Screening all pregnant women for a rare but fatal genetic disease is too expensive, researchers say in a new report that adds to a recent controversy about whether genetic tests are worth the cost.

Babies with the severe form of the disease - known as spinal muscular atrophy or SMA - become too weak to breathe effectively within months of birth. They usually die as toddlers after a futile battle against lung infections.

While scientists can already screen for SMA, allowing parents to seek an abortion or decide against having children, doctors are split on whether or not to recommend routine screening due to cost concerns.

The new study puts the price squarely on the table: $5 million for each case of SMA avoided by prenatal screening.

“We found it to be too expensive,” said Dr. Sarah Little of Massachusetts General Hospital, who worked on the study. She added that the value for money was a tiny fraction of what is generally considered acceptable by health economists.

While a genetic test for SMA costs just under $500, more than 12,500 women would have to be screened to prevent one case of SMA, which affects only about 1 in 10,000 newborns.

The results bolster guidelines from the American College of Obstetricians and Gynecologists, which recommends that only parents with a family history of SMA get screened.

However, another professional association, the American College of Medical Genetics, was not impressed with the study, which was published in the American Journal of Obstetrics and Gynecology.

“They came to the wrong conclusion because they used the wrong tool to do the evaluation,” said Michael Watson, executive director of the American College of Medical Genetics, which recommends universal screening for SMA.

The team used the standard method of calculating cost-effectiveness, which naturally favors screening for diseases such as cystic fibrosis in which patients live long lives and require expensive treatment.

When patients die young, in contrast, they don’t incur a lot of expenses, and so the dollar value of preventing such diseases is smaller.

“It’s just not a practical approach,” said Watson, adding that “we could save a ton of money in the US if everybody died.”

While Little agreed the analysis was not ideal, she said cost was an important piece of information in policy making.

The SMA Foundation, a patient advocacy group, declined to comment on the new findings.

In an editorial accompanying the report, health economist Scott Grosse, of the Centers for Disease Control and Prevention, said it was still too soon to judge the value of screening for SMA.

In an e-mail to Reuters Health, he said: “The increasing number of tests for rare genetic diseases presents both opportunities and challenges. We do not have a national consensus on the criteria to use in deciding which genetic tests should be routinely offered.”

SOURCE: American Journal of Obstetrics and Gynecology, March 2010.