Increase of homozygosity in centenarians revealed by a new inter-Alu PCR technique

In the present study a novel inter-Alu PCR technique that allows one to det ect inter-individual differences in the genomic regions flanked by Alu repe titive sequences was developed. Two primers complementary to sequences pres ent in different Alu repeats and marked with two different fluorochromes we re used in the same PCR reaction, and the PCR products were separated and a nalyzed by capillary electrophoresis using an automatic sequencer. The meth od is highly reliable, and three patterns of peaks (QM376-400, QM780-790 an d QM480) appeared to be representative for germ-line polymorphisms, as sugg ested by the results obtained in nine couples of monozygotic twins and four three-generation families. The frequency of these polymorphic peaks was st udied in two different age groups (100 young subjects and 69 centenarians). In two out of the three regions (QM376-400 and QM480) a significant increa se in homozygote genotypes frequency was observed in centenarians, These co unterintuitive results suggest that increased homozygosity contributes to h uman longevity. This novel inter-Alu PCR approach could represent a valuabl e tool to identify longevity-associated DNA sequences interspersed througho ut human genome, without making any a priori assumption about their nature and function. (C) 2001 Published by Elsevier Science Inc.