SYAP1 (synapse-associated protein 1) is a 352 amino acid protein that is ubiquitously expressed in adult tissues. SYAP1 contains one BSD domain which is a novel domain that is present in basal transcription factors, synapse-associated proteins and several hypothetical proteins. The BSD domain is characterized by three predicted alpha helices and by conserved tryptophan and phenylalanine residues, located at the C-terminus of the domain. The gene that encodes SYAP1 in humans is located on chromosome X. Chromosome X consists of about 153 million base pairs and nearly 1,000 genes. Color blindness, hemophilia, and Duchenne muscular dystrophy are well known X chromosome-linked conditions which affect males more frequently as males carry a single X chromosome.