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It's not secret agent Fragile X: The coding of Fragile X.

© Laura Ruth

Fragile X is not a secret agent working for the government. Fragile X is the most common heritable form of mental retardation. Down's syndrome is the number one disease which causes mental retardation. 1 - 3 % of the general population is mentally retarded. Fragile X approximately accounts for 0.3% of the mentally retarded female population and 0.2% of the mentally retarded male population. A person who is mentally retarded can be deficient in motor, language, and self-help skills. Symptoms of mental retardation are a lack of curiosity, decreased learning ability, and an IQ of less than 70. People with Fragile X mental retardation may have a long narrow face with a prominent jaw, forehead, and ears. Males can have enlarged testicles.

An insertion of extra nucleotide bases in the Fragile X Mental Retardation 1 (FMR1) gene on the X chromosome, identified in 1991, cause Fragile X mental retardation. The name 'Fragile X' came from the observation in the microscope of broken or weak looking X chromosomes from some mentally retarded people. DNA and chromosome analysis is available to identify the FMR1 gene and the number of extra nucleotide bases inserted in the disease gene. The number of extra inserted bases in the FMR1 gene determines if a person is a carrier of Fragile X disease or affected with Fragile X disease. Interestingly, Shohat and colleagues in Israel reported that 62% of mothers who carry an abnormal FMR1 gene with a medium number of inserted nucleotide bases passed the gene to offspring. In comparison, mothers with larger number of inserted nucleotide bases did not have an increased rate of passing the gene to offspring.

References

Drasinover, V., Ehrlich, S., Magal, N., Taub, E., Libman, V., Shohat, T., Halpern, GJ, Shohat, M., 'Increased transmission of intermediate alleles of the FMR1 gene compared with normal alleles among female heterozygotes,' Am. J. Med. Genetics, 93(2): 155-7, 2000.

URL's:

Yahoo! Health: Fragile X Syndrome http://health.yahoo.com/health/Diseases_...

The National Fragile X Foundation http://www.nfxf.org/

Fragile X Syndrome: FAQ's http://TheArc.org/faqs/fragqa.html

Fragile X Syndrome http://www.familyvillage.wisc.edu/lib_fr...

Fragile X Association of Southern California Photograph of Kids http://www.fraxsocal.org/

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