fragile-X syndrome

a major genetic disorder caused by a constriction near the end of the long arm of an X chromosome. The fragile-X syndrome is second only to Down's syndrome as a cause of mental retardation. Affected males have unusually high foreheads, unbalanced faces, large jaws, long protruding ears, and large testicles. They have an IQ below 50 and are prone to violent outbursts. Folic acid helps to control their behaviour. About one-third of the females with this mutation on one of their two X chromosomes are also mentally retarded. Screening for the characteristic chromosome can be done by amniocentesis or chorionic villus sampling.

Medical dictionary. 2011.

Look at other dictionaries:

  • Fragile X syndrome — Classification and external resources Location of FMR1 gene ICD 10 Q99.2 …   Wikipedia

  • fragile X syndrome — fragile X syndrome. См. синдром Мартина Белл. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Fragile X syndrome — One of the most common causes of inherited mental retardation and neuropsychiatric disease in human beings, affects as many as one in 2000 males and one in 4000 females. The syndrome is also known as FRAXA (the fragile X chromosome itself) and as …   Medical dictionary

  • fragile-X syndrome — ▪ chromosomal disorder       a chromosomal disorder associated with a fragile site on the end of the X chromosome. The major symptom of the syndrome is diminished mental ability, which may range from mild learning impairment to severe… …   Universalium

  • fragile-X syndrome — a major genetic disorder caused by a constriction near the end of the long arm of an X chromosome. The fragile X syndrome is second only to Down s syndrome as a cause of mental retardation. Affected males have unusually high foreheads, unbalanced …   The new mediacal dictionary

  • fragile x syndrome — noun also fragile x Usage: usually capitalized x Etymology: so called from a fragile (partially gapped) site at band Xq 27 of the X chromosome in those affected with the disorder : an X linked inherited disorder that is caused by a genetic… …   Useful english dictionary

  • fragile X syndrome — noun Date: 1979 an X linked inherited disorder that is characterized especially by moderate to severe mental retardation, by a long face and large ears, and by large testes in males and that often has limited or no effect in heterozygous females… …   New Collegiate Dictionary

  • fragile X syndrome — noun A particular, genetic syndrome, caused by the excessive repetition of a particular trinucleotide …   Wiktionary

  • fragile X syndrome — Most frequent cause of mental retardation. There is an expanded trinucleotide repeat, CGG, in the fra (X) gene …   Dictionary of molecular biology

  • fragile X syndrome — a widespread form of mental retardation caused by a faulty gene on the X chromosome. [1980 85] * * * …   Universalium

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