Qualitative assessment of FMR1 (CGG)n triplet repeat status in normal, intermediate, premutation
, full mutation, and mosaic carriers in both sexes: implications for fragile X syndrome carrier and newborn screening.
and intermediate alleles in the ID cohort
Many laboratories incorrectly identified samples with 42 repeats as gray-zone or premutation
Repeat CGG sequences are categorized into four classes based on repeat length: normal (<45 repeats); intermediate (45-54 repeats); premutation
(55-200 repeats); and full mutation (>200 repeats).
3% of the general female population may be premutation
carriers; the prevalence of males with premutations
is approximately half that.
Would parents be inclined to display confidence-eroding bias toward a child who harbors a premutation
, which may carry little risk of developmental disability?
AGG Genotyping Reclassifies Expansion Risk for Equivalently Sized Intermediate and Premutation
Fragile X Alleles: Outcomes of a Multicenter Study of 469 Mother-Child Transmissions" (Andrew Hadd, Asuragen; Sarah Nolin, NYS-IBR; Elizabeth Berry-Kravis, Rush; Flora Tassone, UC-Davis; Stephanie Sherman, Emory, Abstract No.
Because her FSH concentration was increased in the setting of hypoestrogenism, PCR testing of the FMR1 5' UTR identified the patient as having an FMR1 premutation
allele with 82 CGG repeats and the second allele containing 51 CGG repeats (reference intervals: normal, 5-44 repeats; intermediate, 45-54; premutation
, 55-200; full mutation, >200 repeats), resulting in a conclusive diagnosis of FXPOI.
Press Conference on Major Announcements Related to Premutation
Women who carry a premutation
in one of their two copies of the FMR1 gene have a 13%-26% risk of developing POF.
7) On the other hand, clinical interpretation depends on the clinical context: For example, an FMR1 gene premutation
is interpreted differently if the patient is a child with developmental delay, a pregnant woman, a woman having trouble becoming pregnant, or an elderly man with ataxia.
are unstable and can expand in size when passed from mother to child If the premutation
expands to the size of a full mutation, the FMR-1 gene "turns off" and does not work properly.