You can explore DNA sequence close to ABCC4 transcription start site with http://www.ncbi.nlm.nih.gov/variation/view/ (mark "single nucleotide variant " to have only SNPs)
The colsest one I guess is http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ref.cgi?rs=386618045 though its not exactly on place. So better figure out the genome coordinates (BLAST part of the sequence around the SNP if you have it) than see if there is snp annotated for this coordinate. Take care to select correct genome assembly.