ARL17A and Alzheimer disease: Searching for additional examples of multiple variants functional relations, we studied GWAS variants associated to Alzheimer's disease and showed that absence of risk alleles for variants rs199499 and rs7207400 is necessary to sustain the transcript level of several genes (LRRC37A, LRRC37A2 and ARL17A) in the complex genomic region 17q21.31.