The first example of a deletion in the human alpha chain: hemoglobin Boyle Heights or alpha 2 6 (A4) Asp----to O beta 2.

Hemoglobin Boyle Heights (alpha 6 (A4) Asp leads to O) is the first observed variant with a deletion in the alpha chain. The variant, which was detected in a 39-year-old man of Mexican descent, constitutes 14% of the total hemoglobin and is associated with microcytosis, heat instability, and increased oxygen affinity. It migrates between Hb F and Hb S on cellulose acetate and starch gel electrophoresis and with Hb A on citrate agar gel electrophoresis. Identification was done by high performance liquid chromatographic procedures. Residue Asp alpha 6 is neither a heme nor an interchain contact, but does have intrachain contacts. Like Hb Sawara (alpha 6 Asp leads to Ala), Hb Boyle Heights has increased oxygen affinity. It is likely that the Bohr effect will be altered because the deletion in Hb Boyle Heights should alter the configuration of Val alpha 1 and influence its participation in the Bohr effect.