Y-Chromosome in Turner Syndrome: What Is the Risk?

When a doctor says a girl with Turner syndrome has “Y-chromosome material,” it means that some of her cells contain a complete or partial Y chromosome, rather than only the typical X chromosome. While this does not change her identity as a girl, it does significantly increase her risk of developing a specific type of tumor in her ovaries called a gonadoblastoma. Because these tumors can eventually become cancerous, clinical guidelines strongly recommend a preventative surgery called a prophylactic gonadectomy to remove the undeveloped ovaries and eliminate this risk.

What Does “Y-Chromosome Material” Mean?

Typically, girls with Turner syndrome are missing all or part of an X chromosome (a 45,X karyotype). However, genetics can be complex. In a condition known as mosaicism (where different cells in the body have different genetic makeups), some cells might have the typical 45,X pattern, while others contain a complete Y chromosome (like a 46,XY pattern) or parts of a Y chromosome ^[1][2].

Because girls with Turner syndrome usually have undeveloped ovaries (often called streak ovaries), the presence of Y-chromosome pieces—specifically a region on the Y chromosome known as the GBY region—can cause these tissues to develop abnormally ^[3][4].

The Risk of Gonadoblastoma

The primary concern with having Y-chromosome material is a high risk of developing gonadoblastoma ^[5][3].

• What is a gonadoblastoma? It is a rare, usually non-cancerous (benign) tumor that grows in abnormally developed reproductive organs ^[6].
• What is the risk? Studies show that between 19% and 30% of individuals with Turner syndrome and Y-chromosome material will develop these tumors ^[7][8].
• Can it become cancer? Yes. While gonadoblastomas start as benign, if they are left in the body, they have a high chance of transforming into a malignant (cancerous) tumor called a dysgerminoma ^[9][8].

These tumors can develop early in life, even before a child reaches puberty ^[10]. Furthermore, they are often too small to be seen on a standard pelvic ultrasound, which makes them difficult to monitor safely ^[9][11].

Preventative Surgery (Prophylactic Gonadectomy)

Because the tumor risk is significant and hard to track, international clinical guidelines recommend a preventative surgery called a prophylactic gonadectomy ^[9][12].

• What does the surgery involve? A surgeon will remove the streak ovaries. This is usually done laparoscopically, meaning the surgeon uses small keyhole incisions and a camera. This approach generally allows for a faster and easier recovery with minimal scarring ^[13].
• Who performs the surgery? This procedure should be performed by a skilled laparoscopic surgeon who specializes in children, such as a pediatric surgeon or a pediatric gynecologist ^[13].
• When should it happen? Guidelines typically suggest performing this surgery promptly after the Y-chromosome material is discovered ^[10][9]. While this is not an emergency that requires rushing to the hospital today, it is a priority surgery that your medical team will likely want to schedule in the near future to safely remove the risk before any tumor can grow.

Looking Ahead: Hormones and Future Family Planning

Removing the ovaries means your daughter will not produce her own estrogen. However, most girls with Turner syndrome already need hormone replacement therapy (HRT) to induce puberty and support bone health, so this surgery will not change her long-term need for these standard treatments ^[14][15].

When thinking about her future fertility, it is important to know that attempting to freeze your daughter’s ovarian tissue (ovarian tissue cryopreservation) is generally avoided when Y-chromosome material is present. This is because reimplanting that tissue later could accidentally reintroduce tumor cells into her body ^[9][8]. Instead, reassure her that when she is older, there are safe, common, and highly successful ways for individuals with Turner syndrome to build families, such as using donor eggs or through adoption.