Clinical and Cytogenetic Evaluation of a Case with Mosaic 45,X/46,X,i(Y) Karyotype

Öz

Turner syndrome (TS) is a chromosomal disorder that affects only females and is typically characterized by a 45, X karyotype. In addition to the classic form, TS may present with various karyotypes. In this study, we report a rare mosaic karyotype, 45, X/46, X, i(Y)(p), identified in an 8-year-old girl who was referred for evaluation due to a preliminary diagnosis of TS. Conventional cytogenetic and FISH analyses revealed that 80% of the cells harbored an isochromosome Yp structure containing the SRY gene but lacking the Yq12 region. The clinical phenotype was completely female, and no follicles were observed in the ovaries on pelvic ultrasound. Due to the presence of Y chromosomal material, the patient was evaluated for the risk of gonadoblastoma and underwent prophylactic gonadectomy. This rare case highlights the importance of utilizing both karyotyping and FISH analysis in the diagnostic evaluation of Turner syndrome.Moreover, the case may also be considered within the spectrum of mixed gonadal dysgenesis (MGD), emphasizing the need for careful clinical and cytogenetic assessment.

Anahtar Kelimeler

• Turner syndrome
• isochromosome
• karyotype
• FISH (Fluorescence ın situ hybridization)

Kaynakça

1. 1. Gravholt CH, Viuff MH, Brun S, Stochholm K, Andersen NH. Turner syndrome: mechanisms and management. Nat Rev Endocrinol. 2019;15(10):601–614. https://doi.org/10.1038/ s41574-019-0224-4
2. 2. Wolff DJ, Van Dyke DL, Powell CM. Laboratory guideline for Turner syndrome. Genet Med. 2010;12:52–55. https://doi.org/10.1097/GIM.0b013e3181c684b2
3. 3. Gravholt CH, Andersen NH, Conway GS, Dekkers OM, Geffner ME, Karen O Klein, et al. Clinical practice guidelines for the care of girls and women with Turner syndrome: proceedings from the 2016 Cincinnati International Turner Syndrome Meeting. Eur J Endocrinol. 2017;177(3):G1–G70. https://doi.org/10.1530/EJE-17-0430
4. 4. Yoon SH, Kim GY, Choi GT, Do JT. Organ abnormalities caused by Turner syndrome. Cells. 2023;12(10):1365. https://doi.org/10.3390/cells12101365
5. 5. Oliveira RM, Verreschi IT, Lipay MV, Eça LP, Guedes AD, Bianco B. Y chromosome in Turner syndrome: review of the literature. Sao Paulo Med J. 2009;127(6):373–378. https://doi. org/10.1590/S1516-31802009000600010
6. 6. Abacı A, Çatlı G, Berberoğlu M. Gonadal malignancy risk and prophylactic gonadectomy in disorders of sexual development. J Pediatr Endocrinol Metab. 2015;28(9-10):1019–1027. https://doi.org/10.1515/jpem-2014-0522
7. 7. Ferguson-Smith MA, Boyd E, Ferguson-Smith ME, Pritchard JG, Yusuf AF, Gray B. Isochromosome for long arm of Y chromosome in patient with Turner’s syndrome and sex chromosome mosaicism (45, X-46, XY qi). J Med Genet.1969;6(4):422–425. https://doi.org/10.1136/jmg.6.4.422
8. 8. Reshmi SC, Miller JL, Deplewski D, Close C, Henderson LJ, Littlejohn E, et al. Evidence of a mechanism for isodicentric chromosome Y formation in a 45, X/46, X, idic (Y) (p11.31)/46, X, del (Y) (p11. 31) mosaic karyotype. Eur J Med Genet.2011;54(2):161–164. https://doi.org/10.1016/j.ejmg.2010.11.002

9. 9. Canto P, Kofman-Alfaro S, Jiménez AL, Söderlund D, Barrón C, Reyes E, et al. Gonadoblastoma in Turner syndrome patients with non-mosaic 45, X karyotype and Y chromosome sequences. Cancer Genet Cytogenet. 2004;150(1):70–72. https://doi.org/10.1016/j.cancergencyto.2003.08.011
10. 10. Krausz C, Abrardo C. The Y chromosome: male reproduction and beyond. Fertil Steril. 2025;123(6):921–932. https://doi.org/10.1016/j.fertnstert.2025.03.006