Day 138 has 45 protein-coding genes (browser view). It includes a gene-poor region 6q22.1 which used to be a centromere 17 million years ago.
Centromeres can often move around in humans without any harmful changes. This 6q22.1 neocentromere was discovered by chance by Cappozi et al. in a family when taking a karyotype, and through analysis of other primates was inferred to have been a centromere earlier in evolutionary history.
Click here to see all 8540299 letters of Day 138.