Fragile X syndrome

Fragile X syndrome is an inherited neurodevelopmental disorder caused by deficient FMRP, usually after expansion and silencing of the FMR1 gene. It commonly affects learning, behavior, and development.

FMR1: FMR1 is a gene on the X chromosome that encodes fragile X messenger ribonucleoprotein, or FMRP. Its expanded CGG repeat can trigger the gene silencing that causes the syndrome.
X-linked inheritance: X-linked inheritance describes the transmission of traits caused by variants in genes on the X chromosome. FMR1 is X-linked, so inheritance and expression differ by sex.
Fragile X testing: Fragile X testing measures the FMR1 CGG repeat and may assess methylation to identify expansions and gene silencing. It can confirm the diagnosis and identify premutation carriers in a family.
Fragile X-associated tremor/ataxia syndrome: Fragile X-associated tremor/ataxia syndrome is a late-onset neurological disorder associated with an FMR1 premutation. It is a distinct premutation-associated condition, rather than the childhood syndrome caused by FMRP deficiency.
James Purdon Martin: James Purdon Martin was a British neurologist who co-described a familial form of intellectual disability later associated with fragile X. His 1943 report with Julia Bell provided an early clinical account of the condition.
FMRP: FMRP is an RNA-binding protein that regulates the production of many proteins in neurons. Its absence is the central molecular defect in Fragile X syndrome.
CGG repeat expansion: A CGG repeat expansion is an increase in the number of consecutive CGG units in a gene. The size of the FMR1 expansion helps distinguish premutation from full mutation.
Genetic counseling: Genetic counseling helps people understand inherited conditions, testing choices, and reproductive or family implications. FMR1 repeat instability makes relatives' carrier status relevant to family planning.
Autism spectrum disorder: Autism spectrum disorder is a neurodevelopmental condition involving social-communication differences and restricted or repetitive behaviors. Autistic features can occur in Fragile X, but the conditions are not interchangeable.
Julia Bell: Julia Bell was a British geneticist whose work included documenting inherited disorders and human pedigrees. Her collaboration with Martin described the family pattern now recognized as Fragile X syndrome.

Linked from 5 pages