Karyotype-based evaluation of ovarian reserve before ovarian tissue cryopreservation in Turner syndrome patients

Turner syndrome (TS) girls experience accelerated ovarian reserve depletion, exhibiting a strong demand for ovarian tissue cryopreservation (OTC) to preserve fertility and ovarian function. However, the current knowledge of OTC in TS is limited, and predicting follicular presence is insufficient. This study aims to investigate ovarian follicular reserve based on karyotypes, thereby contributing empirical data to informed decision-making in TS populations. The retrospective case-control study comprised 26 TS patients and 52 age-matched non-TS (NTS) controls who underwent OTC between January 2022 and March 2025. The TS cohort included 45,X (n = 2), 45,X/46,XX (n = 6), and ‘other’ (n = 18), the latter encompassing 7 cases with 47,XXX mosaicism and 11 with structural X-chromosome abnormalities (SCA). Ovarian volume, estimated total follicle count (TFC), anti-Müllerian hormone (AMH), and follicle-stimulating hormone (FSH) were compared between the TS and NTS across age cohorts (0–5, 6–10, and > 10 years), and further analyzed across TS karyotype categories. Follicles were found in 91.7% of TS cases. Estimated TFC in TS showed no significant difference from NTS in the 0–5 age group. However, it was significantly reduced in TS aged 6–10 and > 10 years, reaching only 1.2% and 4.6% of NTS estimated TFC, respectively. The FSH levels (range 0.83–13.55 IU/L) in TS patients were elevated but below the diagnostic threshold for premature ovarian insufficiency, despite the absence of detectable follicles. No correlation was observed between AMH and estimated TFC. When comparing parameters across different karyotypes, the 45,X/46,XX group had the highest AMH, ovarian volume, and estimated TFC, which declined sharply with age (r = -0.858). Patients with a 45,X karyotype exhibited bilateral streak ovaries and no follicles. In 45,X/47,XXX, estimated TFC correlated positively with ovarian volume, independent of age (r = 0.922). TS with SCA generally exhibited low estimated TFC and AMH. Our findings suggest that ovarian reserve in TS is associated with karyotype, supporting the need for individualized counseling regarding OTC. Girls with 45,X appear to have a low probability of retaining follicles. For those with 45,X/46,XX mosaicism, the observed rapid decline in ovarian reserve suggests that timely consideration of OTC may be beneficial. In patients with 45,X/47,XXX, ovarian volume may be a helpful indicator for estimating TFC, potentially supporting OTC while ovarian volume remains substantial. Patients with SCA generally presented with reduced ovarian reserve in this study.