SH2D4B (SH2 domain containing 4B) is a 431 amino acid protein that contains one SH2 domain, exists as three alternatively spliced isoforms and is encoded by a gene that maps to human chromosome 10q23.1. Spanning nearly 135 million base pairs, chromosome 10 makes up approximately 4.5% of total DNA in cells and encodes nearly 1,200 genes. Several protein-coding genes, including those that encode for chemokines, cadherins, excision repair proteins, early growth response factors (Egrs) and fibroblast growth receptors (FGFRs), are located on chromosome 10. Defects in some of the genes that map to chromosome 10 are associated with Charcot-Marie Tooth disease, Jackson-Weiss syndrome, Usher syndrome, nonsyndromatic deafness, Wolman’s syndrome, Cowden syndrome, multiple endocrine neoplasia type 2 and porphyria.