Por el contrario los portadores de la PM usualmente presentan un Coeficiente Intelectual normal con leves o sin caracteristicas fisicas; sin embargo, el 20% de las mujeres portadoras de la PM presenta FXPOI
o FXTAS, y el 40% de los hombres portadores desarrolla FXTAS.
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.
Importantly, although FMR1 CGG repeats are implicated in both FX syndrome (FXS) and FXPOI, the mechanisms of disease are very different.
Two predominant disease models have been proposed to explain FXPOI.
Conclusive diagnosis of FXPOI requires confirmation of increased serum FSH concentrations and detection of 55-200 CGG repeats in the 5' UTR of FMR1.
Diagnosis of FXPOI requires detection of an expanded CGG repeat region in the premutation range, by PCR, sequencing, or Southern blot.
1] Nonstandard abbreviations: FM, full mutation; PM, premutation; FXS, fragile X syndrome; FXPOI
, fragile X-associated primary ovarian insufficiency; FXTAS, fragile X-associated tremor/ataxia syndrome; MCA, melting curve analysis; msTP-PCR, methylation-specific triplet-primed PCR; GZ, gray zone; TT, threshold temperature; NL, normal; uTP-PCR, unmethylated allele triplet-primed PCR; mTP-PCR, methylated allele triplet-primed PCR.