Distribution of PKLR mutations associated with PK deficiency. Schematic representation of the PKLR gene and its erythroid-specific promoter. Exons, but not introns, are drawn to scale. Exons are numbered and depicted as orange rectangles with 5′ and 3′ noncoding sequences in dark orange. The white rectangle represents the liver-specific exon 2. Nucleotides are numbered starting from ATG in red blood cell-specific exon 1. The locations of the more than 160 mutations associated with PK deficiency⁹³  are indicated by vertical lines. Larger vertical lines represent multiple base changes at the same nucleotide position. The horizontal lines indicate the extent of the 3 large deletions known to date. Illustration enhanced by A. V. Chen.