BTNL8 is a 500 amino acid single-pass type I membrane protein that belongs to the immunoglobulin superfamily and contains one B30.2 SPRY domain and one Ig-like V-type (immunoglobulin-like) domain. Expressed as multiple alternatively spliced isoforms, BTNL8 is encoded by a gene which maps to human chromosome 5. With 181 million base pairs encoding around 1,000 genes, chromosome 5 comprises about 6% of human genomic DNA. Deletion of the p arm of chromosome 5 leads to Cri du chat syndrome, while deletion of the q arm on chromosome 5 is common in therapy-related acute myelogenous leukemias and myelodysplastic syndrome.