The variant fetal hemoglobin F Texas I is abnormally acetylated

Two related infants with indistinct slow‐moving minor hemoglobin bands were detected by electrophoretic cord blood screening. The variant separated into a major and a minor band on isoelectric focusing (IEF), anion exchange chromatography (AEC), and high‐performance liquid chromatography (HPLC). Analysis of the products of tryptic hydrolysis of the abnormal chain revealed a truncated AγT‐l peptide containing a glu→lys substitution at position 5, identifying the variant as Hb F Texas 1. Microsequencing of the major early peak from AEC confirmed the substitution. However, γ chains from the minor peak resisted Edman degradation and were shown to be acetylated by fast atom bombardment mass spectrometry (FABMS). Acetylation of HbF Texas I was nearly three times that of normal HbF measured in the same hemolysate, and this ratio remained constant for over 1 year in the proband. This represents the first demonstration of increased Nα‐acetylation of a variant fetal hemoglobin.