3/19/2006

Troubling times for embryo gene tests

AT THE age of 4, Doreen Flynn's first daughter, Jordan, was diagnosed with Fanconi anaemia, a rare genetic blood disorder that leaves people underweight and with a 700-fold greater chance of developing cancer. It is unlikely that Jordan will live past her early twenties.

Flynn and her husband wanted to have more children, partly because a bone-marrow transplant from a healthy sibling would be Jordan's best shot at survival. They decided to undergo pre-implantation genetic diagnosis, an IVF technique designed to ensure only healthy embryos are implanted. A Detroit-based lab, Genesis Genetics Institute, isolated two apparently disease-free embryos that would be bone-marrow matches for Jordan and implanted them at a hospital in Atlanta in early 2003. Julia and Jorjia were born 34 weeks later. Both have Fanconi anaemia.

Fortunately, reports of such errors connected to clinical genetic testing are extremely rare. Mark Hughes, the founder and chief clinician at Genesis, says that since the earliest days of his company 17 years ago, there have been only nine such instances out of several thousand tests conducted. "There is going to be an error rate in any diagnostics, and it's especially tricky in this instance," he says, because genetic testing relies upon identifying a very short DNA sequence among the large volume of DNA that comprises the human genome.

However, last week another case highlighted the potential costs of a lab or hospital getting a genetic test wrong. In what many are calling a "wrongful birth lawsuit", the Ohio Supreme Court upheld the right of Helen and Richard Schirmer to sue their healthcare provider, the Children's Hospital Medical Center in Cincinnati, for returning the wrong results of a fetal genetic test to diagnose trisomy 22, a genetic defect that causes severe mental and physical retardation. Their son, Matthew, was born with the condition in 1997.

Meanwhile, the diversity and popularity of genetic testing is skyrocketing. A recent survey by the OECD group of industrialised countries showed that the number of genetic tests carried out in these countries increased from 875,000 in 2000 to 1.4 million in 2002. There are now more than 900 distinct genetic tests in the US, compared with about 300 in 2002 – and that doesn't include the burgeoning number of "non-medical" hometesting kits sold to families over the internet.

This expansion is being driven both by a rapid growth in the number of genes discovered and advances in the technologies available to detect them.

In 2000, the US Centers for Medicare and Medicaid Services launched a notice of intent to create rules ensuring the quality of genetic testing, but difficulties in regulating the system have led to long delays. The OECD is attempting to develop similar guidelines for its member countries, which include the US, UK and much of Europe.

Troubling times for embryo gene tests

Pre-print from March 18 New Scientist

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