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Scale, Toll of Gene Birth Defects Vast, Study Finds

Most cases are preventable, but millions of children die early or are disabled. Testing and nutrition could help poor nations.

January 31, 2006|Thomas H. Maugh II | Times Staff Writer

Nearly 8 million children each year are born with genetic birth defects, and fully 70% of them could be prevented or mitigated, according to the first worldwide study commissioned by the March of Dimes.

With most receiving no treatment, at least 3.3 million of the children die before the age of 5 and 3.2 million are disabled for life, said the study, which was released Monday.

"Our report identifies for the first time the severe and previously hidden global toll of birth defects," said Dr. Jennifer L. Howse, president of the March of Dimes, based in White Plains, N.Y. "This is a serious, vastly unappreciated and underfunded public health problem."

The incidence ranges from a high of 82 defects per 1,000 births in Sudan to a low of 39.7 per 1,000 in France. More than 94% of birth defects and deaths occur in middle- and low-income countries, said Dr. Christopher P. Howson of the March of Dimes, a coauthor of the report.

The authors believe that hundreds of thousands more birth defects occur because of environmental factors, such as congenital rubella and syphilis, iodine deficiency and fetal alcohol syndrome. But Howson said meager data were available to document the incidence of those problems.

Fetal alcohol syndrome, in particular, "is a huge problem, but there are countries that don't monitor it or recognize it," said Dr. Arnold Christianson of the University of the Witwatersrand in Johannesburg, South Africa, another coauthor.

Five common birth defects accounted for about 26% of the total in 2001, the most recent year for which data were available. They included congenital heart defects (1 million cases); neural tube defects, such as spina bifida (324,000 cases); the hemoglobin disorders thalassemia and sickle cell disease (308,000 cases); Down syndrome (217,000 cases); and glucose-6-phosphate dehydrogenase deficiency (177,000 cases).

"This is an extraordinary toll," Howson said. "People are going to ask, 'Why isn't more being done to address this problem?' "

Among the reasons for the higher incidence of birth defects in developing countries, the report concluded, are the increasing number of older women having babies, the higher frequency of marriages between blood relatives and poor nutrition among pregnant women.

A large fraction of the at-risk population also lives in the "malaria belt," where that disease is endemic. Many people there carry a gene for an inherited disease, such as sickle cell, thalassemia, or G6PD deficiency, that protects against malaria but can produce birth defects when carriers mate.

The incidence of birth defects and disability can be sharply reduced in developing countries, the report concluded.

"Experience from high-income countries shows that overall mortality and disability from birth defects can be reduced by up to 70% if the recommendations in this report were broadly implemented," Christianson said.

Some solutions are relatively simple, such as adding folic acid and iodine to the food supply and including a rubella shot in vaccination programs.

Folic acid supplementation in enriched flour, for example, costs about a penny per person per year. In 2000, Chile began adding folic acid to flour and saw a 40% drop in neural tube defects.

Genetic testing for defects such as phenylketonuria (a digestive disorder) and thalassemia can be relatively cheap -- as little as $5 per test.

The report noted that Iran began testing engaged couples for the thalassemia gene in 1997 because of the growing cost of care. By 2001, 10,298 at-risk couples had been identified and counseled, and thalassemia births had dropped 70%.

Many birth defects, including some heart defects, clubfoot and cleft lip and palate, can be corrected by surgery. Too often, however, newborns are discharged from the hospital or birthing center without anyone being aware of their problems.

"No child should leave a hospital or clinic who has not been examined by a provider who has been trained to recognize and diagnose birth defects," Howson said. "There are effective ways to care for a lot of these birth defects and save [the children] from unnecessary death and disability."

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