Fragmented X chromosome forming a portrait, symbolizing Turner Syndrome diagnosis.

Unlocking the Genetic Puzzle of Turner Syndrome: What Prenatal vs. Postnatal Diagnosis Reveals

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Jordan Keane in Health & Wellness December 2025 • 4 min read.

"A Deep Dive into Cytogenetic Variations and Their Implications for Diagnosis and Management"


Turner Syndrome (TS) is a genetic condition stemming from the partial or complete absence of the X chromosome. This leads to a range of characteristics, including short stature, primary amenorrhea, and other physical differences like a webbed neck or cubitus valgus. Early suspicion and diagnosis are crucial, especially when prenatal ultrasounds reveal signs like cystic hygroma, non-immune hydrops, or other non-specific anatomical abnormalities, such as heart defects or intrauterine growth restriction.

Affecting approximately 1 in 2,000 to 5,000 newborn females, Turner Syndrome is even more prevalent in early conceptions, with estimates suggesting that as many as 3% of female embryos and fetuses are affected. Sadly, the vast majority (95-99%) of these pregnancies end in spontaneous abortion during the first trimester, highlighting the challenges associated with this condition.

One of the key complexities of Turner Syndrome is its varied cytogenetic presentation. While about half of those affected have a complete absence of one X chromosome (45,X0), the other half exhibit mosaicism, partial deletions, translocations, ring chromosomes, or other complex rearrangements. Understanding these variations is vital for predicting the severity of the condition and potential health outcomes.

Why Cytogenetic Variations Matter in Turner Syndrome?

Fragmented X chromosome forming a portrait, symbolizing Turner Syndrome diagnosis.

Identifying specific cytogenetic presentations is important because structural abnormalities or mosaicism involving a 46,XX cell line are often associated with a milder phenotype and reduced fetal mortality compared to complete monosomy X. Conversely, the presence of a Y chromosome increases the risk of gonadoblastoma, a rare tumor, in up to 30% of patients.

A recent study conducted in Cali, Colombia, delved into the prevalence of different cytogenetic presentations of Turner Syndrome. The research aimed to identify variations in cytogenetic presentations among patients diagnosed with Turner Syndrome (TS) in two reference laboratories in Cali and to determine if there were significant differences between cases diagnosed prenatally versus postnatally. The descriptive study reviewed karyotype results from 2000 to 2012, and here’s what they found:

  • Study Design: A descriptive, cross-sectional study.
  • Participants: Patients diagnosed with TS based on karyotype analysis.
  • Setting: Cytogenetic laboratories at Universidad del Valle and a genetic institute in Cali, Colombia.
  • Data Collection: Retrospective collection of karyotype reports, sample types, and timing of diagnosis.
  • Analysis: Statistical analysis to determine frequencies and associations between variables.
The study included 181 patients with confirmed TS. 69 were diagnosed prenatally and 112 were diagnosed postnatally (newborns, infants, or adults). The 45,X0 chromosomal formula was found in 95.6% of prenatal diagnoses but only in 58% of postnatal diagnoses. This disparity highlights significant differences in cytogenetic presentations between the two groups (p<0.001).

What This Means for You and Your Family

The research underscores the importance of understanding the cytogenetic variations in Turner Syndrome. The significantly higher prevalence of the 45,X0 karyotype in prenatally diagnosed cases suggests a possible biological explanation related to the increased likelihood of in utero mortality with complete absence of the X chromosome. Recognizing these differences can improve diagnostic accuracy, inform genetic counseling, and guide appropriate medical management.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.4067/s0717-75262014000400005, Alternate LINK

Title: Variedad De La Presentación Citogenética En El Síndrome De Turner, Prenatal Y Postnatal

Subject: Obstetrics and Gynecology

Journal: Revista chilena de obstetricia y ginecología

Publisher: Publicidad Permanyer, SLU

Authors: Wilmar Saldarriaga, Mariana Valencia, Andrés Fandiño-Losada, Fabián Andrés Ruiz, Carolina Isaza

Published: 2014-01-01

Everything You Need To Know

1

What is Turner Syndrome?

Turner Syndrome (TS) is a genetic condition occurring when there is a partial or complete absence of an X chromosome. This leads to a range of physical characteristics such as short stature and primary amenorrhea. Early detection is critical for managing the condition and addressing potential health issues.

2

Why are the different cytogenetic presentations of Turner Syndrome important?

The difference in cytogenetic presentations matters because different presentations like structural abnormalities or mosaicism involving a 46,XX cell line, are often linked to a milder phenotype and reduced fetal mortality when compared to a complete monosomy X. Conversely, the presence of a Y chromosome raises the risk of gonadoblastoma. Knowing these variations is vital for predicting the severity of the condition and its potential outcomes.

3

What are the key differences between prenatal and postnatal diagnosis of Turner Syndrome?

Prenatal diagnosis involves identifying Turner Syndrome before birth, often through ultrasound revealing signs like cystic hygroma. Postnatal diagnosis occurs after birth, typically through karyotype analysis when there are signs such as short stature or delayed puberty. The study found differences, with 45,X0 being more common prenatally, suggesting those pregnancies with complete absence of an X chromosome are less likely to survive to term.

4

What was the methodology of the study in Cali, Colombia?

The study in Cali, Colombia, used a descriptive, cross-sectional design, reviewing karyotype results from 2000 to 2012. It included 181 patients with Turner Syndrome, comparing cytogenetic presentations between those diagnosed prenatally and postnatally. This involved collecting karyotype reports and analyzing the frequencies and associations of variables to understand differences in the cytogenetic makeup of the patients.

5

What are the implications of these findings for individuals and families affected by Turner Syndrome?

The research highlights the importance of understanding the cytogenetic variations in Turner Syndrome because the differences in cytogenetic presentations can impact clinical outcomes, including the likelihood of in utero mortality and the risk of developing specific health conditions like gonadoblastoma. Recognizing these differences improves diagnostic accuracy, informs genetic counseling, and guides medical management, allowing for better care and support for those affected and their families.

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