100 hereditary diseases before conception – simple and cheap
Recently organized in Redwood City (California), Counsel has developed a genetic test that allows expectant parents to determine the risk of transmitting to their child more than 100 different hereditary diseases. The cost of the test, amounting to $ 349, is already covered by several major insurance companies.
To date, researchers have identified the genetic causes of more than 1,000 rare hereditary diseases, but the scale of testing aimed at detecting such mutations is extremely limited due to the high cost of tests. Currently, most people planning to have a child are recommended to conduct a screening test for cystic fibrosis (chronic lung disease). More extensive testing is offered mainly to representatives of certain ethnic minorities, such as Ashkenazi Jews.
For relatively little money, Counsyl offers those who wish to spit into a special test tube and send it by mail to the company's address, where specialists will conduct extensive genetic screening. The diseases detected by the new test include such rare genetic diseases as cystic fibrosis, Tay-Sachs disease (early childhood amaurotic idiocy) and Pompe disease (generalized glycogenosis). People whose genome contains one copy of the mutant gene that causes the development of these diseases are usually healthy, but inheritance of two copies (one from the mother, the other from the father) is guaranteed to cause the development of the disease. As a rule, such hereditary diseases are incurable and often lead to disability and early death.
Monogenic (caused by a mutation of one gene) hereditary diseases in the United States are detected in 3-5 out of 1000 live-born children. According to the data provided by Counsel, 35-40% of people who have already been screened using the new test are carriers of at least one of the diseases they identify. In 0.6-0.8% of cases, both future parents are carriers of a mutant copy of a gene. At the same time, the probability of having a sick child is 25%, the probability of inheriting one copy of the mutant gene is 50%. Such married couples can contact a center that provides artificial insemination services, whose specialists will screen them for mutant genes before implanting embryos into the uterus. You can get pregnant naturally and then carry out prenatal genetic screening of the fetus, but this option is understandably worse. It's even worse to rely on chance.
The genetic variants detected by the new test are not new to medicine. Any of them can be identified either by an individual test or as part of some other screening. The novelty of the approach lies in the possibility of detecting more than 100 different diseases in one test.
The test is based on the technology of using an inversion molecular probe that binds certain small fragments of DNA, which allows their analysis to be carried out with a high degree of accuracy. According to Counsel's chief technologist Balaji S. Srinivasan, this week the company will publish the details of the methodology, as well as the level of reliability of the results obtained in a peer-reviewed journal. He also notes that in the future, Counsel plans to switch to a gene sequencing technique that allows decoding all nucleotides that make up genes.
Unfortunately, the test does not give a 100% guarantee that the newborn does not have any diseases detected by him, since with its help it is impossible to identify many internal and external factors that can disrupt the normal development of the embryo. In addition, not all mutations underlying the diseases detected by the new test have been identified to date. This means that even negative test results do not exclude the possibility of carrying a defective copy of a gene.
Experts predict that other companies specializing in genetic testing and research institutions, such as 23andMe, Navigenics, Baylor and the Mayo Clinic, will not stand aside and will soon begin to provide similar services, which may further reduce the cost of the test.
Evgenia Ryabtseva, Alexander Chubenko
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of TechnologyReview: New Test Screens Prospective Parents for 100-Plus Diseases.
04.02.2010