Apo E genotyping from blood stored on filter paper

BACKGROUND & OBJECTIVES: Dried blood spotted on to filter paper has been found suitable for a large number of studies. In tropical countries with varying temperature conditions the use of dried blood needs to be validated. We carried out this study to assess the use of blood spotted filter paper as a transport system to study genotyping of Apo E gene. METHODS: Fifty five patients visiting Cardiothoracic Neuroscience Centre (CNC) OPD at the All India Institute of Medical Sciences (AIIMS), New Delhi, and referred for lipid investigations to Cardiac Biochemistry Laboratory were selected at random. Blood was spotted on to Whatman 3 MM filter paper, dried and stored at room temperature. Genomic DNA was extracted and genotyping was carried out at the end of 0, 3 and 12 months. The study was further validated using samples collected on to filter paper from four centres and stored for eight years at room temperature. The temperature and humidity conditions of the centre varied widely. RESULTS: Fifty five samples collected on to filter paper showed exact match of the genotyping when compared to fresh blood. In dried blood samples collected and stored for 1 yr at room temperature DNA extraction and apo E genotyping was done successfully. INTERPRETATION & CONCLUSIONS: The present results showed the feasibility of using dried blood samples on filter paper for apo E genotyping in tropical temperature. The findings need to be validated on a large sample before being recommended for use.