This is a highly significant difference that demonstrates that the psoriasis phenotype is genetically heterogeneous, but these results also provide two other insights: (i) that a subset of PsA patients are indeed genetically related to cutaneous psoriasis, since the frequency of this allele is 17–19% in the matched general population, and (ii) that PsA is genetically heterogeneous since 70% of PsA patients lack this susceptibility allele.
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