News | 7 June 2018

New test traces rare genetic defects in blood relatives

New technique allows couples in consanguineous relationship to take informed decision

Maastricht UMC+ has developed a new test that traces rare genetic defects in couples who are related by blood, such as first and second cousins. The children born of such consanguineous relationships are more likely to have a genetic defect or cognitive impairment because of their parents’ close genetic resemblance. The new test is available as of 1 June and can trace defects that were undetectable until now. The test has already been shown to be successful in a clinical trial setting.

iStockiStockWe know that couples who are related by blood, such as cousins, run a greater risk of having a child with a cognitive impairment and/or genetic defect. They share more genetic material than couples who are not related. Cousins, for example, share 12.5% of the same DNA; brothers and sisters share 50%. If one of the pair is genetically predisposed towards a rare disorder, then there is a good chance that the other is as well. Until now, there was no test capable of detecting a rare defect in both.

Informed decision
The new test is explicitly meant to screen couples before pregnancy for hundreds of different genetic defects that are extremely rare in themselves, but that may pose a greater risk when a couple are related. Before, genetic testing was only carried out when the couple had already had a child with a particular defect so that they could take appropriate steps. Thanks to the new test, consanguineous couples can avoid having a child with a genetic defect before pregnancy. They can therefore take an informed decision about having children.

Maastricht UMC+’s Clinical Genetics department conducts genetic research and advises patients in the southeast region of the Netherlands. Every year, more than 5000 people and couples are referred to Maastricht for this purpose. Some of these referrals are couples related by blood. As of now, they are eligible for the new test. Maastricht UMC+ cooperates with Radboud University Medical Centre in Nijmegen, so couples being treated by the Clinical Genetics department there can also have the test done. The initial clinical trials have been promising. The test identified several couples as high risk and made it possible to discuss appropriate measures with them.