The subject sample mapping data table contains a mapping of study subject IDs to sample IDs and sample use. dbGaP samples are defined as the final preps submitted for genotyping, sequencing, and/or expression data. For example, if one patient (subject ID) gave one sample, and that sample was processed differently to generate 2 sequencing runs, there would be two rows, both using the same subject ID, but having 2 unique sample IDs.