We found in the Ca2+ channel alpha1C subunit gene a new repetitive element of three paired exon 45/46-related sequences. We also identified a new exon 45/46-related sequence in the human genome and mapped it by fluorescence in situ hybridization to the 12p11.2 and 12p13.2-p13.1 bands. These positions are not recognized by DNA probes generated from the 5'- and 3'-terminal regions of the alpha1C gene. A possible existence of a new genomic homologue of the alpha1C subunit gene is discussed.