Day 289 has 75 protein-coding genes (browser view) including the IGH@ locus.
This is a place where B and T cells shuffle their genes, along with Day 40 (2p11.2-2p11.1): The IGK@ locus, an incredible card-shuffling act.
Click here to see all 8234133 letters of Day 289 with IGHG1 underlined.