Hb Dhonburi (Neapolis) [β126(H4)Val→Gly] Identified in a Family from Northern Iran

Abstract

Thalassemias are the most common hereditary diseases in Iran, resulting from synthesis defects in one or more hemoglobin (Hb) subunits. The majority of patients suffer from β‐thalassemia (thal), but cases with microcytic hypochromic anemia and normal electrophoretic patterns are suspected to have α‐ or silent β‐thal. A family from the northern part of Iran, an area highly prevalent for thalassemias, was referred to us for prenatal diagnosis. The hematological data of the father indicated a pattern of β‐thal minor. Reverse hybridization analysis for the most common β‐globin mutations identified IVS‐II‐1 (G→A) in the heterozygous state. The maternal laboratory data indicated a case more compatible with α‐thal. Iron deficient anemia was ruled out, and common α‐thal point mutations and deletions were investigated. As no mutation was detected, chain synthesis was performed and showed an α/β chain ratio of 2.1, that was in the range of β‐thal minor. DNA sequencing of the entire β‐globin gene identified a heterozygous GTG→GGG (Val→Gly) mutation at codon 126, also known as Hb Dhonburi (Neapolis). Prenatal diagnosis of the fetal DNA showed the absence of the IVS‐II‐1 and codon 126 anomalies. This result demonstrates the importance of screening of individuals with mild microcytic hypochromic anemia for both α‐ and silent β‐thal mutations.

• Thalassemia
• Hb Dhonburi (Neapolis)
• Iran