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Blood Cells Mol Dis. 2014 Jan;52(1):46-9. doi: 10.1016/j.bcmd.2013.06.004. Epub 2013 Jul 27.

Complexity of the alpha-globin genotypes identified with thalassemia screening in Sardinia.

Author information

1
Clinica Pediatrica 2°, Dipartimento di Sanità Pubblica, Medicina Clinica e Molecolare, Università di Cagliari, Ospedale Regionale per le Microcitemie, ASL 8 Cagliari, Italy. Electronic address: secondacasella@hotmail.com.

Abstract

α-Thalassemia commonly results from deletions or point mutations in one or both α-globin genes located on chromosome 16p13.3 giving rise to complex and variable genotypes and phenotypes. Rarely, unusual non-deletion defects or atypical deletions down-regulate the expression of the α-globin gene. In the last decade of the program for β-thalassemia carrier screening and genetic counseling in Sardinia, the association of new techniques of molecular biology such as gene sequencing and Multiplex Ligation-dependent Probe Amplification (MLPA) to conventional methods has allowed to better define several thalassemic genotypes and the complex variability of the α-cluster with its flanking regions, with a high frequency of different genotypes and compound heterozygosity for two α mutations even in the same family. The exact molecular definition of the genotypes resulting from the interactions among the large number of α-thalassemia determinants and with β-thalassemia, is important for a correct correlation of genotype-phenotype and to prevent underdiagnosis of carrier status which could hamper the effectiveness of a screening program particularly in those regions where a high frequency of hemoglobinopathies is present.

KEYWORDS:

Additional alpha globin genes; Alpha thalassemia; Compound heterozygosity; Hb-variants

PMID:
23896219
DOI:
10.1016/j.bcmd.2013.06.004
[Indexed for MEDLINE]

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