Abstract
Structural analyses of an abnormal y` chain, present in a relative amount of ∼10% in a cord blood sample of a Black newborn baby, identified two substitutions (γ75 lle←Thr and γ136 Ala←Gly) in an apparent variant of the Aγ chain. Gene mapping analysis of genomic DNA and hybridization with specific probes confirmed the presence of these two mutations and provided the evidence to indicate that the abnormal γ chain was indeed a variant ofAγ with the two listed mutations.