"Reduction" of CGG trinucleotide expansion from mother to offspring in seven fragile-X families.
DZ Loesch, V Petrovic, DI Francis, R Oertel, H Slater
Clinical Genetics | Published : 1997
Apparent reduction in the size of the CGG repeat is reported from seven fragile-X mothers to nine offspring in seven extended families. The overall frequency of the reduction amongst 121 fragile-X mother-fragile-X child transmissions was 7.4%, compared with an 18% reduction in fragile-X father-fragile-X daughter transmissions, but ascertainment bias may account for some underestimation of the frequency of reductions, especially between mothers and their offspring. In one mother-son transmission, a premutation present in the son (with a full mutation present in the mother) was unmethylated. This may be the result of either demethylation with reduction, or undetected mosaicism in the mother. T..View full abstract