News tagged with fragile x syndrome

Related topics: brain · autism

A nucleotide change could initiate fragile X syndrome

Researchers reveal how the alteration of a single nucleotide—the basic building block of DNA—could initiate fragile X syndrome, the most common inherited form of intellectual disability. The study appears in The Journal ...

Sep 01, 2014
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Fragile X syndrome

Fragile X syndrome, or Martin-Bell syndrome, is a genetic syndrome which results in a spectrum of characteristic physical, intellectual, emotional and behavioural features which range from severe to mild in manifestation.

The syndrome is associated with the expansion of a single trinucleotide gene sequence (CGG) on the X chromosome, and results in a failure to express the FMR1 protein which is required for normal neural development. There are four generally accepted forms of Fragile X syndrome which relate to the length of the repeated CGG sequence; Normal (29-31 CGG repeats), Premutation (55-200 CGG repeats), Full Mutation (more than 200 CGG repeats), and Intermediate or Gray Zone Alleles (40 - 60 repeats).

Martin and Bell in 1943, described a pedigree of X-linked mental disability, without considering the macroorchidism (larger testicles). In 1969 Chris and Weesam first sighted an unusual "marker X chromosome" in association with mental disability. In 1970 Frederick Hecht coined the term "fragile site".

Renpenning's syndrome is not synonymous with the syndrome. In Renpenning's syndrome, there is no fragile site on the X chromosome. Renpenning's cases have short stature, moderate microcephaly, and neurological (brain) disorders.

Escalante's syndrome is synonymous with the fragile X syndrome. This term has been used in Brazil and other South American countries.

This text uses material from Wikipedia, licensed under CC BY-SA

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