Homozygosity for the p.Glu391Lys variation in the ENT1 nucleoside transporter is responsible for the At(a−) blood type in people of African ancestry. (A) Western blot analysis of ENT1 (performed as in Figure 1D) in an At(a−) subject and an At(a+) control, showing the presence of ENT1 in individuals with the At(a−) blood type. (B) Detail of SLC29A1 sequencing in an At(a−) subject and an At(a+) control, showing the homozygosity for the A allele of rs45458701 in individuals with the At(a−) blood type. Reference sequence (NC_000006) is indicated at the top, and the Taqα1 restriction site that is absent in the A allele but present in the G allele is underlined. (C) Topology diagram of the human ENT1 nucleoside transporter (adapted from Sundaram et al18 ) highlighting the location of the p.Glu391Lys variation encoded by the A allele of rs45458701; transmembrane domains are numbered 1 to 11. (D) Pedigree of the family of an At(a−) patient (arrow); gray- and white-filled symbols represent individuals with the At(a−) and At(a+) blood types, respectively; N/D, no data. (E) Polymerase chain reaction-restriction fragment length polymorphism analysis of rs45458701 in At(a−) and At(a+) controls (lanes 1 and 2) and in the family depicted in D (lanes 3-5).
