s0080}
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Recent studies noted frequency differences in *PTEN* deletion between AA and CA CaP ([@bb0030], [@bb0120]). The virtual absence of *PTEN* deletion observed in AA CaP whole genome sequence data shown here was striking ([Fig. 1](#f0005){ref-type="fig"}b). To validate these observations in an independent set of samples, we probed the *PTEN* locus by FISH in a tissue microarray, as described above. *PTEN* deletions were notably less frequent in AA (15%) compared to CA cases (63%) (*p* = 1E-06), with even larger difference seen between Gleason 6 AA (7%) and CA (53%) tumors (*p* = 0.004) ([Table 2a](#t0015){ref-type="table"}, [Table 2b](#t0020){ref-type="table"}).

4. Discussion {#s0085}
=============

Emerging data from our and other groups support biological and genetic differences between African American (AA) and Caucasian American (CA) CaP. While reports on comprehensive evaluations of primary CaP genomes or exomes have highlighted recurrent alterations (*TMPRSS2-ERG*, *PTEN*, *SPOP and CHD1*), these studies were focused on patients with Caucasian ancestry. *ERG* oncogenic activation via gene fusions and deletion of the *PTEN* tumor suppressor are major early tumorigenic driver alterations in CaP genomes ([@bb0025], [@bb0160], [@bb0255]). Within the continuum of assessments of these alterations high frequencies in CA patients and lower frequencies in AA men were noted ([@bb0030], [@bb0075], [@bb0105], [@bb0120], [@bb0165], [@bb0190], [@bb0215]). In Asian subjects, CaP frequencies of *ERG* and *PTEN* alterations are the lowest ([@bb0030], [@bb0170], [@bb0205]). The goal of this study was to delineate genomic features of AA and CA CaP focusing on early stages of the disease representing majority of cases at initial presentation in Western countries.

 In summary, three recurrent genomic alterations (*PTEN*, *LSAMP* region and *ERG*) showed distinct prevalence between AA and CA CaP. This study discovered a nove