In the second set of human brain tissue samples, quantitative biochemical and molecular biological analyses were performed with the aim (1) to validate a possible role of isoQC in pGlu-Abeta and pGlu-CCL2 formation in human brain and (2) to analyze biochemical alterations such as expression of isoQC as well as pGlu-Abeta and pGlu-CCL2 formation with regard to a possible association with the clinical severity of AD as assessed by MMSE. The gene discussed is APP; the disease is Alzheimer disease.