrome involves refinement of this repeat segment. The number of CGG repeats in the FMR1 genes of the normal population varies from hexad 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 clear boundary between the focal ratio 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. some alleles in this size range are unstable and expound from generation to generation, while others are stably inherited. If you wa! nt to spawn a full essay, order it on our website: BestEssayCheap.com

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