An inexpensive genetic test has been developed that can detect 448 genetic childhood diseases. The makers of the test are hoping to expand this to 580 conditions within the next six months and the Beyond Batten Disease Foundation, which funded the National Center for Genome Resources research hopes that the new universal screening process will be available commercially within a few years.
Presented in the January issue of the journal Science Translational Medicine, the test detects disease-causing recessive genes in one person and whether they are shared by his or her partner. Possible ailments that may be detected by this process include cystic fibrosis and Batten Disease.
Each person has two copies of most genes, one passed down from each parent. If both copies are recessive for a particular disease, the person will suffer from the disorder. On the other hand, if only one copy of the gene is recessive, the person becomes a carrier – although he or she does not contract the illness, it may be passed down to his or her offspring. Therefore, there is a 1 in 4 possibility that two parents with the same recessive gene will conceive a child with the ailment. According to the Beyond Batten Disease Foundation website, “the average person carries 2.8 gene mutations.”
The development of the new test was inspired by Craig Benson, the CEO of a biotechnology company in Texas. After his 5-year-old daughter Christiane was diagnosed in 2008 with Batten Disease, a rare, fatal genetic disorder caused by the inheritance of a particular recessive gene from both of the parents, Benson founded the Beyond Batten Disease Foundation to develop a treatment or cure. He also commissioned the new genetic test to screen for development of genetic disorders. Clinical trials for the new technology are expected to start in the fall.
The screening works by screening 7717 regions from 437 “target” genes instead of examining the entire human genome. This makes the process far less expensive, at around $500 per test. “These technologies are immensely powerful and they are reducing the cost of genome analysis thousands of fold,” said Dr. Stephen Kingsmore, the senior study author, in an article by the Toronto Star. “What we’ve done in this paper is to apply that technology for the first time to something that which would be a routine doctor’s test.”
At the moment, only a few genetic diseases such as Tay-Sachs and Down’s Syndrome are typically screened and usually in high-risk populations. Screening, especially in Canada, the US, and Israel, has resulted in a 90 per cent decline in Tay-Sachs among Ashkenazi Jews (who had a higher risk of being carriers for the disease) since the process was introduced about 40 years ago. This reduction was achieved through a combination of pre-natal screening (and sometimes abortion) and in-vitro fertilization. The Orthodox Jewish organization Dor Yeshorim also provided a service telling possible couples, based on genetic tests, whether they would be at risk of conceiving a baby afflicted with the disease and some organizations discourage marriage between couples likely to conceive a child with Tay-Sachs.
It is “normal for everyone to carry three or four catastrophic diseases in (their) genome,” Jakki Jeffs of Alliance for Life Ontario, told The Interim. “Seventy-five per cent of the time they are not going to pass on the disease.”
Jeffs noted that, “We are often given the negative side of things.” Good intentions of easing the lives of parents and potential sufferers are leading to “quality control” of the child, she explained. “We’re not looking at eradicating the disease (but) the people that might have it,” said Jeffs. Eventually, “if you have this test…maybe the state would say you really shouldn’t become pregnant because that child will cost the state.”
Jeffs recounts that, although amniocentesis was initially supposed to help parents and doctors prepare for caring a child with Down’s Syndrome, studies indicate that 90 per cent of couples will nevertheless abort it. Jeffs is concerned that parents who employ pre-natal genetic testing would abort the unborn child if it has a genetic disease, especially considering that for many of the ailments, there is no cure. “Given…a life-friendly environment…it might be different,” yet, to Jeffs, it seems to be “all part of the eugenic environment we (are) living in at the time.”