From a PLT volume, GWAS variant at rs10914144 in the DNM3 locus to the discovery of the functional variant rs2038479 at a MEIS1/RUNX1 binding site. A schema depicting the transcription of the DNM3 gene at 1q24.3 in CD34+ hematopoietic stem cells (top panel) and in MKs (bottom panel), respectively. A GWAS identified variant rs10914144 in intron 2 as being associated with differences in MPV. The MPV of persons homozygous for the major (C) allele of the variant is higher compared with the values observed in persons who are homozygous for the minor (T) allele. Functional annotation of the genome of megakaryocytic cells identified binding sites for the transcription factor MEIS1 in intron 2 at a position of an alternative transcription start site, which is uniquely used in MKs. The same element harbors SNP rs2038479, which is in high linkage disequilibrium with the GWAS sentinel rs10914144. DNM3 transcript levels (represented by the sizes of arrows at the consensus and alternative promoters) in PLTs from persons homozygous major (T) for rs2038479 were significantly lower than in PLTs from homozygous minor ones (C).