To our knowledge, this is the first attempt to report on the possible
genetic associations between delusional disorder and
paranoid schizophrenia on the basis of HLA genetic studies.
We found a significant association between delusional disorder
and the HLA-A*03 allele. When we measured the
strength of the association by the cross-product ratio or RR of
developing a disease, A*03 showed a very high value (RR
8.5) reflecting a strong positive association. However, we also
observed a strong association between HLA-A*03 and paranoid
schizophrenia. When we measured the strength of this
association by the same method, the A*03 gene again showed
a high value (RR 6.14).Wealso observed a moderately strong
association of the HLA-A*11 allele with paranoid schizophrenia,
coinciding with Alexander and colleagues’ findings (34).
Unlike some previous studies, however, we found no association
with either HLA-A23 or A24 in our patient group. Several
HLA-A and HLA-B haplotypes became significant in both
groups of patients, as well as in control subjects, but they were
extremely heterogeneous in nature. Only the A*02–B*07
haplotype was common in all subjects, except for healthy control
subjects matched with the paranoid schizophrenia group.
According to these findings, we cannot assign any particular
haplotype to the disease phenotype.