Forensic kit to help ID rapists


Ray Maota

The Y chromosome (on the right) is
present only in male DNA.
(Image: Science Photo Library)

A forensic scientist examines clothing
for DNA.
(Image: Center for Genetics and Society)

Luthando Tyhalibongo
Media Relations Officer, UWC
+27 21 959 2625

A kit that can help identify male rapists has been developed by researchers under the leadership of Prof Sean Davidson at the forensic DNA laboratory at the University of the Western Cape (UWC).

The Y chromosome research at the UWC’s Department of Biotechnology, which led to the kit, could also help exclude innocent men mistaken as perpetrators.

DNA is the abbreviation for deoxyribonucleic acid, a chemical found in almost every cell in the human body which carries genetic information passed on from one generation to the next.

Dr Eugenia D’Amato, a research scientist at the UWC’s DNA forensic lab, said: “The findings and results had been welcomed by the international forensics community and had been hailed by UWC as a feather in its cap and a giant step forward for justice and rape victims in South Africa.”

The research took three years to complete and started with the isolation of genetic information in the Y chromosome, present only in male DNA. The research results have enabled the narrowing down of the aggressor to a range of father, son and brother.

Davidson said: “Forensic pathologists could pick up male DNA more easily in a rape case, and this made it more useful in identifying the rapist, with investigators able to narrow down the range of possible aggressors.

“The technology is also good at excluding innocent men.”

Similar kits previously available in the US and Europe could not be used by the South African police (SAP), so this prompted local research. The overseas kits didn’t incorporate the genetic diversity of African populations and were therefore unsuitable for testing on South African individuals.

The SAP uses kits that identify both male and female DNA, and this new kit will supplement them.

Davidson said: “The UWC research team looked at local regions with high gene variability between individuals, and the kit they developed was thoroughly tested against South Africa’s different population groups.”

Although the kit is not yet commercially available, the UWC will publish a database of African populations’ genetic profiles shortly.

A DNA profile is a unique set of numbers obtained from a person’s DNA and acts as a kind of personal identification number. Profiling can also be used to show how people are related and to identify human remains.

Y-DNA research

“Identification of spermatozoa is the biological evidence most often sought in specimens from rape victims,” according to Forensic Science International.

“Absence of spermatozoa usually terminates biological investigations, and the victim’s testimony can be contested.”

This basically means that when a rape victim is examined by a doctor, sperm from the perpetrator is the first thing that they look for and its absence on the victim could put the case in jeopardy.

Forensic Science International is a journal that publishes different scientific disciplines connected to the forensic sciences such as biochemistry and toxicology.

Association with Tutu

The UWC was established in 1959, first taking the name of the University College of the Western Cape.

The university held a seminar on Y-DNA on 10 March 2011 to explain how its findings can help solve criminal cases.

The seminar was attended by international experts from the University of Porto, Oxford University, University of Buenos Aires and the University of Berlin. All experts presented results of their research related to African populations.

Archbishop Emeritus Desmond Tutu, who has been chancellor of the university for nearly two decades, said at his send-off on 9 March 2011: “I have been chancellor of this splendid university for longer than you can care to remember and it has been a great privilege to be associated with this outstanding institution.”