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Updated: Jul 31, 2026
07:34
FISH for Pre-implantation Genetic Diagnosis
Published on: February 24, 2011
Tetrasomy 9p mosaicism associated with a normal phenotype.
Fionnuala McAuliffe1, Elizabeth J T Winsor, David Chitayat
1Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Canada.
Fetal Diagnosis and Therapy
|April 13, 2005
Summary
Isochromosome (tetrasomy) 9p mosaicism can result in a normal phenotype in adult males, despite potential fertility issues like oligospermia. This rare chromosomal aberration highlights the importance of considering tissue-specific expression in genetic testing.
Area of Science:
- Genetics
- Human Chromosome Abnormalities
- Reproductive Biology
Background:
- Isochromosome (tetrasomy) 9p is a rare chromosomal aberration associated with a spectrum of developmental abnormalities.
- Phenotypic variability ranges from mild developmental delay to multiple congenital anomalies.
Observation:
- A case of isochromosome (tetrasomy) 9p mosaicism in a healthy adult male is presented.
- The patient exhibits oligospermia but has successfully fathered two normal children.
Findings:
- Mosaicism for isochromosome (tetrasomy) 9p can present with a normal phenotype.
- The chromosomal abnormality demonstrates tissue specificity, with higher detection rates in lymphocytes than fibroblasts.
- Prenatal diagnosis may be challenging due to potential underdetection in amniotic fluid or chorionic villus samples.
Implications:
- This case expands the known phenotypic spectrum of isochromosome (tetrasomy) 9p mosaicism.
- Highlights the potential for individuals with chromosomal mosaicism to have normal development and reproductive capacity.
- Underscores the diagnostic challenges and the need for careful interpretation of genetic testing results, especially in prenatal settings.
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