Detection Of H-FABP As A New Potential Diagnostic Marker And Studies On Prion Protein Gene In Sporadic Creutzfeldt-Jakob Disease.

Creutzfeldt-Jakob Disease(CJD) is one of the most commontransmissible spongiform encephalopathies(TSE) and is infectious,inherited, or sporadic encephalopathies with a poor prognosis andlong latency. It is a rapidly progressive and ultimately fataldisorder of the central nervous system. Diagnosis of CJD can onlybe definited at postmortem examination or brain biopsy showing thepathological isoform of the prion protein (PrPSc). Brain biopsy,however, is not accepted by patients and may result in iatrogenictransimission. It is necessary to find a new way in the diagnosisof CJD.Up to now, the diagnosis has been made according to clinicaland EEG criteria.The aim of our study is to evaluate whether Heart-type fattyacid-binding protein(H-FABP) is a biomarker for the diagnosis of CJD.Therefore we measured H-FABP concentration in cerebrospinal fluid(CSF) and serum of CJD patients, other dementia patients and a healthycontrol group using an enzyme linked immunoassay (ELISA). In thegroup of 17 patients with CJD, H-FABP concentrations in CSF weresignificantly higher than in other dementias group and the controlgroup,(median 1726.71 pg/ml, range 682.47～5008.62 pg/ml;P<0.01).The other dementias group comprised 5 patients who were diagnosedas having other dementing diseases (H-FABP concentration: median705.32 pg/ml, range 449.93-1219.18 pg/ml). The healthy control groupcomprised 12 healthy persons (H-FABP concentration: median 540.54pg/ml, range 179.85-897.49 pg/ml). Calculating the cut-off point forthe CJD group and the others, best results were obtained at a levelof 960 pg/ml. At this cut-off point, sensitivity for diagnosis ofCJD is 88.2% and specificity is 94.1%. The positive predictive valueis 93.8% and the negative predictive value is 88.9%, respectively.H-FABP concentrations in serum were measured in 13 CJD patients andthere was a significant difference between the CJD group ( median1932.33 pg/ml, range 822.98-6073.53 pg/ml;P<0.01) and the two others.The other dementias group comprised 8 patients (H-FABP concentration:median 1041.92 pg/ml, range 360.67-1583.87 pg/ml). The healthycontrol group comprised 13 healthy persons (H-FABP concentration:median 668.44 pg/ml, range 180.43-1124.22 pg/ml). Calculating thecut-off point for the groups of CJD and the other two groups in serum,best results were obtained at a level of 1200 pg/ml. At this cut-offpoint, sensitivity for diagnosis of CJD is 76.9% and specificity is90.5%. The positive predictive value is 83.3% and the negativepredictive value is 86.4%, respectively. In our study, Levels ofH-FABP in CJD patients were significantly higher than that in theother dementia group and the control group in CSF and serum. Itsuggested that H-FABP might be a new potential biomarker fordiagnosis of sporadic CJD in CSF and serum. Using a suitable cut-offwe can differentiate CJD and the other dementias. Our results suggestthat H-FABP might be a useful biomarker for the differentialdiagnosis of dementias, especially when serum and CSF are determinedin parallel. Because H-FABP might be a potential plasma biomarkerfor CJD, screening the blood donors during examining the H-FABPconcentration in serum, it is possible to decrease the risk of theiatrogenic infection through blood transfusion.We study the change of H-FABP in the brain tissues of 4 CJDpatients by immunohistochemistry. There was no H-FABP depletion innormal brain tissues, while obvious depletion was observed in CJDpatients. Among 4 CJD group, 3 case showed obvious depletion and 1case showed vague depletion for H-FABP. H-FABP is a small proteinwhich may escape into the CSF and blood circulation from brain whenbrain injury occurred. It is indicated that H-FABP could reflectbrain injury in CJD patients. We consider that H-FABP can be usedto diagnosis early CJD.Genomic DNA from 10 CJD subjects was used to amplify the codingregion of PRNP in the polymerase chain reaction with the primers.Mutations were detected by direct sequencing of PRNP open readingframe. The cordon 219 genotype was examined by digestion with therestriction end nuclease Bigwig in 10 CJD subjects. One probable CJDcase showed a mutation at codon 211 involving substitution ofglutamic for aspartate (E211D). E211D was a rare novel prion proteingene mutation and it might associate with CJD. Our researching groupreported this mutation last year. We consider that the mutationprobably is a special mutation in Chinese. We did not find thepolymorphism at codon 219 and all the subjects are glutamichomozygosis. In future, we should investigate the polymorphism atcodon 219 in larger CJD sample and healthy Chinese.