From Blood Spots to DNA: Evaluating Isolation Methods for FTA Cards
In the field of molecular biology, the efficient and effective isolation of DNA is crucial for various downstream applications, including genetic analysis, forensic research and disease diagnostics. One of our group’s previous studies entitled “Uji Banding Metode Isolasi DNA Sampel FTA Card menggunakan Kit Wizard” by Dyah Aryani Perwitasari et al. provides a comprehensive comparison of three DNA isolation methods using FTA cards: the Wizard® Genomic DNA Purification Kit, the PureLink® Genomic DNA Kit and the Chelex-100 method. In this article, we will review the key findings of this study, supplemented by recent literature, to provide a holistic view of the challenges and advances in DNA isolation from FTA cards.
The Study: A Comparative Analysis
Methodology
The study involved 16 human blood samples collected using a lancet and placed on FTA cards. These samples were subjected to three different DNA isolation methods:
• Wizard® Genomic DNA Purification Kit (Promega)
• PureLink® Genomic DNA Kit
• Chelex-100 Method
Both qualitative (electrophoresis) and quantitative (spectrophotometry) analyses were conducted to assess DNA purity and concentration.
Key Findings
• PureLink® Genomic DNA Kit with SDS 10%: This method showed thin and smeared DNA bands on agarose gels with purity values ranging between 1.117 to 1.162 and DNA concentrations from 190 to 210 ng/µL. The presence of impurities was indicated by the purity values being less than the ideal 1.8.
• Chelex-100 Method: This method displayed clear DNA bands on agarose gels with purity values between 1.035 to 1.076 and DNA concentrations from 650 to 950 ng/µL. Despite the high DNA concentration, impurities were still present.
• Wizard® Genomic DNA Purification Kit: No visible DNA bands were observed, suggesting the method was not successful under the conditions tested, possibly due to issues with the lysis temperature.
Common Contaminants in DNA Isolation from FTA Cards
The study identified several common contaminants that affect the quality of DNA isolated from FTA cards:
• Proteins: Indicated by low A260/A280 ratios, suggesting protein impurities.
• Phenols: Significant contaminants affecting DNA purity.
• Carbohydrates and Polyethylene Glycol (PEG): Particularly noted in some DNA isolation methods, affecting A260/A230 ratios.
• Chaotropic Agents: Guanidine isothiocyanate used in FTA cards for cell lysis can remain as contaminants.
• Environmental Contaminants: Exposure during the drying process can introduce impurities.
Recent Advances and Literature Insights
Stability and Storage
Recent studies have highlighted the stability of DNA stored on FTA cards. DNA from blood samples stored on FTA cards has been shown to remain stable and suitable for PCR amplification even after several months of storage at room temperature. This makes FTA cards an excellent choice for sample collection and storage, especially in remote areas without refrigeration.
Optimization of DNA Isolation Protocols
Advances in DNA isolation techniques have focused on optimising protocols to improve DNA yield and purity. Automated DNA extraction systems, for example, provide consistent and high-quality DNA, making them ideal for applications such as short tandem repeat (STR) profiling. These systems often incorporate bead-based purification steps that enhance the removal of contaminants, resulting in higher purity DNA.
Applications in Forensic and Diagnostic Fields
FTA cards are widely used in forensic and diagnostic applications. They are used to collect and store biological samples, enabling the extraction of high quality DNA for genetic analysis and disease diagnostics. The ability to transport and store samples at room temperature without degradation makes FTA cards a valuable tool in these fields.
Conclusion
The comparative study by Perwitasari et al. highlights the importance of selecting and optimising DNA isolation methods based on the specific requirements of downstream applications. While the Chelex-100 method provided the highest DNA concentration, all methods tested showed some level of contamination.
Recent advances in DNA isolation techniques and the stability of DNA on FTA cards further enhance their utility in molecular biology, forensics and diagnostics. Continued research and optimisation is essential to overcome the challenges of contamination and to achieve higher purity levels suitable for various molecular analyses.
Further reading:
Perwitasari, D. A., Faridah, I. N., Ratnasari, Y. A., Agustina, K., Utami, I. N., & Maliza, R. (2020). Uji Banding Metode Isolasi DNA Sampel FTA Card menggunakan Kit Wizard. Jurnal Ilmu Kefarmasian Indonesia, 18(2), 241–245.
