Expansion of the CGG repeat in fragile X in the FRM1 gene depends on the sex of the offspring
- La Trobe Univ., Bundoora, Victoria (Australia)
- Royal Children`s Hospital, Melbourne (Australia); and others
Analysis of 139 mother-to-offspring transmissions of fragile X CGG triplet repeats revealed that the repeat expansion is enhanced in mother-to-son transmissions compared with mother-to-daughter transmissions. Evidence has been based on analysis of mother-offspring differences in the size of repeat (in kb), as well as on comparisons between proportions of male and female offspring with premutations, and full mutations, inherited from mothers carrying a premutation. Mean difference in the repeat size from mother-son transmissions was 1.45 kb, compared with mother-daughter transmissions of 0.76 kb. The difference is due primarily to a greater proportion of male than female offspring with full mutation from the premutation mothers and also to a higher frequency of reduction in repeat size from mothers to daughters than from mothers to sons. Our findings suggest the possibility of an interaction of the normal X homologue in a female zygote with the FMR1 sequence on the fragile X during replication to account for the lower level of expansion in mother-to-daughter transmissions relative to mother-to-son transmissions. 27 refs., 3 figs., 2 tabs.
- OSTI ID:
- 186212
- Journal Information:
- American Journal of Human Genetics, Vol. 57, Issue 6; Other Information: PBD: Dec 1995
- Country of Publication:
- United States
- Language:
- English
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