Fragile X Syndrome Essay

Submitted By Rodrinoe001
Words: 617
Pages: 3

Fragile X Syndrome, or FXS, is a genetic condition where changes appear on one of the X chromosomes, causing many developmental problems including learning disabilities. Because both males and females have one X chromosome, both can pass on the mutated gene to their children. Males and females are both capable of inheriting FXS, but because males only have one X chromosome, a single fragile X is likely to affect them more severely. As to females having two X chromosomes, one altered X will not affect them as much because they still have an alternate chromosome. Even though your parents might not have FXS, it is still possible for you to obtain the syndrome through inheritance of past family members even if there are no signs of Fragile X syndrome in the family.
Not everyone will display similar symptoms of FXS. In general symptoms can be divided into two categories, behavioral problems and physical signs. Behavioral problems would include delay in crawling, walking, speaking and language development, a tendency to avoid eye contact, constant clapping or biting of the hands, and impulsive behavior. Physical signs would include a slender face, large forehead or ears, soft skin, flexible joints, and flat feet. Many of these symptoms can be present at birth.
FXS is cause by a repetition on the FMR1 gene. The mutation is most likely on a fragile part of the X chromosome. The more repeats, the likelier to have more problems. Mutation at that site is found in 1 out of about every 2000 males and 1 out of about every 259 females. Incidence of the disorder itself is about 1 in every 3600 males and 1 in 4000–6000 females. Although this accounts for over 98% of cases, FXS can also occur as a result of point mutations affecting FMR1.
Fragile X Mental Retardation 1, or FMR1, is a gene that produces protein needed for your brain to grow properly. A defect in this gene will cause your body to make less protein, or none at all. In unaffected individuals, the FMR1 gene contains 5-44 repeats of the CGG codon, most commonly 29 or 30 repeats. Between 45 and 54 repeats is considered a "grey zone", with a premutation allele generally considered to be between 50 and 200 repeats in length. Individuals with fragile X syndrome have a full mutation of the FMR1 allele, with over 200 repeats of the CGG codon. In these individuals with a repeat expansion greater than 200, there is…