Homozygosity for HBA1: c.179G > A: Hb Adana in an Infant

Abstract

Hb Adana (HBA1: c.179G > A) is a very rare, unstable form of α-globin variant that results from deficient synthesis of functional α chains. We present a 2-month-old boy with hypochromic microcytic anemia, and remarkable anisocytosis, target cells and basophilic stippling on his peripheral blood smear. α-Globin gene analysis of the patient determined homozygosity for HBA1: c.179G > A, a mutation known as Hb Adana. On his follow-up visit, hemoglobin (Hb) levels were stable at 9.0–9.5 g/dL and mean corpuscular volume (MCV) was 62.2–62.5 fL without the need for a blood transfusion. Clinical and hematological findings of our case were comparable to Hb H (β4) or β-thalassemia intermedia (β-TI)-like phenotypes, despite the fact that he carried an α1 gene mutation. Heterozygosity for the HBA1: c.179G > A mutation may also lead to microcytosis only as seen in his parents. According to our current knowledge, this is the first described case with homozygosity for the Hb Adana mutation, carried on the α1 gene. The relatively mild presentation of the case highlights the milder phenotypic consequences of nondeletional α mutations in the α1 vs. the α2 gene.