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Mosaic Turner syndrome: cytogenetics versus FISH
S J Abulhasan1, S M Tayel, S A al-Awadi
1Kuwait Medical Genetics Centre, Maternity Hospital, Kuwait. saw@qualitynet.net
Annals of Human Genetics
|March 30, 2000
Summary
Fluorescence in situ hybridization (FISH) improved Turner syndrome diagnosis by identifying additional cell lines and clarifying marker origins, surpassing standard GTG-banding in accuracy. This advanced technique is crucial for precise genetic analysis in Turner patients.
Area of Science:
- Cytogenetics
- Human Genetics
- Molecular Biology
Background:
- Turner syndrome presents with diverse cytogenetic abnormalities.
- Standard GTG-banding may miss low-frequency cell lines or complex rearrangements.
- Accurate karyotyping is essential for clinical management and risk assessment.
Purpose of the Study:
- To compare the diagnostic efficacy of GTG-banding and FISH in Turner syndrome.
- To evaluate FISH's ability to detect cryptic abnormalities and clarify marker origins.
- To assess FISH for identifying Y chromosome material and deletions in 45,X/46,XY Turner patients.
Main Methods:
- Twenty-two Turner syndrome cases were analyzed using GTG-banding and FISH.
- FISH utilized whole-X chromosome painting, Y-specific probes (AMELY, DYZ3), and X/Y cocktail probes.
- Techniques were compared for detecting cell lines, marker origins, and Y chromosome regions.
Main Results:
- Both techniques yielded identical results in 36% of cases.
- FISH identified a third cell line in 32% of cases missed by GTG-banding.
- FISH delineated marker origins in 23% of cases and clarified Yp11.2 deletions in 9% of 45,X/46,XY patients.
Conclusions:
- FISH significantly enhances diagnostic accuracy in Turner syndrome compared to GTG-banding alone.
- FISH is crucial for detecting low-frequency mosaicism and characterizing complex chromosomal rearrangements.
- Accurate genetic delineation using FISH has implications for gonadal tumor risk assessment in Turner syndrome.