Continuous reference intervals for leukocyte telomere length in children: The method matters

Objectives: Children with very short telomeres commonly develop bone marrow failure and other severe diseases. Identifying the individuals with short telomeres can improve outcome of bone marrow transplantation, with accurate diagnosis requiring the use of age-matched reference intervals (RIs). This study aimed to establish RIs for telomere length (TL) in children using three commonly used methods for TL measurement. Methods: Healthy children aged 30 days to 18 years were recruited for assessment using age as a continuous variable. Venous blood samples were collected and leukocyte TL was measured using terminal restriction fragment (TRF) analysis, quantitative PCR (QPCR) and flow cytometry with fluorescence in situ hybridization (Flow-FISH). Fractional polynomial model and quantile regression were performed to generate continuous RIs. Factors that might contribute to variation in TL, such as gender, were also examined. Results: A total of 212 samples were analyzed. Continuous RIs are presented as functions of age. TRF analysis and QPCR showed significant negative correlation between TL and age (r=−0.28 and r=−0.38, p<0.001). In contrast, Flow-FISH showed no change in TL with age (r=−0.08, p=0.23). Gender did not have significant influence on TL in children. Conclusions: This study provides three options to assess TL in children by establishing method-specific continuous RIs. Choosing which method to use will depend on several factors such as amount and type of sample available and required sensitivity to age-related change.