Blood Biomarkers to Identify Renal Angiomyolipomas in People With Tuberous Sclerosis Complex

Abstract

Background and ObjectivesRenal angiomyolipomas (AMLs) affect 80% of people with tuberous sclerosis complex (TSC) during their lifetime. We aimed to determine the diagnostic accuracy of blood biomarkers in identifying the presence and size of renal AMLs in people with TSC.MethodsWe collected clinical data and serum samples from individuals followed at 1 TSC clinic (Centre hospitalier de l'Université de Montréal [CHUM] cohort). We also obtained clinical data and plasma samples from participants in the TSC Alliance Natural History Database and Biosample Repository (TSC Alliance cohort). We measured vascular endothelial growth factor D (VEGF-D), kidney injury molecule 1, neutrophil gelatinase-associated lipocalin (NGAL), and cystatin C concentrations in all individuals. We computed receiver operating characteristic curves for each biomarker and determined the optimal thresholds to identify AML vs no AML, and large AML (≥ 3 cm in diameter) vs small/no AML.ResultsThe CHUM and TSC Alliance cohorts included 41 (23 with AML) and 38 (26 with AML) individuals, respectively. In both cohorts, VEGF-D had the greatest area under the curve, with a sensitivity of at least 0.80 (95% CI 0.49-0.94) and a specificity of at least 0.97 (95% CI 0.83-0.99) in identifying large AML. When VEGF-D and cystatin C were combined, sensitivity increased to 0.96 (95% CI 0.79-0.99) and 1.00 (95% CI 0.72-1.00) for AML presence and size, respectively, in the CHUM cohort. Similar results were observed in a second, independent cohort (the TSC Alliance cohort) when combining VEGF-D and NGAL.DiscussionVEGF-D with either cystatin C or NGAL can accurately screen for large renal AMLs in people with TSC. Smaller renal AMLs can also be screened using these biomarkers, albeit with lower accuracy. Further research is necessary to determine how to implement these biomarkers in clinical practice.