Implication of new genetic technologies on pre-pregnancy screening and prenatal testing 4 th Annual Obstetric Malpractice Conference David Amor 22 nd June 2012 VCGS is a not for profit subsidiary of Murdoch Childrens Research Institute and the main provider of clinical and pathology genetics services in Victoria
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Implications of New Genetic Technologies on Pre-pregnancy Screening and Prenatal Testing
Dr David Amor, Director, from Victoria Clinical Genetics Service has presented at the Obstetric Malpractice Conference. If you would like more information about the conference, please visit the website: http://bit.ly/10xh1iO
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Implication of new genetic technologies on pre-pregnancy screening and prenatal testing
4th Annual Obstetric Malpractice Conference
David Amor
22nd June 2012
VCGS is a not for profit subsidiary of Murdoch Childrens Research Institute and the main provider of clinical and pathology genetics services in Victoria
All couples hope for a healthy baby, however human
reproduction is hazardous
• 4% of all babies are born with a congenital abnormality or genetic disorder that is evident at birth
• Most people have at least one recognised genetic disease
• All people are born with a genetic predisposition to various medical problems
• Every genome contains 50-100 variants that are expected to cause genetic disease
• AR diseases individually rare but collectively common
• >1000 known recessive genes (many more unknown)
• All people have some recessive genes
• Many variants of uncertain significance
Recessive genetic screening in Australia
In Australia, the main single gene conditions for which pre-pregnancy genetic carrier screening is undertaken are:
• Haemoglobinopathies (thalassaemia)
• Autosomal recessive diseases more common in the Ashkenazi Jewish community including Tay-Sachs disease
• Cystic fibrosis (conflicting guidelines and policy)
The ‘long tail’ of recessive genetic disease
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Disease frequency
‘Counsyl’ genetic test
• Microarray-based approach
• Just test for specific known mutations
• Cost $350-$500
• Screens for 105 diseases (mostly rare)
• Substantial risk of false negative results
• Risk of false positive results
• 1 in 4 people receive abnormal result
New York Times January 29, 2010
“Firm Brings Gene Tests to Masses”
• A Silicon Valley start-up is making the bold claim that it can help eradicate more than 100 diseases by alerting parents-to-be who have the carrier genes.
• Counsyl is selling a test that it says can tell couples whether they are at risk of having children with a range of inherited diseases.
• Once informed, couples can take steps like using IVF with genetic testing of embryos, to avoid bearing children who would have the diseases.
“As a genetic counselor, I’ve been waiting for this for a really long time,”- Elena Ashkinadze genetic counselor.
• But some experts say the company’s Web site overstates the case. The company calls its product the Universal Genetic Test, for example, even though there are thousands of genetic diseases, not just the 100 Counsyl tests detect.
“Everyone hopes there is a test that will provide a perfect baby, but the reality is that that single magic bullet doesn’t exist,”
- Dr. Joe Leigh Simpson, a geneticist and obstetrician.
• Some experts say that such screening could save countless parents from heartache, and society from the millions of dollars it can cost to care for even one severely ill person over a lifetime.
• But some experts foresee new issues. So many people would be carriers for at least one disease that genetic counselors might be overloaded. Some critics, meanwhile, say such testing is a step toward designer babies.
Next generation sequencing approach
• Low cost (analytical cost $400)
• Test whole sequence of 437 (or more) genes
• All people will receive abnormal result therefore need to test both partners
• Interpretation of many results difficult
• Reliant on existing databases that are known to contain inaccuracies