DNA will be extracted from buccal epithelial cells. Telomere length will be measured by the method adapted from that originally published by Cawthon. For each sample, the telomere length will be represented by the relative ratio of the telomere repeat copy number (T) to the single copy gene 36BA copy number (S). The T/S ratio will be determined by quantitative polymerase chain reaction (qPcR) using a 7900HT Thermocycler (Applied Biosystems).