Reproductive potential in mosaic Turner syndrome: impact of karyotype pattern and mosaicism ratio

This study aimed to evaluate reproductive potential in women with Turner syndrome (TS), focusing on 45,X/46,XX mosaicism and the impact of mosaic ratio on reproductive outcomes.

The study retrospectively analyzed 145 TS patients diagnosed postnatally by peripheral blood karyotyping from January 1990 to May 2023. Karyotypes were categorized into 45,X monosomy, 45,X mosaicism with Y chromosome and 45,X mosaicism without Y chromosome.

The predominant karyotype was 45,X/46,XX mosaicism (71.0%), accounting for most cases with preserved reproductive potential. Within this subgroup, spontaneous menarche (SM) occurred in 97.7% of cases with <40% 45,X cells, while 84.2% of pregnancies occurred in those with <10% 45,X cells. Among patients aged ≥15 years with mosaic karyotypes containing 46,XX and no structural abnormalities, SM occurred in 95.3% of those with <40% 45,X cells, but in none with ≥40% (p < 0.001). In contrast, cases of 45,X monosomy, Y-containing mosaicism, structural X abnormalities, 45,X/46,X with marker chromosomes or 45,X/47,XXX showed no pregnancies and minimal SM. Recurrent pregnancy loss (RPL) was the diagnostic indication in 34% of cases, likely enriching milder mosaicism.

Women with 45,X/46,XX mosaicism retain reproductive potential, particularly when 45,X cell ratios are low. Early diagnosis via peripheral blood karyotyping supports timely fertility counseling and ovarian care.