Masking of a β-Thalassemia Determinant by a Novel δ-Globin Gene Defect [Hb A2-Saurashtra or δ100(G2)Pro→Ser; HBD: c.301C>T] in Cis. (February 2014)

• Record Type: Journal Article
• Authors: Colaco, Stacy; Trivedi, Amee; Colah, Roshan B.; Ghosh, K.; Nadkarni, Anita H.
• Is Part Of: Hemoglobin. Volume 38:Number 1(2014)
• Page Start: 24
• Page End: 27
• Publication Date: 2014-02
• Subjects: Hemoglobinopathy -- Periodicals; Hemoglobin -- Periodicals; Hematology -- Periodicals; Thalassemia -- Periodicals; Blood -- Diseases -- Periodicals; 612.1111
• DOI: 10.3109/03630269.2013.852568
• Languages: English
• ISSNs: 0363-0269

Abstract

<abstract> <title>Abstract</title> <p>The molecular basis of β-thalassemia (β-thal) syndromes have been well documented, while the spectrum of mutations causing δ-thalassemia (δ-thal) has not been well characterized. δ-Thalassemia has no clinical symptoms but its coinheritance with heterozygous β-thal may cause misdiagnosis, especially in countries with a high prevalence of β-thal where prevention programs have been implemented. The coinheritance of β- and δ-globin mutations in India is not common. This association may interfere with correct diagnosis and genetic counseling of β-thal in screening programs. Here we report two families showing borderline Hb A<sub>2</sub> levels belonging to the Koli Community, indigenous to the Saurashtra Province of Gujarat, India. They were referred to us for thalassemia molecular screening as they had children clinically presenting before 2 years of age and requiring regular blood transfusions. Interestingly, both families carried a novel δ-globin gene mutation at codon 100 (C>T) linked to a polyadenylation (polyA) site [AATAAA>A(–AATAA)] 5 bp deletional β-thal mutation, never before reported in the Indian population. This report highlights the importance of considering δ-globin gene analysis during β-thal screening to avoid false-negative results in the detection of at-risk couples. It also highlights how incomplete diagnosis of a borderline or normal Hb A<sub>2</sub> level may lead to the probable birth of a β-thal major (β-TM) child. This has important implications in prenatal diagnosis.</p> </abstract>