NGS of circulating tumor DNA (ctDNA; Specimen 3) using the FoundationOne Liquid CDx panel showed a ctDNA tumor fraction of 5.1% with estimated TMB 8 muts/Mb, microsatellite stable status, TMPRSS2-ERG fusion, pathogenic mutations in AR, CHEK2, NF1, PIK3CA, and TP53, and no alterations to MSH2 nor BRCA2. Notably, this test does not measure copy number alterations of MSH2 and its median limit of detection of BRCA2 copy number loss is a tumor fraction of 30.4%, according to the FDA-filed technical report. The gene discussed is ERG; the disease is neoplasm.