BEND4 is a 530 amino acid protein that contains a BEN domain. BEND4 exists as five alternatively spiced isoforms and is considered a complete proteome. BEN domain mediates protein–DNA and protein–protein interactions during chromatin organization and transcription. BEN domain may play a role in organization of viral DNA during replication or transcription. The BEND4 gene maps to human chromosome 4p13. Representing approximately 6% of the human genome, chromosome 4 contains nearly 900 genes. Chromosome 4 reportedly contains the largest gene deserts (regions of the genome with no protein encoding genes) and has one of the two lowest recombination frequencies of the human chromosomes. Notably, the Huntingtin gene, which is found to encode an expanded glutamine tract in cases of Huntington's disease, is on chromosome 4. FGFR-3 is also encoded on chromosome 4 and has been associated with thanatophoric dwarfism, achondroplasia, Muenke syndrome and bladder cancer.