Haemoglobin C Harlem

Haemoglobin C Harlem  is a variant haemoglobin that moves like Hb C in standard electrophoresis at alkaline pH and occupies the position of Hb S at acidic pH (agar gel). It is due to 2 amino acids substitutions in the same beta globin chain [beta6 Glu->Val + beta73 Asp->Asn]. The first substitution (beta6 Glu->Val) is characteristic of Hb S (sickle Hb) while the second replacement (beta73 Asp->Asn) is found in haemoglobin variant, Hb Korle-Bu. Hb C-Harlem is less stable than Hb A and Hb S. It produces red cells sickling when deoxygenated. All haematological parameters are normal in the heterozygote, with 40-44% of the variant Hb in standard electrophoresis. When found together with Hb S the condition resembles sickle cell anaemia. This haemoglobin has been found in several African families.

Synonym: HB C Harlem