The Clinical and Laboratory Profiles of a Deletional α2-Globin Gene Polyadenylation Signal Sequence (AATAAA > AATA--) [HBA2:c.*93_*94delAA]: The Malaysian Experience

The Clinical and Laboratory Profiles of a Deletional α2-Globin Gene Polyadenylation Signal Sequence (AATAAA > AATA--) [HBA2:c.*93_*94delAA]: The Malaysian Experience

Poly A (AATAAA > AATA--) [HBA2:c.*93_*94delAA] is a rare α-variant reported in our population. It is caused by 2 bp deletion (--AA) in the α2 poly A sequence, leading to a significant α–thalassaemia phenotype. <b>Background/Objectives</b>: This study describes the haematological param...

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Main Authors: Norafiza Mohd Yasin, Syahzuwan Hassan, Nur Aisyah Aziz, Faidatul Syazlin Abdul Hamid, Ezalia Esa, Ezzanie Suffya Zulkefli, Rohana Ghazali, Syirah Nazirah Tajuddin, Mohd Nazif Darawi, Yuslina Mat Yusoff, Cornelis L. Harteveld
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Diagnostics
Subjects:
non-deletional α-thalassaemia
polyadenylation mutation
AATA( > AA)
Hb H disease
Online Access:https://www.mdpi.com/2075-4418/15/10/1284
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Summary:Poly A (AATAAA > AATA--) [HBA2:c.*93_*94delAA] is a rare α-variant reported in our population. It is caused by 2 bp deletion (--AA) in the α2 poly A sequence, leading to a significant α–thalassaemia phenotype. <b>Background/Objectives</b>: This study describes the haematological parameters, phenotype, and genotype characteristics of AATA(--AA) in the Malaysian population. <b>Methods</b>: The study was carried out on 17 177 cases referred to the Institute for Medical Research, Malaysia, for further diagnosis of α-thalassaemia in a five-year period. Alpha-Gap and ARMS-PCR were performed to detect common α-thalassaemia, followed by <i>HBA1</i> and <i>HBA2</i> genes sequencing and multiplex ligation-dependent probe amplification (MLPA). Haematological parameters among various groups with the AATA(--AA) allele were presented in this study. <b>Results</b>: Thirty-two patients with AATA(--AA) displaying an α–thalassaemia-like phenotype were analysed. They comprised 22 (68.75%) AATA(--AA) carriers, 2 (6.25%) compounds with 3.7 deletion, 2 (6.25%) compounds with --SEA deletion, 1 (3.12%) AATA(--AA) homozygote, and 3 (9.37%) compounds of Hb Adana, Hb CS, and Hb Pakse with co-inheritance Hb E, respectively. Most of the patients with AATA(--AA) compounds with the α-variant exhibited a significant phenotype between moderate to severe thalassaemia, especially cases with compound α<sup>−AA</sup>α/α<sup>Adana</sup>α. <b>Conclusions</b>: AATA(--AA) is a significant pathogenic variant that should be diagnosed to prevent significant thalassaemia phenotype or transfusion-dependent thalassaemia.
ISSN:2075-4418

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