DGGE method for the mutational analysis of the coding and proximal promoter regions of the Alzheimer's disease presenilin-1 gene: Two novel mutations

Many different mutations that cause Alzheimer's disease (AD) have been foun d in the presenilin-1 gene (PSEN1) and are associated with the most aggress ive forms of the disease. With the aim of screening for PSEN1 genetic varia tions, we developed a method based on denaturing gradient gel electrophores is (DGGE) that allows the mutational analysis of all the coding exons and t he proximal promoter of PSEN1 using only four DGGE gels. The analysis by th is methodology of a sample of 58 early-onset AD (EOAD) patients nonselected for family history resulted in finding four genetic variants within the PS EN1 coding region, two of which are novel mutations (M233L and A409T), wher eas the other two have been reported previously (L282R and E318G). We also found a novel mutation within the PSEN1 proximal promoter (-280 C-->G) that , interestingly, provokes significant changes in the transcriptional activi ty of the gene in cell lines of neuronal and astrocytic, but not hepatic or igin. These data strongly suggest that the region around -280 of PSEN1 prom oter contains a regulatory element that controls its transcription specific ally in neural cells. Hum Mutat 14:433-439, (C) 1999 Wiley-Liss, Inc.