title: Evidence of founder chromosomes in fragile X syndrome.
abstract: The mutation responsible for fragile X syndrome and myotonic dystrophy involves the amplification of a simple trinucleotide repeat sequence, which increases in successive generations of affected pedigrees accounting for increasing penetrance of both disorders. This common molecular basis suggests that the two diseases may share other genetic features, but whereas myotonic dystrophy exhibits a significant founder chromosome effect, fragile X syndrome apparently has a very high mutation frequency. By haplotype analysis of microsatellite markers which flank the fragile X unstable element, we have uncovered evidence of founder chromosomes of the fragile X 'mutation'. Disorders caused by heritable unstable elements may therefore exhibit common genetic properties including anticipation and founder chromosomes.
authors.affiliation: Department of Cytogenetics and Molecular Genetics, Adelaide Children's Hospital, North Adelaide, South Australia.
authors.forename: R I
authors.initials: RI
authors.lastname: Richards
authors.forename: K
authors.initials: K
authors.lastname: Holman
authors.forename: K
authors.initials: K
authors.lastname: Friend
authors.forename: E
authors.initials: E
authors.lastname: Kremer
authors.forename: D
authors.initials: D
authors.lastname: Hillen
authors.forename: A
authors.initials: A
authors.lastname: Staples
authors.forename: W T
authors.initials: WT
authors.lastname: Brown
authors.forename: P
authors.initials: P
authors.lastname: Goonewardena
authors.forename: J
authors.initials: J
authors.lastname: Tarleton
authors.forename: C
authors.initials: C
authors.lastname: Schwartz
mesh_terms: D001483:Base Sequence; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D011110:Polymorphism, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014960:X Chromosome