α-Globin Genotypes Associated with Hb H Disease: A Report from Oman and a Review of the Literature from the Eastern Mediterranean Region

Arwa Z. Al-Riyami, Shahina Daar, Salam Al Kindi, Ali Al Madhani, Yasser Wali, Mohammed Al Rawahi, Shoaib Al Zadjali*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

α-Thalassemia (α-thal) is the most common autosomal recessive hemoglobinopathy. There is a vast diversity and geographical variability in underlying genotypes in Hb H (β4) patients. Herein, we describe the genotypes found in the largest report of Omani Hb H patients. Moreover, we reviewed and summarized the literature published from the Eastern Mediterranean region. A retrospective review of all genetically confirmed Hb H disease patients diagnosed between 2007 and 2017 at Sultan Qaboos University Hospital, Muscat, Oman, was performed. Hematological parameters and clinical presentations were assessed. Both α-globin genes were screened for deletional and nondeletional mutations using a stepwise diagnostic strategy as described before. A total of 52 patients (27 females and 25 males) with a mean age of 20.6 years (range 0.23–80.0) were molecularly confirmed to carry Hb H disease. The patients had a hemoglobin (Hb) level of 9.3 g/dL (range 5.7–13.0) and mean corpuscular volume (MCV) of 58.4 fL (range 48.2–82.1). A total of eight genotype combinations were identified, with α2 polyadenylation signal mutation (polyA1) (AATAAA>AATAAG (αPA1α/αPA1α), often cited as αT-Saudiα/αT-Saudiα, being the most common (53.8%) followed by –α3.7/– –MED I (28.8%). Our cohort also included patients with combinations of αPA1 with other Hb variants: αPA1α/αPA1α with Hb S (HBB: c.20A>T) trait (n = 2), –α3.7PA1α (n = 2) and αcodon 19α (HBA2: c.56delG)/αPA1α (n = 1). Nondeletional Hb H disease due to the αPA1 mutation is the most common in Omanis. Molecular diagnosis is necessary for accurate confirmation of the diagnosis of α-thal, determination of underlying genotypes, follow-up and counseling.

Original languageEnglish
Pages (from-to)20-26
Number of pages7
JournalHemoglobin
Volume44
Issue number1
DOIs
Publication statusPublished - Jan 2 2020
Externally publishedYes

Keywords

  • Hemoglobinopathy
  • molecular genetics
  • thalassemia

ASJC Scopus subject areas

  • Hematology
  • Clinical Biochemistry
  • Genetics(clinical)
  • Biochemistry, medical

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