Friday, December 07, 2012

Cystic Fibrosis Screening

Approximately 1 in 25 Ashkenazi Jews are carriers of Tay-Sachs disorder which is a really nasty genetic disorder that kills children who have inherited two copies of the Tay-Sachs variant of the gene from their parents by the age of four.

This disease does not effect many kids anymore though

of the 10 babies born in North America in 2003 with Tay-Sachs, not a single one was Jewish.

Figures from Israel paint a similar picture.

According to Prof. Joel Zlotogora, who heads the Health Ministry's Department of Community Genetics, just one baby was born with Tay-Sachs in Israel in 2003. Insofar as is known, not a single baby in Israel was born with Tay-Sachs last year,(2004)

Israel almost ten years ago pretty much eradicated a really nasty genetic disease. This has been done by screening people so that they know they are carriers. If they find out early in a relationship that their partner is also a carrier people tend to decide they are incompatable. IVF techniques allow testing of preimplantation embryos for certain genetic disease before implantation. Finally 'the general public in Israel is advised to carry out, at the expense of the state, genetic tests to diagnose the disease before the birth of the baby. In the event an unborn baby is diagnosed with Tay-Sachs, the pregnancy is usually terminated'.

The Cystic Fibrosis variant of the gene is carried by 1 in 19 Irish people. This is the highest rate in the world. CF is an unpleasant disease but not nearly as unpleasant as Tay-Sachs. It is however the most common genetic disorder in Ireland and one that is more common than Tay-Sachs, which screening eradicated nearly a decade ago.

75,554 children born in Ireland during 2009. Testing newborns would be unfair for reasons of consent but a genetic test for CF could be offered to adults. Genetic carrier test costs a bit over 100 euro (but the costs has been dropping exponentially for the last several years). Testing in bulk means this screening could come in at under 7 euro million a year. Much of the cost in testing involves collection and processing of samples. This means other less common genetic disorders could be screened for at little extra cost.

A bed in an Irish hospital costs €910 per day. This is semi private room and I believe CF rooms need to be more isolated than this. That is €332150 per year. For the 20 beds in the St Vincents unit that costs (roughly) 6.5 million per year. The cost of screening every 18 year old for CF is roughly that of running one ward in St Vincents for a year.

This cost benefit analysis of screening for CF of one ward ignores all the other medical costs involved in CF but worse it ignores the suffering of the 35-40 children (one in 1,461) born with the disorder every year. The termination of fetus' with CF would not be supported in Ireland. CF compared to Tay-Sachs is a mild disorder and Irish people have a different opinion on termination to Israeli's. But with voluntary screening CF cases would significantly reduce just from partner selection alone.

I think at least a cost benefit analysis and a debate on the morality of genetic screening of the general population should take place.

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