In addition, we have shown that in Caucasians the SNCA and MAPT genes act synergistically to influence the rate of progression of PD (certain genotypes have a 5.8-increased risk for developing a more rapid disease progression) when analysing one microsatellite (Rep1 or D4S3481 with three common alleles, that is, 259 bp, 261 bp, and 263 bp or alleles 0, 1, and 2) marker of SNCA gene and a rs17650901 SNP of MAPT gene (lies in exon 1 and its A-allele tags the MAPT H1 haplotype [15]) in an Australian cohort [7]. The gene discussed is MAPT; the disease is Parkinson disease.