The NACP/synuclein gene: chromosomal assignment and screening for alterations in Alzheimer disease.

The major component of the vascular and plaque amyloid deposits in Alzheimer disease is the amyloid beta peptide (A beta). A second intrinsic component of amyloid, the NAC (non-A beta component of amyloid) peptide, has recently been identified, and its precursor protein was named NACP. A computer homology search allowed us to establish that the human NACP gene was homologous to the rat synuclein gene. We mapped the NACP/synuclein gene to chromosome 4 and cloned three alternatively spliced transcripts in lymphocytes derived from a normal subject. We analyzed by RT-PCR and direct sequencing the entire coding region of the NACP/synuclein gene in a group of patients with familial early onset Alzheimer disease. No mutation was found in 26 unrelated patients. Further studies are required to investigate the implication of the NACP/synuclein gene in Alzheimer disease.