First report of an Asian family with hemoglobin Evans [α2 62 (E11) Val → Met]

Abstract

Hemoglobin Evans is an unstable variant caused by a single nucleotide mutation that produces a valine-to-methionine substitution at residue 62 of the α-globin chain. It has not been reported in the Asian population and only three cases have been reported worldwide. We diagnosed a Japanese boy with chronic hemolytic anemia with hemoglobin Evans after genetic testing. This is the first familial case of hemoglobin Evans in an Asian population.

Choledocholithiases in a child with Hemoglobin Evans [alpha2 62(E11) Val→Met]

“…Hemoglobin Evans is a rare, inherited, unstable hemoglobin variant . Only several lineages have ever been reported worldwide .…”

“…Hemoglobin Evans is a rare, inherited, unstable hemoglobin variant . Only several lineages have ever been reported worldwide . Patients who are heterozygous for this rare in‐frame mutation suffer several complications, including mild hemolytic anemia, splenomegaly, and aplastic crisis , but biliary stones have hitherto never been reported.…”

The first reported use of red blood cell exchange to treat hemoglobin Evans with secondary methemoglobinemia

“…This unstable hemoglobin is due to a valine-to-methionine substitution at position 62 (E11) of the α2-globin chain (HGVS:HBA2: c.187G > A). 4 Biochemically, this mutation in the heme contact site leads to instability in the molecule, loss of solubility, and precipitation in the red blood cell (RBC), leading to premature erythrocyte destruction. Similar to β variants affecting the corresponding E11 helical position at β67, such as Hb M-Milwaukee-I (β67[E11] Val > Glu) (HGVS: HBBc.203 T > A), Hb Evans can be associated with the formation of methemoglobin.…”

“…1,6 Most patients come to medical attention due to severe, unexplained hemolytic anemia or due to secondary manifestations, such as cholelithiasis. 1,4,5,7 The severity of clinical symptoms varies from mild to severe. Most patients require no treatment, while others require chronic transfusions and even splenectomy in early life.…”

“…In this manuscript, we report the case of a 60‐year‐old male with a long‐term history of hemoglobin Evans (Hb Evans). This unstable hemoglobin is due to a valine‐to‐methionine substitution at position 62 (E11) of the α2‐globin chain (HGVS:HBA2:c.187G > A) 4 …”