The SOX18 gene codes for a member of the SRY related HMG Box (SOX) family of transcription factors. These transcription factors are known to play a major role in the regulation of embryonic development. Sox18, specifically, was shown to be involved in lymphangiogenesis and angiogenesis, cardiovascular development, and hair follicle formation. Sox18 carries out its transcriptional activities in a complex, which consists of several other transcription factors, including two other members of the SOXF family, Sox7 and Sox17. Within the genome, Sox18 binds to a specific sequence, called the Sox consensus motif with a core sequence of AACAAAG.
Mutations in SOX18 cause a disorder known as Hypotrichosis -Lymphedema- Telangiectasia Syndrome (HLTS). Overexpression of Sox18 has also been seen in a variety of different kinds of cancers.