fragile X syndrome

noun
variants: or less commonly fragile X

Definition of fragile X syndrome

: an X-linked inherited disorder that is characterized especially by moderate to severe intellectual and developmental disabilities, an elongated face and prominent forehead, chin, and ears, and by large testes in males, and that often has limited or no effect in heterozygous females … most children with fragile X syndrome have other characteristic traits, including anxiety, hyperactivity, and a number of behaviors that are often seen in autism.— Mark Cohen The defective gene responsible for fragile X syndrome is carried on one leg of the X chromosome, the chromosome that helps determine the sex of a child.— Elaine T. Cicora Female carriers of fragile X syndrome as a group exhibit wide variation in degree of phenotypic involvement. Some heterozygotes are cognitively unaffected, others have learning disabilities, and approximately one third have significant mental impairment and an IQ score of less than 85.— Annette K. Taylor et al.

First Known Use of fragile X syndrome

1979, in the meaning defined above

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The first known use of fragile X syndrome was in 1979

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fragile X syndrome

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Cite this Entry

“Fragile X syndrome.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fragile%20X%20syndrome. Accessed 29 Nov. 2021.

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More Definitions for fragile X syndrome

fragile X syndrome

noun
\ -ˈeks- How to pronounce fragile X syndrome (audio) \
variants: also fragile X

Medical Definition of fragile X syndrome

: an X-linked inherited disorder that is caused by repeats of a trinucleotide sequence on the X chromosome which are abnormal in number and degree of methylation, that is characterized especially by moderate to severe intellectual and developmental disabilities, an elongated face and prominent forehead, chin, and ears, and by enlarged testes in males, and that often has limited or no effect in heterozygous females … most children with fragile X syndrome have other characteristic traits, including anxiety, hyperactivity, and a number of behaviors that are often seen in autism.— Mark Cohen Female carriers of fragile X syndrome as a group exhibit wide variation in degree of phenotypic involvement. Some heterozygotes are cognitively unaffected, others have learning disabilities, and approximately one third have significant mental impairment and an IQ score of less than 85.— Annette K. Taylor et al.

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