Heart-Defect Gene Is Located That May Cause Heart Defects
By ANTONIO REGALADO
Staff Reporter of THE WALL STREET JOURNAL
By scanning the DNA of a Dallas-area family, Texas doctors have pinned down a gene that can cause congenital heart defects.
The gene finding is already being used to screen parents who might be carriers, and could eventually lead to a simple treatment for expectant mothers, said researchers at the University of Texas, Southwestern Medical Center in Dallas, whose study was published Sunday in the online edition of Nature, a scientific journal.
Children with defects in the gene, known as GATA4, are born with holes connecting the chambers of their hearts. Known as septal defects, the holes can typically be patched up with surgery, but remain a leading cause of death in young children.
Researchers studied an extended Dallas family with a history of heart defects, said Deepak Srivastava, a pediatrician at UT Southwestern who was the senior author. After comparing the genetic makeup of family members with heart problems to those without, the researchers turned up the link to GATA-4. About one in 100 newborns has a congenital heart defect, about half of which are septal defects.
Mutations in the gene probably account for less than 5% of all septal defects, Dr. Srivastava said. However, children born with a defective version are certain to develop heart trouble, he said. Parents carrying a mutated version of GATA-4 have a 50% chance of passing it to their child.
The group says it hopes to genetically engineer mice with the gene defect, then begin testing batches of drugs and nutritional supplements to see if any cause the heart to form normally. The gene is the third found to cause septal defects.
The pace of such discoveries is accelerating rapidly because of the completion of the Human Genome Project, which has provided scientists a list of all human genes.
Heart conditions are a new area for genetic tests, where they could raise thorny ethical questions. Dr. Srivastava said members of the Dallas family had all been screened to learn if they are carriers. One woman who tested positive during the study went on to have a second child born with a heart defect, he said. The UT Southwestern doctors said they encouraged parents with a family history of heart defects to get tested for the gene.
At this stage, doctors are unlikely to recommend aborting a pregnancy, because the defects are routinely corrected via surgery. Such heart problems are usually caught during ultrasound examinations after a child begins showing symptoms, but genetic tests could help surgeons fix the defects earlier.
Recently, fertility experts have also begun using genetic tests to help families avoid specific congenital problems altogether. Embryos are made in the laboratory, tested, and only the genetically healthy ones are used to start a pregnancy.
The Dallas researchers plan to begin screening common drugs and supplements to see if taking them during pregnancy could prevent the heart problems. For instance, pregnant women take folic acid in order reduce the chance of having a child with spina bifida, a disease of the spine.
Write to Antonio Regalado at antonio.regalado@wsj.com
Updated July 7, 2003 12:28 a.m.
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