Prevalence and Genetic Analysis of α- and β-Thalassemia and Sickle Cell Anemia in Southwest Iran

Forozan H Nezhad,Khojasteh H Nezhad,Parastoo M Choghakabodi,Bijan Keikhaei

doi:10.2991/j.jegh.2018.04.103

Abstract

This prospective study assessed the prevalence and genetic analysis of α- and β-thalassemia and sickle cell anemia (SCA) in Southwest Iran. Hematological indices were measured in 17,581 couples living in Khuzestan Province, Southwest Iran. Individuals with mean corpuscular volume <80, mean corpuscular hemoglobin <27, hemoglobin A2 ≥3/5 were considered as β-thalassemia traits. Prevalence of minor β-thalassemia, α-thalassemia, SCA, iron deficiency anemia, and silent thalassemia were respectively identified in 995 (5.6%), 1169 (6.65%), 1240 (7.05%), 911 (5.18%), and 1134 (6.45%) individuals using a multiplex amplification refractory mutation system, and direct DNA sequencing of globin genes. Three codons IVS-II-1 (G → A; 26%; n = 13), IVS-I-1 (G → T; 16%; n = 8), and IVS-I-110 (G → A; 14%; n = 7) were the most frequent mutants and IVS-II-1 was the most common β-thalassemia mutation. Also, based on a gap-polymerase chain reaction assay, genotype frequencies of α -globin mutations were –α3.7kb (50%; n = 25), Med/ααthal (12%; n = 6), and –α 4.2/αα (10%; n = 5), which were the most frequent deletion mutants (72% in total). The most common deletion (50%) was –αα3.7kb. Our data suggest that the population of Southwest Iran is at high risk of α- and β-thalassemia caused by these deletion mutants and SCA. Our findings will be useful for developing an efficient control program and genetic counseling.

Highlights

Thalassemia is a genetic abnormality involving mutations of the genes responsible for hemoglobin production in the blood
4.5 of every 10,000 live births throughout the world are affected by thalassemia. a-Thalassemia is more frequent in Southeast Asia than in other areas of the world, and up to 40% of genetic traits have been found in thalassemia traits (TTs) (1–30%)
In a molecular study of 50 individuals (5%) randomly selected using multiplex amplification refractory mutation system (M-ARMS), eight codons from the b-globin defects accounted for 90% of the total b-thalassemia mutations: IVSII-1 (G → A; 26%; n = 13), IVS-I-1 (G → T; 16%; n = 8), IVS-I

Summary

Introduction

Thalassemia is a genetic abnormality involving mutations of the genes responsible for hemoglobin production in the blood. A-Thalassemia is more frequent in Southeast Asia than in other areas of the world, and up to 40% of genetic traits have been found in thalassemia traits (TTs) (1–30%). People living in the Mediterranean, African, and South Asian areas are more likely to be affected by b -thalassemia. Genetic prevalence of b -thalassemia throughout the world is 2–18% (affected by a gene mutation) in the Eastern Mediterranean and 0–11% in Southeast Asia [1]. 5% of the global population have a variation in the a or b part of the hemoglobin molecule, some of these are asymptomatic and known as silent traits. Only 1.7% of the global population have signs as a result of the gene mutations, known as a-TT. Tribal or ethnic groups are more likely to be affected and 5–30% of the population may be symptomatic among these groups [1]

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