DNA Methylation Episignature as a Novel Diagnostic Tool for Diamond-Blackfan Anemia Syndrome.

Diamond-Blackfan Anemia Syndrome (DBAS) is a rare inherited bone marrow failure syndrome (IBMFS) characterized by impaired erythropoiesis and significant genetic heterogeneity. Diagnosis can be challenging due to clinical variability and the lack of sensitive and specific biomarkers. We investigated the evidence for a DNA methylation (DNAm) episignature in a cohort of 80 DBAS patients with causative variants in various ribosomal protein genes: DBA1 (RPS19, n = 30), DBA4 (RPS17, n = 6), DBA5 (RPL35A, n = 8), DBA6 (RPL5, n = 15), DBA7 (RPL11, n = 13), DBA10 (RPS26, n = 8). We identified a distinct and highly accurate episignature biomarker for DBAS, clearly differentiating it from both Fanconi anemia and a broad spectrum of other episignature-positive disorders. Furthermore, we developed a specific DNAm classifier for the clinically similar DBA6 and DBA7 subtypes. Applying the DBAS episignature analysis to six molecularly uncharacterized cases, three exhibited the DBAS pattern. Subsequent genome sequencing identified causative genetic variants in two (RPL5: c.325-380A>G:p.?; RPL26: c.-6 + 3_-6 + 25del:p.?), validating the test robustness. Methylation profiles from two revertant cases (RPS19:P47L and RPS17 full gene deletion) exhibited the DBAS episignature, suggesting it to be a stable epigenetic mark associated with the underlying genetic mutation, likely established early in development. In conclusion, we propose DNAm profiling as a robust diagnostic tool for DBAS, providing a biomarker applicable to all patients with clinical suspicion of the disease and critically aiding in the resolution of variants of uncertain significance and molecularly uncharacterized cases.