Expansion of the CGG repeat in fragile X in the FRM1 gene depends on the sex of the offspring

Journal Article · Fri Dec 01 04:00:00 EST 1995 · American Journal of Human Genetics

OSTI ID:186212

Loesch, D Z; Huggins, R ^[1]; Petrovic, V ^[2]

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1. La Trobe Univ., Bundoora, Victoria (Australia)
2. 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, Journal Name: American Journal of Human Genetics Journal Issue: 6 Vol. 57; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
DNA
DNA REPLICATION
GENES
GENETIC MAPPING
GENETICS
HUMAN X CHROMOSOME
MENTAL DISORDERS
METHYLATION
MUTATIONS
NUCLEOTIDES
PATIENTS
PROGENY
SEX DEPENDENCE
SIZE