Paraneoplastic Cerebellar Degeneration

Abstract

ObjectiveInvestigate the value of including cerebellar degeneration-related protein 2-like (CDR2L) as a marker in commercial diagnostic tests for anti-Yo–associated paraneoplastic cerebellar degeneration (PCD).MethodsWe included sera and CSF samples from 24 patients with suspected PCD (6 of whom had PCD with underlying gynecologic or breast cancer), who were positive for Yo antibodies using the commercially available, paraneoplastic neurologic syndromes (PNS) 14 Line Assay from Ravo Diagnostika. The samples were further evaluated using the EUROLINE PNS 12 Ag Line Assay and a cell-based assay (CBA) from Euroimmun. For confirmation of positive lineblot results, we used indirect immunofluorescence of rat cerebellar sections. We also tested all samples in 2 assays developed in-house: a CBA for CDR2L and a Western blot analysis using recombinant cerebellar degeneration-related protein 2 (CDR2) and CDR2L proteins.ResultsIn PNS 14 and PNS 12 Ag Line Assays, anti-CDR2 reactivity was observed for 24 (100%) and 20 (83%) of the 24 samples, respectively. Thirteen of 24 subjects (54%) were also positive using the Euroimmun CBA. Rat cerebellar immunofluorescence was the best confirmatory test. In our in-house CBA for CDR2L and Western blot for CDR2 and CDR2L, only the 6 patients with confirmed PCD reacted with CDR2L.ConclusionsCommercially available tests for Yo antibody detection have low specificity for PCD because these assays use CDR2 as antigen. By adding a test for CDR2L, which is the major Yo antigen, the accuracy of PCD diagnosis greatly improved.Classification of EvidenceThis study provides Class III evidence that a CBA for CDR2L accurately identifies patients with PCD.

A cerebellar degeneration‐related protein 2‐like cell‐based assay for anti‐Yo detection in patients with paraneoplastic cerebellar degeneration

“…In our previous study, we reported that inclusion of CDR2L as an additional Yo antibody target increases test specificity and therefore serves as an important diagnostic biomarker for Yo‐PCD [8]. In this follow‐up study, we further validated our CBA in comparison to western blot and line immunoassay techniques in a larger patient cohort and additional control groups.…”

“…We found that the CDR2L CBA identified all 48 patients with Yo‐PCD, and was negative for the 15 non‐PCD patients, 22 patients with ovarian cancer without neurological syndromes and 50 healthy blood donors. In our previous study, 24 patient sera that tested positive for anti‐Yo by line immunoassay were evaluated by CDR2L CBA and western blot analysis with recombinant CDR2 and CDR2L proteins [8]. Only the six true‐positive anti‐Yo PCD sera tested positive in the CDR2L CBA, rendering the 18 remaining sera false positive.…”

“…All patients were diagnosed with Yo‐associated PCD prior to inclusion, using line immunoassays, confirmed by immunohistochemistry, and supported by clinical findings. None of the Yo‐PCD patients were included in our previous study [8]. Controls consisted of 15 patients from Lyon with PCD without Yo antibodies, as well as 22 patients with ovarian cancer without neurological syndrome, 50 healthy blood donors, 10 patients with multiple sclerosis, 15 patients with Parkinson's disease and five patients with non‐paraneoplastic ataxia (mitochondrial disease with polymerase gamma [POLG] mutation), from Bergen.…”

“…Anti‐Yo targets two antigens located in the nucleus and cytoplasm of Purkinje neurons, cerebellar degeneration‐related protein 2 (CDR2) and CDR2‐like (CDR2L), respectively. Experimental findings strongly suggest that CDR2L is the major Yo antibody target in PCD patients [6–8].…”

CRMP5 Antibodies—Diagnostic Challenges

“…Most laboratories use commercial line assays and /or immunohistochemistry to detect CRMP5 antibodies. While line assays are easy to perform, they can give false positive results ( 9 , 10 , 16 ). Therefore, another confirmatory test is needed for the line assays.…”