Later, it was found that the strongest HLA associations included class II alleles, suggesting a major role of CD4 T-cells; among 43 patients of Caucasian-origin with PCD, DQA1*03:03-DRB1*04:01 showed a protective effect (0% vs. less than 20% in control group; p < 0.05, OR = 0), but no risk haplotype was found to be shared by all patients [29]. This evidence concerns the gene CD4 and paraneoplastic neurologic syndrome.