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Breakpoints around the HOXD cluster result in various limb malformations
B Dlugaszewska1, A Silahtaroglu, C Menzel
1Max Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany.
Journal of Medical Genetics
|June 28, 2005
Summary
Balanced chromosome rearrangements near the HOXD gene cluster can cause limb abnormalities by disrupting gene regulation. These findings highlight the role of HOXD genes in bone development and suggest position effects are key.
Area of Science:
- Genetics
- Developmental Biology
- Human Disease
Background:
- Balanced chromosome rearrangements are valuable for identifying genes and regulatory elements linked to diseases.
- Investigating these rearrangements provides insights into genetic contributions to developmental abnormalities.
Observation:
- Three patients with limb abnormalities and breakpoints at chromosome 2q31 were studied.
- Patient 1 had a t(2;10)(q31.1;q26.3) translocation with syndactyly, mental retardation, and cerebellar hypoplasia.
- Patient 2 had a t(2;10)(q31.1;q23.33) translocation with ulna aplasia and radius shortening.
- Patient 3 had an inv(2)(p15q31) inversion with bilateral fibula and radius aplasia, and ulna hypoplasia.
Findings:
- Fluorescence in situ hybridization mapped breakpoints to within 170 kb.
- None of the 2q31 breakpoints disrupted known genes.
- All breakpoints were located near the HOXD gene cluster.
Implications:
- Hoxd gene expression is regulated by distant cis-acting elements.
- Hoxd genes are crucial for bone development.
- The observed rearrangements likely disrupt normal HOXD gene regulation through position effects, leading to limb malformations.