Generation and annotation of the DNA sequences of human chromosomes 2 and 4

Human chromosome 2 is unique to the human lineage in being the product of a head-to-head fusion of two intermediate-sized ancestral chromosomes. Chromosome 4 has received attention primarily related to the search for the Huntington's disease gene, but also for genes associated with Wolf-Hirschhorn syndrome, polycystic kidney disease and a form of muscular dystrophy. Here we present approximately 237 million base pairs of sequence for chromosome 2, and 186 million base pairs for chromosome 4, representing more than 99.6% of their euchromatic sequences. Our initial analyses have identified 1,346 protein-coding genes and 1,239 pseudogenes on chromosome 2, and 796 protein-coding genes and 778 pseudogenes on chromosome 4. Extensive analyses confirm the underlying construction of the sequence, and expand our understanding of the structure and evolution of mammalian chromosomes, including gene deserts, segmental duplications and highly variant regions. Two into 2 will go The comprehensive annotated sequences of human chromosomes 2 and 4 are published this week. Together, they represent 5% of the estimated size of the human genome; chromosome 2 contains the largest amount of genetically active DNA sequence of any human chromosome. Chromosome 2 is of particular interest in terms of human evolution, as it is the product of head-to-head fusion of two ancestral chromosomes after the separation of the human and chimpanzee lineages.