Fragile-X syndrome: unique genetics of the heritable unstable element.
Year: 1992
Type: article
Abstract: The fragile site at Xq27.3 is an unstable microsatellite repeat, p(CCG)n. In fragile-X syndrome pedigrees, this sequence exhibits variable amplification, the length of which correlates with fragile-site expression. There is a direct relationship between increased p(CCG)n copy number and propensity for instability: individuals having large amplifications exhibit somatic variation due to increased instability. The instability of the p(CCG)n repeat, when transmitted through affected pedigrees, explains the unusual segregation patterns of fragile-X phenotype, referred to as the Sherman paradox. All individuals of fragile-X genotype were found (where testing was possible) to have a parent with amplified p(CCG)n repeat, indicating that few, if any, cases of fragile-X syndrome are not familial.
Source: Europe PMC (PubMed Central)
Institution: Women's and Children's Hospital
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W1941644192