Variants per miRNA region. (A) The different colored circles on the world map indicate the geographic location of the 14 sampled populations. Populations from Africa are shown in red (Pygmy, Hadza, Sandawe, Yoruba, Luhya, and Maasai), Asian populations in green (Gujarati Indians, Japanese, and Han Chinese), European populations in blue (Toscani Italians, Utah residents with Northern European ancestry), and recently admixed populations in stripes (African-Americans, Mexican-Americans and Puerto Ricans) (See Methods). Representative regions are enclosed by the thick black lines (B) The top panel shows the human miRNA hairpin, hsa-mir-302d, displayed in its modified form with a novel SNP found in its seed sequence circled in black. Seed sequences are defined as the 2nd -8th base of the 5’ end of mature double-stranded miRNA. The mature sequence is highlighted with the guide strand shown in red and the passenger strand shown in blue. The bottom panel depicts the summary of allele types in miRNA genes including novel and non-singleton alleles. Here, mature sequences (green) are defined as all bases within the mature miRNA excluding those within the seed sequence (red). Consistently, stem loops (blue) are defined as all bases excluded from the mature and seed sequences but included in the pre-miRNA hairpin (grey).