The BTB (Broad-Complex, Tramtrack and Bric a brac) domain, also known as the POZ (Poxvirus and Zinc finger) domain, is an N-terminal homodimerization domain that contains multiple copies of kelch repeats and/or C2H2-type zinc fingers. Proteins that contain BTB domains are thought to be involved in transcriptional regulation via control of chromatin structure and function. The Kelch domain-containing protein 7B (KLHDC7B) contains 5 Kelch repeats suggesting a role in transcription regulation. The gene encoding KLHDC6 maps to chromosome 22, which contains over 500 genes. As the second smallest human chromosome, 22 contains a surprising variety of interesting genes, including Phelan-McDermid syndrome, neurofibromatosis type 2 and autism.