Loss of heterozygosity (LOH) on chromosome 1 in patients with spontaneous Rh phenotype splitting. (A) Myeloid lineage–restricted LOH on chromosome 1. Representative electropherograms of the D1S2697 and D1S2864 microsatellite markers with DNA samples from blood, different tissues, and sorted blood cell subsets of patient 1 and 3, respectively, are shown. Note pronounced peak imbalance in blood, and apparent LOH in myeloid cell subsets. Similar results were obtained with samples of patients 1, 2, and 9 and further microsatellite markers (as indicated by ‡ in Table 3). (B) LOH on chromosome 1 in RHD⁻/RHCE*C⁻ (only RHCE*c⁺/RHCE*e⁺) but not in RHD⁺/RHCE*C⁺ (and additionally RHCE*c⁺/RHCE*e⁺) erythropoietic blast-forming units (BFU-Es). Representative electropherograms of the D1S233 and D1S199 microsatellite markers with DNA samples from blood and single BFU-Es of patient 2 and 6, respectively, are shown. Similar observations were made with samples of patients 2, 3, and 6 and with other microsatellite markers (all markers showing LOH as given in Table 5). Peak heights represent fluorescence intensity; numbers denote relative fragment size (bp).