PCR amplification is performed in a ABI PRISM 7900 (Applied Biosystem). In each plate, a standard curve is produced ranging from 4 to 80 ng of human reference DNA (Applied Biosystem). The thermal cycling profile for the telomere amplification is 95°C for 10 min, followed by 30 cycles of 95°C for 5 s, 56°C for 10 s and 72°C for 60 s or 30 cycles of 95°C for 5 s, 58°C for 10 s and 72°C for 40 s. Following amplification, a dissociation curve is performed in order to confirm the specificity of the reaction. All samples are assayed in triplicate to test the reproducibility of assay and in each assay a negative control is evaluated.