Reduced recombination in maternal meiosis coupled with non-disjunction at meiosis II leading to recurrent 47,XXX.
We determined the meiotic origin and the stage of non-disjunction of the extra X chromosomes in two sisters with 47,XXX chromosomal complements. Segregation of the X chromosomes in all family members was analyzed using X-linked short tandem repeat polymorphic (STRP) markers. Densitometric analysis of two STRP markers confirmed that both sisters had three copies of the X chromosome and the extra X chromosomes were maternally derived. Both sisters did not share the same maternal homologue suggesting that the recurrent trisomy is non-homologous X chromosome-specific. Haplotype analysis demonstrated a reduction to homozygosity for markers examined, covering most of the length of the X chromosomes in both sisters. These findings suggested that the extra X chromosomes have derived from meiotic II non-disjunction following a nullitransitional meiosis I (MI). A lack of recombination in the X chromosomes of both sisters suggests a possible maternal genetic defect leading to an erratic recombination at MI. This information may contribute to further understanding of mechanisms leading to X chromosome non-disjunction and may assist in counseling of families with this chromosomal rearrangement.
Reish
Orit
O
Genetic Institute, Assaf Harofeh Medical Center, Zerifin, Israel. oreish@post.tau.ac.il
Berryman
Todd
T
Cunningham
Thomas R
TR
Sher
Carron
C
Oetting
William S
WS
D000293:Adolescent; D000328:Adult; D023902:Chromosome Pairing; D020090:Chromosome Segregation; D041321:Chromosomes, Human, X; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D010375:Pedigree; D035781:Siblings; D014314:Trisomy