MXRA8 is a 442 amino acid single-pass type I membrane protein that is implicated in the maintenance and maturation of the blood-brain barrier. Containing two Ig-like V-type (immunoglobulin-like) domains, MXRA8 exists as two alternatively spliced isoforms that are encoded by a gene that maps to human chromosome 1p36.33. Human chromosome 1 spans 260 million base pairs, contains over 3,000 genes and comprises nearly 8% of the human genome. Chromosome 1 houses a large number of disease-associated genes, including those that are involved in familial adenomatous polyposis, Stickler syndrome, Parkinsons disease, Gaucher disease, schizophrenia and Usher syndrome. Aberrations in chromosome 1 are found in a variety of cancers, including head and neck cancer, malignant melanoma and multiple myeloma.