SNP-A identifies genomic regions with potential pathogenic significance in AA. We identified 2 overlapping regions of copy-neutral loss of heterozygosity (blue bars) on the short arm of chromosome 6 in patients with AA; a microdeletion at 6p22.1 (86 KB, green bar) in a third patient defined a minimally affected region (top). This region contained the HLA-A locus. The patient with the microdeletion (no. 48) was treated with immunosuppression. After immunosuppression, the lesion disappeared, confirming the somatic nature of the lesion.