Hershey, Pa. -- Premature infants may be more prone to respiratory distress syndrome because of genetic variations. Researchers have provided evidence that certain genetic variations in the surfactant protein gene appear with higher frequency in the (RDS) population.
"This suggests an association between these genetic variations and RDS, and this is currently being explored further," says Joanna Floros, professor of cellular and molecular physiology and pediatrics in Penn State's College of Medicine. "Therefore, it is possible that the surfactant proteins are some of the factors that contribute to RDS. In other words, certain genetic alterations in the surfactant protein genes may predispose to, or protect from, RDS."
All babies need surfactant for normal lung function. When there is not enough surfactant produced, babies face the risk of developing RDS.
Floros' paper, titled, "SP-A and SP-B Polymorphisms in RDS," is scheduled to be published in the February issue of the Journal of Pediatric Research. The research is funded by the National Institutes of Health.
"There are four surfactant proteins that coisolate with surfactant, and three of them play a role in the function of surfactant. A variation in the A and B genes appears with higher frequency in babies with RDS," says Floros. "Babies born prematurely that have this genetic background have a higher chance of RDS."
About 10 percent of all prematurely born infants, or 1 percent of all births, develop breathing problems or RDS. In the United States each year 40,000-50,000 infants develop RDS, and roughly one-tenth of them will develop severe complications and/or die.
Surfactant is produced beginning in the final trimester of human gestation. The longer the gestation, the more surfactant that is produced. This means the more premature a baby is, the less surfactant that has been produced and the higher the risk of RDS. However, the amount of surfactant produced during fetal development differs among babies and that may explain why some babies born prematurely develop RDS and others do not.
Floros took blood samples from premature babies with RDS and from those who did not develop the disease for the study. This study was limited to babies who were greater than 28 weeks of gestation.
"It is not likely that RDS is caused by one gene. This is a highly complex disease. It is hypothesized that the disease comes as a result of several disease-causing genes and their interactions either among themselves or with modifier genes that affect, for example, the severity of the condition," says Floros.
She adds that since a number of different factors may result in RDS, it is likely that a number of disease subgroups exist and that the underlying genetic factors of each subgroup may differ or overlap with those of another RDS subgroup. To identify each disease subgroup, Floros and her research team use clinical characteristics. Studying individuals with similar clinical characteristics is important, she says, because it can help identify factors that may cause disease in the particular subgroup. This knowledge in turn will help identify points along the disease pathway where the Penn State researcher can intervene therapeutically.
The study of this disease with multiple causes requires the cooperation and collaboration from experts from several fields. Floros has established a network of clinical centers around the country and abroad to collect specimens from appropriate patient groups to continue this work.