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Tetrasomy Y by structural rearrangement: clinical report
Martin DesGroseilliers1, Emmanuelle Lemyre, Louis Dallaire
1Département de Pathologie et Biologie Cellulaire, Université de Montréal, Canada.
American Journal of Medical Genetics
|September 5, 2002
Summary
This study reports a rare Y chromosome tetrasomy in a boy with developmental delays, characterized by an isodicentric Y chromosome. This finding contributes to understanding the phenotypic spectrum of Y chromosome tetrasomy.
Area of Science:
- Human Genetics
- Cytogenetics
- Reproductive Biology
Background:
- Poly-Y karyotypes, excluding 47,XYY, are exceptionally rare in the human population.
- Y chromosome tetrasomy is an infrequent chromosomal abnormality, with only a few cases documented, often involving structural rearrangements.
Observation:
- A 2-year-old boy presented with global psychomotor delay and was found to have a mosaic karyotype: 47,X,idic(Y)(q12)x2/45,X.
- The presence of two identical isodicentric Y chromosomes was confirmed using fluorescence in situ hybridization (FISH) and banding techniques.
Findings:
- The identified karyotype, mos 47,X,idic(Y)(q12)x2[123]/45,X[9], is only the second reported instance of this specific Y chromosome tetrasomy.
- The chromosomal anomaly is hypothesized to result from a U-type exchange, with breakpoints near the telomeric end of the Y chromosome's heterochromatic region.
- Clinical manifestations included speech delay, short stature, distinctive facial features, skeletal abnormalities, and behavioral issues.
Implications:
- This case adds valuable data to the limited understanding of Y chromosome tetrasomy and its associated phenotypic variability.
- Further research and case reporting are crucial for establishing clearer genotype-phenotype correlations in individuals with Y chromosome tetrasomy.