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Small marker chromosomes in two patients with segmental aneusomy for proximal 17p
Christine J Shaw1, Pawel Stankiewicz, Gabriel Bien-Willner
1Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, TX 77030, Houston, USA.
Human Genetics
|April 21, 2004
Summary
Two children with supernumerary marker chromosomes (SMCs) involving 17p10-p11.2 exhibit developmental delays and distinct facial and limb anomalies. These findings help delineate the phenotype of trisomy 17p10-p11.2.
Area of Science:
- Genetics
- Human Genetics
- Molecular Cytogenetics
Background:
- Supernumerary marker chromosomes (SMCs) are rare chromosomal abnormalities.
- Understanding the genetic basis of developmental disorders is crucial for diagnosis and management.
Observation:
- Two pediatric patients, a 9-year-old girl and a 5-year-old boy, presented with de novo SMCs derived from proximal 17p.
- Patient 1934 displayed developmental delay, dysmorphic facial features, dental issues, and joint laxity.
- Patient 2170 showed developmental delay, verbal apraxia, characteristic lip morphology, clinodactyly, and joint laxity.
Findings:
- G-banded analysis revealed mosaicism for the SMC in patient 1934 (72%) and its presence in all cells of patient 2170 (100%).
- Fluorescence in situ hybridization (FISH) confirmed both SMCs originated from 17p10-p11.2.
- FISH and array comparative genomic hybridization (array-CGH) mapped breakpoints to the centromere and the Smith-Magenis syndrome (SMS) common deletion region.
Implications:
- This study contributes to delineating the phenotype associated with trisomy 17p10-p11.2.
- Comparing these cases with prior reports aids in understanding genotype-phenotype correlations for proximal 17p duplications and SMCs.
- Further research can refine diagnostic criteria and genetic counseling for individuals with these rare chromosomal alterations.