Improved method for detecting mutant DNAs

A group of researchers in Korea describe a simple and inexpensive enrichment technique that they have termed mutant enrichment with 3′-modified oligonucleotides (MEMO). This oligonucleotide blocks extension of the normal gene but enables extension of the mutated gene, allowing for increased detection sensitivity.

"The potential applications of MEMO include all situations in which minority alleles of clinical significance are present and sensitive detection is required," commented lead investigators Seung-Tae Lee MD, PhD, and Chang-Seok Ki, MD, PhD, Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. "In addition to the application of MEMO to detect cancer mutations, it can be used in other situations, such as variant strain identification in infectious diseases (for example, the YMDD mutation in hepatitis B virus infection and antiviral drug-resistant variants in human immunodeficiency virus infection), minor mutant allele detection in patients with low-level somatic mosaicism or mitochondrial heteroplasmy, and characterization of fetal mutations from maternal plasma samples."

Using genomic DNA extracted from cancer-derived cell lines containing EGFR, BRAF, JAK2, TP53, or KRAS mutations and from a bone marrow sample containing an NPM1 mutation, the authors were able to demonstrate significant sensitivity to these mutations.

Compared to preexisting methods, MEMO was shown to provide an improved diagnostic performance so that the method can be easily applicable in various medical fields, where molecular assays are important for disease diagnosis or treatment monitoring, and thus may help to improve patient outcomes.