Transcriptomic profiling and genomic rearrangement landscape of Nigerian prostate cancer.

BACKGROUND: Men of African ancestry have disproportionately high incidence rates of prostate cancer (PCa) and have high mortality rates. While there is evidence for a higher genetic predisposition for incidence of PCa in men of African ancestry compared to men of European ancestry, there have been few transcriptomic studies on PCa in men of African ancestry in the African continent. OBJECTIVE: We performed transcriptomic profiling and fusion analysis on bulk RNA sequencing (RNA-seq) samples from 24 Nigerian PCa patients to investigate the transcriptomic and genomic rearrangement landscape of PCa in Nigerian men. DESIGN: Bulk RNA-seq was performed on 24 formalin-fixed paraffin-embeded (FFPE) prostatectomy specimens of Nigerian men. Transcriptomic analysis was performed on 11 high-quality samples. Arriba Fusion and STAR Fusion were used for fusion detection. RESULTS: 4/11 (36%) of the samples harbored an erythroblast transformation-specific (ETS) fusion event; 1/11 (9%) had a TMPRSS2-ERG fusion; 2/11 had a TMPRSS2-ETV5 fusion, and 1/11 had a SLC45A3-SKIL fusion. Hierarchical clustering of normalized and mean-centered gene expression showed clustering of fusion positive samples. Furthermore, we developed gene set signatures for Nigerian PCa based on fusion events. By projecting the cancer genome atlas prostate adenocarcinoma (TCGA-PRAD) bulk RNA-seq data set onto the transcriptional space defined by these signatures derived from Nigerian PCa patients, we identified a positive correlation between the Nigerian fusion signature and fusion positive samples in the TCGA-PRAD data set. CONCLUSIONS: Less frequent ETS fusion events other than TMPRSS2-ERG such as TMPRSS2-ETV5 and non-ETS fusion events such as SLC45A3-SKIL may be more common in PCa in Nigerian men. This study provides useful working transcriptomic signatures that characterize oncogenic states representative of specific gene fusion events in PCa from Nigerian men.

Genetic ancestry and diagnostic yield of exome sequencing in a diverse population.

It has been suggested that diagnostic yield (DY) from Exome Sequencing (ES) may be lower among patients with non-European ancestries than those with European ancestry. We examined the association of DY with estimated continental/subcontinental genetic ancestry in a racially/ethnically diverse pediatric and prenatal clinical cohort. Cases (N = 845) with suspected genetic disorders underwent ES for diagnosis. Continental/subcontinental genetic ancestry proportions were estimated from the ES data. We compared the distribution of genetic ancestries in positive, negative, and inconclusive cases by Kolmogorov-Smirnov tests and linear associations of ancestry with DY by Cochran-Armitage trend tests. We observed no reduction in overall DY associated with any genetic ancestry (African, Native American, East Asian, European, Middle Eastern, South Asian). However, we observed a relative increase in proportion of autosomal recessive homozygous inheritance versus other inheritance patterns associated with Middle Eastern and South Asian ancestry, due to consanguinity. In this empirical study of ES for undiagnosed pediatric and prenatal genetic conditions, genetic ancestry was not associated with the likelihood of a positive diagnosis, supporting the equitable use of ES in diagnosis of previously undiagnosed but potentially Mendelian disorders across all ancestral populations.

Diagnostic Yield of Exome Sequencing in a Diverse Pediatric and Prenatal Population is not Associated with Genetic Ancestry.

Purpose: It has been hypothesized that diagnostic yield (DY) from Exome Sequencing (ES) may be lower among patients with non-European ancestries than those with European ancestry. We examined the association of DY with estimated continental genetic ancestry in a racially/ethnically diverse pediatric and prenatal clinical cohort. Methods: Cases (N=845) with suspected genetic disorders underwent ES for diagnosis. Continental genetic ancestry proportions were estimated from the ES data. We compared the distribution of genetic ancestries in positive, negative, and inconclusive cases by Kolmogorov Smirnov tests and linear associations of ancestry with DY by Cochran-Armitage trend tests. Results: We observed no reduction in overall DY associated with any continental genetic ancestry (Africa, America, East Asia, Europe, Middle East, South Asia). However, we observed a relative increase in proportion of autosomal recessive homozygous inheritance versus other inheritance patterns associated with Middle Eastern and South Asian ancestry, due to consanguinity. Conclusions: In this empirical study of ES for undiagnosed pediatric and prenatal genetic conditions, genetic ancestry was not associated with the likelihood of a positive diagnosis, supporting the ethical and equitable use of ES in diagnosis of previously undiagnosed but potentially Mendelian disorders across all ancestral populations.

Diagnostic yield of pediatric and prenatal exome sequencing in a diverse population.

The diagnostic yield of exome sequencing (ES) has primarily been evaluated in individuals of European ancestry, with less focus on underrepresented minority (URM) and underserved (US) patients. We evaluated the diagnostic yield of ES in a cohort of predominantly US and URM pediatric and prenatal patients suspected to have a genetic disorder. Eligible pediatric patients had multiple congenital anomalies and/or neurocognitive disabilities and prenatal patients had one or more structural anomalies, disorders of fetal growth, or fetal effusions. URM and US patients were prioritized for enrollment and underwent ES at a single academic center. We identified definitive positive or probable positive results in 201/845 (23.8%) patients, with a significantly higher diagnostic rate in pediatric (26.7%) compared to prenatal patients (19.0%) (P = 0.01). For both pediatric and prenatal patients, the diagnostic yield and frequency of inconclusive findings did not differ significantly between URM and non-URM patients or between patients with US status and those without US status. Our results demonstrate a similar diagnostic yield of ES between prenatal and pediatric URM/US patients and non-URM/US patients for positive and inconclusive results. These data support the use of ES to identify clinically relevant variants in patients from diverse populations.