The founder R304* AIP mutation is prevalent in Irish acromegaly and gigantism patients as well as in the general population of Ireland

Alzheimeru0027s disease (AD) and frontotemporal dementia (FTD) represent an importantdifferential diagnostic problem in clinical practice. The identification for new biomarkers thatwould help establishing the diagnosis and primary cause of the dementia is therefore of greatrelevance. The aim of this study was to investigate the diagnostic accuracy of three potentialCSF biomarkers, total tau protein (t-tau), tau protein phosphorylated at threonine 181 (p-tau181)and tau protein phosphorylated at serine 199 (p-tau199) in the differential diagnosis of AD andFTD patients in relatively young age groups. The concentrations of these three CSF biomarkerswere measured in 25 FTD patients, 27 AD patients and 25 control subjects. The CSFconcentrations of all three markers were significantly higher in AD than in FTD patients (p u003c0.001) or control subjects (p u003c 0.001). No difference was observed in FTD patient groupcompared to controls, except for p-tau181 (p = 0.028). When sensitivity was set at 85% orhigher, specificity in differentiation between FTD and AD patients reached 40,0% for t-tau,37,5% for p-tau181 and 56,0% for p-tau199. Improvement of the diagnostic accuracy uponlogistic regression analysis with t-tau and p-tau199 as independent variables showed that 22 outof 25 FTD patients could be correctly classified. In conclusion, none of the markers per sefulfilled the criteria for the „ideal“ marker (sensitivity and specificity higher than 85%).However, combination of t-tau and p-tau199 detected correctly 88% of FTD patients, thuslargely satisfying practical requirements.