Related Experiment Videos
E trisomy phenotype associated with small metacentric chromosome and a familial Y-22 translocation
Insights
An extra metacentric D or E chromosome can lead to various conditions, including E 18 trisomy-like phenotypes, developmental delays, and normal phenotypes with chromosomal abnormalities. These findings highlight complex genetic links.
Area of Science:
- Genetics
- Human Genetics
- Cytogenetics
Background:
- Extra metacentric chromosomes, specifically D or E types, are rare chromosomal abnormalities.
- Understanding the phenotypic consequences of these extra chromosomes is crucial for genetic diagnosis and counseling.
Observation:
- This case report details several postulated entities arising from an extra metacentric D or E chromosome.
- Observed phenotypes range from E 18 trisomy-like presentations to developmental delays and normal phenotypes with specific chromosomal findings.
Findings:
- Infants may exhibit phenotypes similar to E 18 trisomy, with karyotypes interpretable as deleted E or D chromosomes.
- Children can present with mental retardation, facial asymmetry, scoliosis, and cerebral palsy due to partial trisomy of E 16 or E 17.
- Individuals with normal phenotypes may have an additional satellited metacentric chromosome (centric fusion of D or G), and affected children can have inconsistent phenotypes with extra chromosomes showing satellites.
Implications:
- These findings suggest a complex relationship between extra metacentric chromosomes and a spectrum of phenotypic outcomes.
- The presence of the same abnormality in unaffected relatives indicates potential reduced penetrance or variable expressivity.
- Further research is needed to fully elucidate the mechanisms and clinical significance of these chromosomal variations.
Abstract:
As a result of this case report, several entities are postulated due to an extra metacentric D or E chromosome: 1) infants presenting with a phenotype similar to the E 18 trisomy; however, the karyotype can be interpreted as either a deleted E or D chromosome; 2) another group of children all presenting with mental retardation, facial asymmetry, scoliosis and cerebral palsy, postulated due to a partial trisomy of E 16 or E 17; 3) individuals with a normal phenotype, but chromosomally presented with an additional satellited metacentric chromosome consistent with centric fusion of a D or G chromosome and 4) children presenting with an inconsistent phenotype and chromosomally presenting with an extra chromosome manifesting satellites or satellite association; the same chromosome abnormality often is found in unaffected parents and/or sibs.