Acute hemolytic crises and clinical course in a Japanese family with Hb Santander: a detailed case report

A Japanese woman presented with a history of neonatal jaundice and recurrent episodes of severe fatigue and jaundice during viral infections in her late teens. Her mother, aunt, and grandmother had similar clinical histories. During an admission for fever and fatigue, blood tests revealed acute hemolysis and an abnormal hemoglobin band on high-performance liquid chromatography. β-globin gene sequencing identified a codon 34 substitution from GTC (Val) to GAC (Asp), confirming the presence of the unstable hemoglobin variant Hb Santander. This very rare hemoglobinopathy was previously reported only in a single sporadic case involving a Spanish man; this is the first documented case in a Japanese family. Our observation of four affected individuals across three generations provided insight into the progression of Hb Santander from birth to old age. Unstable hemoglobin variants can lead to recurrent, severe episodes of acute hemolytic crisis. Chronic hemolysis in the steady state was compensated without anemia or polycythemia but was associated with an increased risk of gallstone formation. Hb Santander does not appear to be a life-shortening hemoglobinopathy; however, clinical vigilance is necessary for acute hemolysis triggered by drugs or infections and for gallstones at a younger age, particularly in patients with Gilbert syndrome.