The ^Mγ chain of human fetal hemoglobin; its identification and occurrence

High-performance liquid chromatographic procedures have been used in the detection and identification of a new γ chain of human fetal hemoglobin (Hb). This ^Mγ chain is characterized by a Leu → Met replacement at position γ141; no other structural variations have been observed. The ^Mγ chain has been detected in red cell lysates of subjects with a heterozygosity for one of many types of so-called hereditary persistence of fetal hemoglobin conditions, which are characterized by an increased level of HB F in adult life, in sickle cell anemia, and in a few cord blood samples. At present it is not possible to definitely identify the genetic cause of this newly discovered heterogeneity; an infidelity in translation or the existence of an unrecognized γ globin gene should be considered.