Allele- and genotype frequencies for the polymerase chain reaction-based DNA genetic marker HLA-DQA1 were determined previously in a Swiss sample population (n=200). In this study we subtyped the allele 4 in the same Swiss Caucasian population sample (distinguishing the 4.1 allele from the 4.2 and 4.3 alleles) using the AmpliType PM + DQA1 PCR Amplification and Typing Kit. No deviations from Hardy-Weinberg equilibrium could be observed. The power of discrimination (Pd) of the HLA-DQA1 locus without subtyping the 4 allele for Swiss Caucasians was 0.931, when subtyping the 4 allele the value is 0.938. The frequency data can be used in forensic analyses to estimate the frequency of a HLA-DQA1 profile in the Swiss population.