Genetics may be a risk factor in premature infants who develop problems in their lungs as a result of not reaching normal gestational age, according to a study at Yale School of Medicine.
The three most common medical problems, and which also are responsible for most fatalities at this age, are intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), and bronchopulmonary dysplasia (BPD).
Vineet Bhandari, assistant professor in the Department of Pediatrics and lead author of the study, said the primary risk factor for these complications is immaturity of the organs followed by changes in blood flow to the brain and gut, exposure of the lung to mechanical ventilation, and high concentrations of oxygen. Genetics now join the list of risk factors for BPD.
“This is the first study to show that genetic factors are a significant component of BPD and may herald new paradigms for understanding the pathophysiology and treatment of this condition,” he said.
The researchers analyzed data retrospectively for 450 twin pairs from four hospitals. The average gestational age was 29 weeks and the average weight was, 1286 grams, or about 2.8 pounds. They also analyzed a sub-group of twins for which they had zygosity data. This group included 63 monozygotic twin pairs, which share 100 percent of their genome, and 189 dizygotic twin pairs, which share about 50 percent of their genome.
Bhandari said the researchers were unable to isolate and quantify the genetic components of IVH or NEC, but BPD occurred in 29 percent of either one or both of the monozygotic and 23 percent of the dizygotic twin pairs. After controlling for known contributing factors to BPD, genetic factors accounted for 53 percent of the variance in liability for BPD.
“Incremental improvements in the outcome of premature neonates in the future will likely depend on our ability to identify these genetic components and to target specific therapies,” he said.
Pediatrics 117: 1901-1906 (June 2006)