Association between HLA-A1 allele and schizophrenia gene(s) in patients refractory to conventional neuroleptics but responsive to clozapine medication.

We report an association between HLA-A1 allele and a subgroup of schizophrenic patients refractory to conventional neuroleptic treatment but responsive to clozapine. The frequency of HLA-A1 was 58% among the schizophrenic patients not responding to conventional treatment but responsive to clozapine but only 10.5% among the patients responding to conventional neuroleptics. The HLA-A1 occurs in 20% of the random Finnish population. Our results indicate that HLA-A1 defines a subgroup of schizophrenic patients with a selective response to neuroleptics.