Determination of telomere length by flow-fluorescence in situ hybridization in Down's syndrome patients.

A new method for measuring telomere length in a population of Down's syndrome patients aged 18-60 years old is presented. The method is based on flow cytometry and quantitative fluorescence in situ hybridization (flow-FISH) on whole cells. At least three methods for measuring the length of telomere repeats have been described: (i) Southern blot analysis, and quantitative FISH using either (ii) digital fluorescence microscopy (Q-FISH) or (iii) flow cytometry (flow-FISH). Both Southern blot analysis and Q-FISH have specific limitations and are time-consuming, whereas flow-FISH needed relatively few cells (1.5-2.5 x 106) and could be completed in 24-48 h. The method can be used to rapidly determine telomere length in subsets of nucleated blood cells from patients with age-related diseases such as Down's syndrome, Alzheimer's disease and Werner syndrome.