Genotyping of DNA samples under adverse conditions of Low Copy Number—LCN (formolisados tissue samples and embedded in paraffin)

Abstract

This paper aims to describe and evaluate a protocol for extraction of DNA (deoxyribonucleic acid) in formalinized tissues and embedded in paraffin for forensics genetic analysis. In outline the method is the removal of paraffin with an organic solvent in 0.3–0.5 mg of the sample of the tissue under study, followed by removal of formaldehyde, rehydration and soon after the extraction of genomic DNA. The extraction is achieved through the stages of cellular lysis, enzymatic digestion of proteins and DNA precipitation in ethanol medium. With the research we can conclude that even when the DNA is present in small quantities in conditions of extreme difficulties in its extraction, as formalinized tissues and embedded in paraffin, the technique of optimizing the extraction of DNA used both to organic extraction as Chelex, for use in the polymerase chain reaction (PCR), and possible the investigation of different samples of human tissue, biological samples, or was obtained under the conditions tested, a DNA with good quality and concentration. The samples were amplified for the mini-STRs loci using the product marketed in multilocus, using a methodology recommended by the supplier and validated for analysis of forensic DNA. Commercial kit was used MiniFiler from Applied Biosystems. The DNA fragments amplified by PCR showed that the extracted DNA had good amplification.