Abstract
BackgroundLarge epidemiological studies in DNA biobanks have increasingly used less invasive methods for obtaining DNA samples, such as saliva collection. Although lower amounts of DNA are obtained as compared with blood collection, this method has been widely used because of its more simple logistics and increased response rate. The present study aimed to verify whether a storage time of 8 months decreases the quality of DNA from collected samples.MethodsSaliva samples were collected with an OrageneTM DNA Self-Collection Kit from 4,110 subjects aged 14–15 years. The samples were processed in two aliquots with an 8-month interval between them. Quantitative and qualitative evaluations were carried out in 20% of the samples by spectrophotometry and genotyping. Descriptive analyses and paired t-tests were performed.ResultsThe mean volume of saliva collected was 2.2 mL per subject, yielding on average 184.8 μg DNA per kit. Most samples showed a Ratio of OD differences (RAT) between 1.6 and 1.8 in the qualitative evaluation. The evaluation of DNA quality by TaqMan®, High Resolution Melting (HRM), and restriction fragment length polymorphism-PCR (RFLP-PCR) showed a rate of success of up to 98% of the samples. The sample store time did not reduce either the quantity or quality of DNA extracted with the Oragene kit.ConclusionThe study results showed that a storage period of 8 months at room temperature did not reduce the quality of the DNA obtained. In addition, the use of the Oragene kit during fieldwork in large population-based studies allows for DNA of high quantity and high quality.
Highlights
Large epidemiological studies in DNA biobanks have increasingly used less invasive methods for obtaining DNA samples, such as saliva collection
Widely used as a source of genetic material, there are some limitations for determining the amount of DNA obtained from buccal cells, because the concentration can differ between individuals and may contain non-human DNA, degraded or with contaminants
The samples containing OrageneDNA/saliva mixed were taken to a laboratory where their transparency was examined, after which they were stored at room temperature until processing
Summary
Large epidemiological studies in DNA biobanks have increasingly used less invasive methods for obtaining DNA samples, such as saliva collection. Epidemiological studies for the development of DNA biobanks have increasingly used less invasive methods for extracting genetic material, such as collection of buccal epithelial cells from saliva [1,2]. For DNA quantification, the fastest and least expensive method is ultraviolet (UV) spectrophotometry Other methods for this measurement include agarose gel electrophoresis, fluorescent dyes, such as Hoechst and PicoGreensTM, real- time polymerase chain reaction (RT-PCR), and hybridization techniques. These methods have high correlations with quantification measurements [11], they all can lead to biased quantification, especially in samples with low DNA concentration [21]
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