Some Israeli couples with foetuses that tested positive for Gaucher disease, an inherited condition that can range from mild and treatable to severe, chose abortions, raising questions about the use of certain types of genetic screenings, a new study suggests.
The study authors also question the use of genetic screening for other kinds of mild hereditary disorders.
Disease often shows no symptoms
Gaucher disease (GD) includes three diseases caused by deficient activity of a certain enzyme. Common type 1 Gaucher disease often causes no symptoms and is usually not severe and can be treated, the researchers said.
According to the National Gaucher Foundation, the most common symptoms of the disease are enlarged livers and spleens; anaemia; reduced platelets that can result in easy bruising and clotting difficulties; bone "infarctions" that can lead to damage to the shoulder or hip joints; and a generalized "demineralization" of the bones, or osteoporosis. This can lead to spontaneous fractures.
Gaucher disease is relatively common in Ashkenazi Jews, who have been offered screening worldwide and in Israel since 1995, according to background information in the study.
Test doesn’t predict severity
But the use of this screening is controversial, because the test does not fully predict the severity of the disease. Even so, some couples decide to abort a fetus if it tests positive for Gaucher disease, the researchers noted in the Sept. 19 issue of the Journal of the American Medical Association.
In the study, a team led by Shachar Zuckerman of Shaare Zedek Medical Centre in Jerusalem analysed data from 10 Israeli medical centres that offered Gaucher disease screening. From January 1995 to March 2003, there were about 28 893 people screened at the centres. Of those, there were 83 GD carrier couples. The GD carrier frequency was 5.7 percent.
There were 82 couples at risk for children with type 1 GD. Seventy of the 82 couples (85 percent) were at risk for asymptomatic or mildly affected children, and 12 of the 82 couples (15 percent) were at risk for moderately affected children, the study found.
25% of foetuses aborted
Prenatal diagnosis was performed in 68 of 90 (76 percent) pregnancies, and pregnancies were terminated in four of 16 (25 percent) cases of foetuses with Gaucher disease. Of the four aborted foetuses, two were predicted to have asymptomatic, or mild GD, and two were predicted to have moderate disease.
The study found that there were far fewer pregnancy terminations among couples who, in addition to receiving genetic counselling, also had medical counselling with a Gaucher disease expert - one of 13 (eight percent) of pregnancies, compared with three of three (100 percent) among couples who did not receive medical counselling.
"With respect to the stated goal of carrier screening programs, the main practical outcome of GD screening was a 66 percent reduction in birth prevalence for moderate type 1 GD, for which the estimated frequency is 1 in 27,000, and a 15 percent reduction in the birth prevalence of asymptomatic or mild type 1 GD, for which the estimated frequency is 1 in 1,300. This was achieved through termination of pregnancy of fetuses either treatable or likely to be asymptomatic, and it is debatable whether this represents a true benefit," the study authors wrote.
They noted that the Israeli Medical Geneticists Association has recommended against Gaucher disease screening.
In an accompanying editorial in the journal, Dr. Ernest Beutler, of the Scripps Research Institute in La Jolla, Calif., said, "Not until clinicians and researchers better understand the factors that determine whether a patient homozygous for the N370S (GD) mutation will develop severe disease or none at all will screening for Gaucher disease become useful. Until then, screening for Gaucher disease will likely do more harm than good." - (Serena Gordon/HealthDay)
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