A bit of Forensics
I am new in writing blogs or stories online, I do not have very active social media profiles.
I work in the lab and study MSc Forensic Science, do not ask me why I have chosen to study this…although there is a long story behind it. Long story short I do not have student loan, so I work hard and a lot in the lab to pay off my studies.
So why I have decided to write this post? No, I am not here to complain how hard my life is to study and work at the same time. I am here to share something interesting. I have done a coursework for one of my subjects and I loved the topic and I have found some information that was very interesting for me, after I have finished that coursework I have decided that I will post a small part of it online, because I am sure there will be some people who will enjoy reading it, maybe they will find it useful or maybe I will inspire someone to study Forensic Science. If you are interested please continue to read. Enjoy!
The question that we got to answer is about alternative genetic markers that could be used to help identifying a person.
There are additional genetic markers that have been found as an alternative for the STR analysis. Further literature search has been carried out for an alternative genetic markers.It gave some other potential methods for other genetic markers that could have been used for the identification.
One of the potential forensic identification methods could be INDEL or insertion-deletion polymorphism. As this article mentions that there are two most frequent and mostly used methods: short tandem repeat polymorphisms (STRP) and single nucleotide polymorphism (SNP). Although STR is the most universal technique for the forensic human identification, yet they have limitations such as elaborated procedures which are costly. These inhibitor interferences could be solved by recently developed approach INDEL. As reported by V. Murthy, this technique can assist in the identification of the remains where only limited volume of sample is available. Additionally, author has mention, that INDELs are most abundant and they are more straightforward to be genotyped compared to previously mentioned two methods, STR and SNP (V. Murthy et al, 2015). It has been mentioned in the same article that INDEL can be analysed with simple PCR followed by electrophoresis. Although this technique is a good alternative for limited samples, it has been discussed by V. Murthy et al, that not all INDELs are very informative in different populations, but they good to use for highly decomposed and skeletonised human remains (V. Murthy et al, 2015).
Mitochondrial DNA or mtDNA is exclusively inherited from the mother throughout the generations. As reported by A. Amorim et al, due to lack of recombination and high copy numbers the mtDNA can be very advantageous in forensic cases. As a result of lack of recombination maternal relatives could provide a sample that can be used as a reference for the identification. This is a valuable technique, because the maternal samples could be from different generations. According to A. Amorim et al, scientists have developed a method that is called next generation sequencing or NGS. mtDNA is an excellent tool that can be used on heavily decomposed skeletal remains. One of the most famous cases which was solved using mtDNA is Tsar Nicholas II. This genome information provides information about the ancestors, this could be used for the determining who is the suspect, their background. To sum up, this is potential alternative method which can be used to determine the identification of the remains (A. Amorim et al, 2019).
Y-STR or also known as Y chromosome haplotyping. Even though this method is good for the crime such as sexual assault cases, but it could be one of the potential methods to identify the male individual, but as L. Roewer mentions in his article, Y-STR can be used for the mass disaster investigations. Like mtDNA is maternal specific, Y-STR is male specific. Moreover M. Kayser states that in the past decade the STR loci grew more and they have higher power of discrimination. As it was mention before, the Y chromosome is transmitted without recombination from father to son, this helps to determine the parental lineage (M. Kayser, A. Sajantila, 2001).
To sum up, INDEL,Y-STR and mtDNA methods have their advantages and disadvantages, but as an alternative identification method they could have been applied to this case. For example, the Y-STR would have identified the male remains. Using mitochondrial DNA would require the maternal sample to be used as a reference, but that could have been easily gotten from the family member. INDELs are good for highly degraded samples, in this case it would be applicable, because the remains were highly decomposed. All above methods would be a good alternative to use.
Resources that has been used:
Amorim A, Fernandes T, Taveira N. 2019. Mitochondrial DNA in human identification: a review. PeerJ7:e7314
Kayser M, Sajantila A. (2001). Mutations at Y-STR loci: implications for paternity testing and forensic analysis. Forensic Science International. 118, 116–121.
Murthy V, Jia L F, V. Samueland P, Kademane K. (2015). Forensic Identification by Using Insertion-deletion Polymorphisms. International Journal of Human Genetics. 15 (2), 55–59.
Roewer L. (2009). Y chromosome STR typing in crime casework. Forensic Science, Medicine, and Pathology. 5, 77–84.