HIT-40 is a 643 amino acid nuclear protein that belongs to the Krpel C2H2-type zinc-finger protein family. Containing eighteen C2H2-type zinc fingers and one KRAB domain, HIT-40 may be involved in transcriptional regulation. HIT-40 exists as two isoforms due to alternative splicing events, and is encoded by a gene that maps to human chromosome 19p13.2. Consisting of around 63 million bases with over 1,400 genes, chromosome 19 makes up over 2% of human genomic DNA and is recognized for having the greatest gene density of the human chromosomes. It is the genetic home for a number of immunoglobulin superfamily members including the killer cell and leukocyte Ig-like receptors, a number of ICAMs, the CEACAM and PSG families, and Fc?receptors. Peutz-Jeghers syndrome, spinocerebellar ataxia type 6, the stroke disorder CADASIL, hypercholesterolemia and insulin-dependent diabetes have been linked to chromosome 19.