Sarah Knapton, Telegraph (London), December 11, 2013
Identical twins need never again be tried for the same crime after scientists found first proof that they are not genetically the same.
Forensic scientists have discovered there is a subtle genetic difference in the DNA of twins which were previously thought to be entirely identical.
The breakthrough means there is now a definitive test to find out which twin has been at the crime scene or has fathered a child.
In August detectives arrested Aftab and Mohammed Asghar, both 22, after recovering DNA from the jumper of 17–year–old girl who was allegedly attacked by at least three men in a Reading park at night.
However the prosecution eventually offered no evidence against Aftab when analysis of his mobile phone showed that he was in another location at the time of the alleged assault.
Until now geneticists have not been able to prove that identical twins–also known as monozygotic twins–are not genetically identical.
But in a breakthrough a forensic laboratory found the subtle difference at a genetic level which could prove vital in solving crimes and paternity cases involving identical twins.
Scientists used high tech sequencing of DNA from sperm samples from one set of twins and from a blood sample from a child of one of them.
Bioinformatics analysis in a forensics lab revealed five mutations, called “Single Nucleotide Polymorphisms” (SNPs) present in the twin father and the child, but not in the twin uncle.
The results suggest that rare mutations will occur early after or before the human blastocyst (a pre-embryonic form) has split in two – the origin of twins.
Dr Bruno Poddevin, Senior Vice-President of the Genomic Services division and head of the Forensics laboratory at Eurofins, said: “Eurofins scientists are the first to proof that monozygotic twins are genetically not absolutely identical.
“As the only provider worldwide Eurofins can now offer DNA forensic and paternity testing to discriminate identical twins to authorities, courts and individuals.
“Our leading genomic and forensic services team has provided the basis for reaching this milestone.
“As the first provider of next generation sequencing services in Europe, Eurofins also has proprietary, long expertise in the professional handling and analysis of the enormous amount of data involved in such a project.
“The dataset in this project equalled a total of 241 human genomes, resulting from up to 94 fold genomic coverage of the involved three individuals.”
The study was published in the journal Forensic Science International.