Day 155 has 30 protein-coding genes (browser view), and overlaps with the region where genes are deleted in Williams syndrome.
From Chris Murgatroyd’s Power of the Gene:
Williams syndrome, affecting in around 1 in 20,000 people, in which a piece of DNA containing a number of genes is lost, leading to cardiovascular problems and a generally low IQ. However, these individuals tend to show competence in areas such as language and music, with many showing a near perfect music pitch and an uncanny sense of rhythm. People with William’s syndrome also have characteristic ‘elfin-like’ facial features with a small upturned nose, depressed nasal bridge and a broad mouth with full lips. This, together with their often-remarkable musical and verbal abilities, and highly sociable depositions, has lead to the suggestion that affected children were the inspiration for folktales and legends such as pixies, elves and fairies, which were often musicians and storytellers.
Click here to see all 8386630 letters of Day 155.