HLA-C and schizophrenia: To further examine the role of the MHC region in axonal density, we calculated a schizophrenia PRS-like score based on the four SNPs within the extended MHC region that had been originally reported by the PGC3 [2] to have conditionally independent evidence for association with SZ (i.e., rs13195636, rs8192589, rs9461856, rs9368789).