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).