Fragile X syndrome: molecular analysis reveals a new mechanism of mutation in human genetic diseases.
The fragile X syndrome belongs to the most common genetic diseases and has a prevalence of one in every 2000 children. The syndrome is named after the fragile site in q27.3 on the X chromosome. The molecular cloning of the DNA containing the fragile site has resulted in the identification of a heritable unstable DNA sequence revealing a new mechanism of mutation in human genetic disorders. This DNA sequence significantly facilitates the diagnosis and provides a rapid method for carrier detection and prenatal diagnosis. The unstable element is located within a candidate gene, FMR1. The FMR1 protein is not made in fragile X patients and nothing is known about its function. We will have to await studies on this protein to be able to understand the variable phenotype of this disease.
Poustka
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Deutsches Krebsforschungszentrum, Heidelberg, Germany.
D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation; D010641:Phenotype; D014960:X Chromosome