Discipline
Molecular genetics
Molecular genetics studies the structure and function of genes at the level of DNA and RNA. Its laboratory methods are the toolkit of forensic DNA analysis.
Techniques
Core laboratory techniques
PCR and qPCR
The polymerase chain reaction copies a chosen DNA region; real-time PCR measures how much DNA a sample contains.
Sanger sequencing
Reads one DNA fragment base by base; still the reference method for confirming variants.
Next-generation sequencing
Sequences millions of fragments in parallel, from targeted panels to whole genomes.
RNA analysis
Messenger RNA and microRNA markers show which tissue or body fluid a stain came from.
DNA methylation
Chemical marks on DNA change with age, allowing the age of an unknown donor to be estimated.
Bioinformatics
Software aligns reads, calls variants and checks quality in sequencing data.
History
Milestones
1953
The double helix
Watson and Crick describe the structure of DNA, building on Rosalind Franklin’s X-ray data.
1977
Sanger sequencing
Frederick Sanger’s chain-termination method makes DNA sequencing practical.
1985
PCR published
Kary Mullis and colleagues publish the polymerase chain reaction.
2003
Human Genome Project
The reference sequence of the human genome is completed.
2005
Next-generation sequencing
The first commercial massively parallel sequencers reach laboratories.
References
- Sanger F, Nicklen S, Coulson AR (1977). DNA sequencing with chain-terminating inhibitors. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.74.12.5463
- Saiki RK, Scharf S, Faloona F, Mullis KB, et al. (1985). Enzymatic amplification of β-globin genomic sequences and restriction site analysis for diagnosis of sickle cell anemia. Science. doi:10.1126/science.2999980