Club contact: Andrew Grant
andygrantrwg@yahoo.co.uk
March 2024 – update
An excellent meeting with a talk by Dr. Rhian Morgan
“Genetics”
Dr. Rhian Morgan is a Senior Education and Engagement Officer at Wales Gene Park, which is affiliated with Cardiff University. Her background lies in biomedical research, and she has worked in academic, industrial, and clinical settings.
Genetics is the study of genes, genetic variation, and heredity in organisms. It is an important branch in biology because heredity is vital to organisms’ evolution.
The molecular basis for genes is deoxyribonucleic acid (DNA). DNA is composed of deoxyribose (sugar molecule), a phosphate group, and a base (amine group). There are four types of bases: adenine (A), cytosine (C), guanine (G), and thymine (T). The phosphates make hydrogen bonds with the sugars to make long phosphate-sugar backbones. Bases specifically pair together (T&A, C&G) between two backbones and make a structure like rungs on a ladder. The bases, phosphates, and sugars together make a nucleotide that connects to make long chains of DNA Genetic information exists in the sequence of these nucleotides, and genes exist as stretches of sequence along the DNA chain. These chains coil into a double a-helix structure and wrap around proteins called histones which provide the structural support. DNA wrapped around these histones are called chromosomes. Viruses sometimes use the similar molecule RNA instead of DNA as their genetic material.
The human Genome contains about 3.2 billion pairs and was fully sequenced in 2010. DNA can be extracted from all cells using salt, alcohol and a detergent and appears as a white fluffy clump. A chromosome is a package of DNA with part or all of the genetic material of an organism with humans having normally 46 in 23 pairs with females having one pair of XX and males having an XY. Several genetic diseases arise from incorrect chromosomes e.g. Downs Syndrome when victims have an extra chromosome.
The DNA recipe tells cells what to make and with health clearly linked to genes a lot of work is currently active to create personalised gene medicine. Genetic variation is nearly identical for each person with 99.9% the same but 0.1% different, exception is identical twins/triplets.
The rest of the talk related to the forensic applications which make use of the specific nature of DNA. In 1984 the first DNA fingerprinting was used with the STR (Short Tandom Reports) technique and the first national database was established in the mid- 1990s.
Several cases using DNA essential in solving crimes were given:
Murders of Linda Mann (1983) and Dawn Ashworth (1986) – Semen samples showed the same Blood type for the murderer. The Leicestershire police arranged for several thousand locals to give samples of Blood and Saliva and found no match. However, a conversation overheard in a pub that Ian Kelly had given his samples under a false name of Colin Pitchfork was reported to the police and they retook samples from Pitchfork which turned out to match both the murders and resulted in him receiving a 30 year life sentence.
Mr Little died in March 2003 as he drove his vehicle on the M3 in Surrey. A brick crashed through his window after being thrown from a footbridge above the motorway, causing him to suffer a fatal heart attack. The DNA profile was checked against the national database, but because the killer, Craig Harman, did not have a criminal record no match came up. It was then Surrey Police with the Forensic Science Service, decided to use the intelligence-led DNA screening and familial searching. The technique, which is based on the fact that individuals who are related are more likely to have similar DNA, had been launched a few months before. Using the new technique, 25 people with similar DNA were located and Harman’s relative was top of the list. The family were then tested and Craig Harman was then caught after giving a DNA sample which matched exactly.
Shirley Duguay was a Canadian woman from Prince Edward Island who went missing in 1994 and was later found dead in a shallow grave. Among the most compelling pieces of evidence in the case was a leather jacket covered in Duguay’s blood and over two dozen white feline hairs, marking the world’s first use of non-human DNA in a criminal trial. The investigators remembered that in a previous discussion Shirley’s common law husband had made reference to Snowball their cat. So samples were taken from this and 20 other cats and found the DNA match to be specific for this one and so the husband was convicted of the murder. DNA libraries now exist for many cats and dogs in the UK.
Melanie Road was murdered in 1984 and 32 years later her killer was identified. In 2014 the killer’s daughter was arrested for a domestic crime and her DNA put onto the database and when tested provided a familial match to the samples from Melanie’s murder and her father was then tested and arrested.
Other examples included Joseph Mengele the South American Nazi being identified despite his name changes, Nicholas II his family and the false claim from someone purporting to be Anastasia and O..J. Simpson proving he did not murder his wife, were all very involved with DNA technology.
Please contact me for any further information at the e-mail address above or on 02920252422.
Although our membership is growing, we still have room for new people and I would be glad to hear from any interested parties. We meet on the second Thursday of each month at the Llanishen Golf Club in Cardiff at 10am for coffee before starting the meeting proper at 10.30am. Lunch is available at the club and the great majority of the members stay for this excellent value meal.
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Andrew Grant (Secretary)