Case study: haemoglobin rothschild in a case presenting with cyanosis

Abstract

Introduction Here we describe a case presenting with episodic cyanosis in the absence of any evidence of cardio-pulmonary disease. Case The patient was a 27-year-old female who sought medical attention for a productive cough. On examination she was cya-nosed but not in distress. Systematic examination, notably cardio-respiratory system, revealed no abnormalities. A positive family history of episodic cyanosis in one of the siblings, but not the parents, was obtained. Results The full blood count, renal and liver functions were essentially normal. A normal haptoglobin level effectively excluded haemolysis. The oxygen saturation at the time of examination was 87%. An abnormal band was noted on Hb electrophoresis confirm-ing the presence of an Hb variant. Gene sequencing revealed a cod 37 (Tryp>Arg) mutation in exon 2 of the beta-globin gene, identi-fied as Hb Rothschild. Discussion Tryptophan at β37 is recognised as an important α1β2 contact point of the haemoglobin molecule. Disruption of the β37 contact point favours a T-quaternary (low oxygen affinity) state of the haemoglobin tetramer. Premature oxygen off-loading decreases the percentage oxygen saturation and may lead to cyanosis. Causes of cyanosis include cardio-respiratory disease, meth-aemoglobinaemia, sulfhaemoglobinaemia and low oxygen affinity haemoglobin variants.