Purpose: Fragile X CGG repeat alleles often contain one or more AGG interruptions that influence allele stability and risk of a full mutation transmission from
Nolin Fragile X full mutation expansions are inhibited by one or more AGG interruptions in premutation carriers GeninMed
ing the risk of having a child with fragile X syndrome The presence had no AGG interruptions in the expanded premutation allele, 69 (26 ) had one
gim
person is at risk of having a child with a fragile X disorder are more likely to expand when the premutation is passed from a female carrier to her child
F Invitae RH result FragileX
Modification of Expansion Risk Elizabeth Premutation “carriers” - risk for FXTAS/FXPOI >1:100-1:250 Full mutation fragile X syndrome - FXS >1:4000
asuragen fmr interrptions
Fragile X carriers and risk of expansion Fragile X syndrome occurs in individuals with greater than 200 CGG repeats The risk of expansion in premutation
rep v
Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) **Risk of expansion from premutation to full mutation also depends on AGG repeat interruptions.
150–250 premutation alleles in females in the general popula- of fragile X however
The Fragile X syndrome is the most common cause of inherited mental retardation. For a female premuta- tion carrier the risk of having a child with a full
Fragile X syndrome a cause of mental retardation and autism
64 Women with alleles in this range are considered to be at risk for having affected children.65–67 The smallest FMR1 premutation allele reported to expand to a
Offspring of women who are premutation carriers are at risk to have fragile X syndrome. Expan- sion of the repeat region to more than 200 CGG trinucleotide
Expansion of the fragile X CGG repeat in females with premutations or intermediate alleles. Amer- ican Journal of Human Genetics 72
The risk for expansion of an intermediate allele to a premutation (greater than 55. CGG repeats) may be related to the absence of AGG interruptions which
premutation. Premutations are likely to show instability and further expansion in future generations with a risk of expansion to a full mutation. Prenatal
Sep 11 2014 are also at risk for premutation-associated disorders such as fragile X–associated tremor/ataxia syndrome (OMIM 300623).
FX-Premutation-Emory-12.13.15.pdf