The total number of hemoglobin (Hb) variants currently included in the globin gene server database is 1626 (November 12 2014), of which 131 are fetal Hb variants. These variants are observed as two different subunits of fetal Hb, (G)γ- and (A)γ-globin chains. Of the 131 documented fetal Hb variants, 73 are (G)γ- and 58 are (A)γ-globin chain variants. Although they are easily detected at birth, as the quantity of γ chains progressively decreases over the first few months of life, they are essentially undetectable after 6 months of age. In this report we discuss the molecular characteristics and diagnostic criteria of a new (A)γ chain variant that was detected during newborn screening and named Hb F-Sykesville MD [(A)γ113(G15)Val → Ile; HBG1: c.340G>A].
Keywords: Aγ-Globin chain; Hb F-Sykesville MD; new variant; newborn.