Copy number variations of six and seven α-globin genes in a family with intermedia and major thalassemia phenotypes.

Abstract

BACKGROUND:

Copy number variations in α-globin genes are results of unequal crossover between homologous segments in the α-globin gene cluster that misalign during the meiosis phase of the gametogenesis process. Reduction or augmentation of α-globin genes leads to imbalance of α/β chains in hemoglobin tetramer and consequently attenuate or worsen the β-thal clinical symptoms, respectively.

OBJECTIVE:

Multiplications in α-globin genes have been found in some populations, justifying unexpected severe phenotype of β-thal carriers.

STUDY DESIGN:

Unexpected severe phenotype in the family members may result from coexistence of extra α-globin genes, which is an important factor in the causation of thalassemia intermedia and major in heterozygous β-thalassemia.

RESULTS:

We described different multiplications in α-globin locus in an Iranian family with one, two or three extra α-globin genes (ααα/αα, αααα/αα and αααα/ααα).

CONCLUSION:

The excess α-globin gene/genes cause increment in β/α chain imbalance and leads to worsening pathophysiology and clinical severity of β-thalassemia carriers.

• Authors: Samaneh Farashi, Shadi Vakili, Negin Faramarzi Garous, Mehri Ashki, Hashem Imanian, Azita Azarkeivan, Hossein Najmabadi
• Journal: Expert review of hematology (Expert Rev Hematol) Vol. 8 Issue 5 Pg. 693-8 (Oct 2015) ISSN: 1747-4094 [Electronic] England
• PMID: 26343893 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)

Chemical References

• alpha-Globins

Topics

• DNA Copy Number Variations
• Gene Dosage
• Gene Duplication
• Gene Rearrangement
• Genetic Loci
• Genetic Testing
• Heterozygote
• Humans
• Multigene Family
• Mutation
• Phenotype
• Severity of Illness Index
• alpha-Globins (genetics)
• beta-Thalassemia (diagnosis, genetics)