A4GALT and transcript variants. (A) Schematic presentation of A4GALT at the top with the 3 previously known exons (in black) and a novel exon (here designated exon 2a in gray). The GenBank accession no. NC_00022.10 sequence was used to calculate exon and intron sizes indicated below or above their respective symbols. Four different transcript variants (designated I-IV with previously known exons in white and the new exon 2a in gray) were found in the Ramos cell line, and the actual exon size according to sequencing is given below each white box. Transcript IV was also found in cultured primary human bone marrow cells. (B) The new transcript is shown with exon 1 in white and exon 2a in gray. It includes 1 polymorphism specific for P¹/P² (ACG versus ATG, in which the SNP is highlighted in bold) and 2 unspecific polymorphisms (indicated by asterisks). In P², the specific polymorphism gives rise to an ORF (hatched) with the potential to be translated into a 28-amino acid peptide.