Figure 3.

Illustration of the first recommendation for a common mutation nomenclature. Example annotation for parts of gene MECP2 (GenBank entry: NG_007107.1) using the first suggestions for a mutation nomenclature. Exonic sequence is labeled green, intronic regions are labeled brown and the surrounding untranslated regions are labeled in blue. In the first suggestions for a common nomenclature the most 5’ sequence of the first exon is the start position. Adjacent bases are subsequently numbered. Variations occurring in intronic regions obtain two numbers. The first describes the location of the closest exon and the second is the distance to this exons. As shown in this picture, intronic positions are usually described in relation to the closer exon. The underlined ATG marks the start codon, where the leading adenine has been later proposed as common start position. Using these recommendations the two SNPs are described as 2C→A and 252+2T→C