• haemoglobinopathy
• haemolytic anaemia
• molecular genetics

Unstable haemoglobinopathies are rare autosomal dominant disorders that lead to haemolytic anaemia with varied severity. Structural defects in globin chains result in instability of the haemoglobin (Hb) tetramer with decreased solubility and intraerythrocytic precipitation (Heinz bodies). Clinically, unstable Hbs may remain undiagnosed either due to asymptomatic/milder phenotypes or may be misdiagnosed due to masquerading of other phenotypes. Laboratory identification depends on Hb high-performance liquid chromatography (HPLC), Hb electrophoresis, presence of Heinz bodies and heat and isopropanol stability tests.1 We report a child with de novo inheritance of Hb Sabine where the initial Hb HPLC was misleading.

A 4-year-old boy presented to the paediatric gastroenterology services with a history of progressive severe anaemia, high-coloured urine, waxing-and-waning jaundice, and abdominal distention for the last 2 years. In the past, he had been treated for viral hepatitis at 2 years of age and had an atypical febrile seizure at age 2.5 years. He had required 2 units of blood transfusion once, a year back. The boy was the fifth of six children. All siblings were asymptomatic and there was no family history of severe anaemia. Physical examination revealed growth retardation with a weight of 13 kg (<3rd percentile), height 91 cm (<3rd percentile), periorbital puffiness, haemolytic facies, hyperpigmented knuckles and hepatosplenomegaly (liver 5 cm and spleen 5 cm below respective costal margins).

Investigations revealed an Hb of 76 g/L, a mean corpuscular volume of 104.7 fL, a mean corpuscular Hb of 29.8 pg, a mean corpuscular Hb concentration of 28.5 g/L, red blood cells of 2.5 million/µL and red cell distribution width coefficient of variation of 35.3%. The peripheral smear showed many spherocytes with bite cells and polychromasia (figure 1A), and reticulocyte count (figure 1B) was markedly elevated (23%). Supravital staining with new methylene …