AIM: Stress peptide, pituitary adenylate cyclase activating polypeptide (PACAP), has been implicated in sudden infant death syndrome (SIDS). The aim of this exploratory study was to determine whether variants in the gene encoding the PACAP-specific receptor, PAC1, are associated with SIDS in Caucasian and African-American infants. METHODS: Polymerase chain reaction and Sanger DNA sequencing was used to compare variants in the 5'-untranslated region, exons and intron-exon boundaries of the PAC1 gene in 96 SIDS cases and 96 race- and gender-matched controls. RESULTS: The intron 3 variant, A/G: rs758995 (variant 'h'), and the intron 6 variant, C/T: rs10081254 (variant 'n'), were significantly associated with SIDS in Caucasians and African-Americans, respectively (p<0.05). Also associated with SIDS were interactions between the variants rs2302475 (variant 'i') in PAC1 and rs8192597 and rs2856966 in PACAP among Caucasians (p<0.02) and rs2267734 (variant 'q') in PAC1 and rs1893154 in PACAP among African-Americans (p<0.01). However none of these differences survived post hoc analysis. CONCLUSIONS: Overall, this study does not support a strong association between variants in the PAC1 gene and SIDS, however, a number of potential associations between race-specific variants and SIDS were identified that warrant targeted investigations in future studies. Keywords: genetic variants, PAC1 receptor, pituitary adenylate cyclase activating polypeptide, sudden infant death syndrome This article is protected by copyright. All rights reserved.