Longitudinal monitoring of gene expression in ultra‐low‐volume blood samples self‐collected at home

Blood transcriptional profiles could serve as biomarkers of clinical changes in subjects at‐risk for or diagnosed with diabetes. However, transcriptional variation over time is poorly understood due to the impracticality of frequent longitudinal phlebotomy in large patient cohorts. We have developed a novel transcriptome assessment method that could be applied to fingerstick blood samples self‐collected by study volunteers. Fifteen μL of blood from a fingerstick yielded sufficient RNA to analyse > 176 transcripts by high‐throughput quantitative polymerase chain reaction (PCR). We enrolled 13 subjects with type 1 diabetes and 14 controls to perform weekly collections at home for a period of 6 months. Subjects returned an average of 24 of 26 total weekly samples, and transcript data were obtained successfully for > 99% of samples returned. A high degree of correlation between fingerstick data and data from a standard 3 mL venipuncture sample was observed. Increases in interferon‐stimulated gene expression were associated with self‐reported respiratory infections, indicating that real‐world transcriptional changes can be detected using this assay. In summary, we show that longitudinal monitoring of gene expression is feasible using ultra‐low‐volume blood samples self‐collected by study participants at home, and can be used to monitor changes in gene expression frequently over extended periods.