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Genomic analysis of partial 21q monosomies with variable phenotypes
Elisha D O Roberson1, Elizabeth Squibb Wohler, Julie E Hoover-Fong
1Program in Human Genetics, Johns Hopkins School of Medicine, Baltimore, MD, USA.
European Journal of Human Genetics : EJHG
|September 9, 2010
Summary
Partial chromosome 21 monosomy deletions, particularly terminal ones, are linked to milder phenotypes. However, deletions in other regions are viable and show varied clinical outcomes, influenced by genetic and environmental factors.
Area of Science:
- Genetics
- Human Genetics
- Molecular Biology
Background:
- Partial monosomy 21 has been categorized into three distinct regions, each correlating with varying degrees of clinical severity.
- Understanding the genotypic and phenotypic correlations in partial chromosome 21 monosomies is crucial for accurate diagnosis and genetic counseling.
Purpose of the Study:
- To describe 10 new patients with partial chromosome 21 monosomies.
- To correlate specific deletion regions with clinical phenotypes.
- To review existing data and confirm findings in a larger cohort.
Main Methods:
- Single nucleotide polymorphism (SNP) genotyping and G-banded karyotyping were performed on new patients.
- Data from new cases, the Coriell Genetic Cell Repository, and the DECIPHER database were analyzed.
- Phenotypic features and deletion breakpoints were meticulously documented and compared.
Main Results:
- Three patients with terminal deletions (21q22.2-ter and 21q22.3-ter) exhibited mild phenotypes.
- One patient with an interstitial deletion (21q21.1-q22.11) also presented with a mild phenotype.
- Analysis of 36 cases indicates that terminal deletions are associated with mild phenotypes, while deletions in regions 1 and 2 are compatible with life and present variable phenotypes.
Conclusions:
- Deletion of the terminal region of chromosome 21 is consistently linked to a mild clinical presentation.
- Deletions in chromosome 21 regions 1 and 2, while compatible with life, result in variable phenotypes.
- Phenotypic variability in partial monosomy 21 may be influenced by factors beyond the deleted genes, including other genetic and environmental influences.
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