Women with mosaic Turner syndrome who undergo in vitro fertilization produce fewer blastocysts than women with a normal karyotype, and the disadvantage grows as the proportion of cells carrying the chromosomal alteration increases. That is the central finding of a retrospective study that compared treatment outcomes in 99 patients with mosaic Turner syndrome and 198 women with a normal karyotype, matched one to two by propensity score.
The analysis covered in vitro fertilization and embryo transfer cycles performed between January 2022 and October 2024. Patients with Turner syndrome were further divided into two subgroups according to the extent of mosaicism: those with fewer than 10% abnormal cells and those with 10% or more. The aim was twofold: to establish whether ovarian response and oocyte and embryo quality differed from the general population, and to determine whether the degree of mosaicism influenced the outcome.
The clearest difference emerged in the blastocyst rate: 43.45% in the Turner syndrome group versus 51.40% in controls, a statistically significant gap. When the groups were split by degree of mosaicism, the contrast sharpened: patients with high mosaicism — 10% or more abnormal cells — reached a blastocyst rate of 38.39%, compared with 48.76% in the low-mosaicism group. In other words, blastocyst formation declined progressively as the proportion of cells with the affected X chromosome rose.
All other indicators, however, showed no significant differences between groups or subgroups. There were no disparities in the rate of metaphase II oocytes, normal fertilization, cleavage-stage embryos, the proportion of cleavage embryos or high-quality blastocysts. Nor were differences found in clinical pregnancy, live birth, miscarriage, complications during pregnancy, or the weight and height of newborns.
The results refer to the first embryo transfer cycle, so they describe the initial performance of treatment rather than the cumulative outcome across several attempts. For families and fertility teams, the practical message is twofold: mosaic Turner syndrome may be associated with fewer available blastocysts — relevant when planning the number of cycles and oocytes needed — but once a viable embryo is obtained, the chances of pregnancy and birth do not appear to differ from the general population in this sample. The degree of mosaicism thus emerges as a useful variable for individualizing reproductive counseling.
Source: Outcomes of IVF-ET in patients with mosaic Turner syndrome: a retrospective study. He L, Xiang Y, We J, He L, Qiu Y, Luo T, Wang L, Wang N, Li-Ling J, Gong Y. Journal of Assisted Reproduction and Genetics 2026. DOI: 10.1007/s10815-026-04035-5.
