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Mosaic normal/15q11-q13 duplication associated with developmental delay but normal phenotype
E Goossens1, P Decock, S Potgieter
1Center for Human Genetics, University of Leuven, Belgium.
Genetic Counseling (Geneva, Switzerland)
|July 28, 1999
Summary
A proximal duplication in chromosome 15 (15q11-15q13) was identified in a boy with developmental delay and seizures. This genetic finding occurred in mosaic form alongside a normal cell line.
Area of Science:
- Human Genetics
- Chromosomal Abnormalities
- Developmental Biology
Background:
- Chromosome 15 duplications are rare genetic alterations.
- Mosaicism involves the presence of two or more cell lines with different genetic makeup within an individual.
- Proximal duplications in the 15q11-15q13 region are associated with specific neurodevelopmental phenotypes.
Observation:
- A 4-year-old boy presented with developmental delay and a history of seizures.
- Clinical examination revealed a normal phenotype despite the neurological symptoms.
- Karyotyping or chromosomal microarray analysis detected a mosaic proximal duplication of chromosome 15 (15q11-15q13).
Findings:
- The genetic analysis confirmed a mosaic duplication in the 15q11-15q13 region.
- The presence of both duplicated and normal cell lines (mosaicism) was a key finding.
- The duplication occurred proximally on the long arm of chromosome 15.
Implications:
- This case highlights the importance of genetic testing in children with unexplained developmental delay and seizures.
- Mosaic chromosomal duplications can lead to variable clinical presentations, even with a normal phenotype.
- Understanding the spectrum of 15q duplications is crucial for genetic counseling and clinical management.