Genetic differences between the sexes mean newborn baby girls are less likely to fall ill with acute infections than newborn boys, a new study by researchers here has found.
The study led by scientists at the Royal College of Surgeons in Ireland and supported by researchers in Trinity College Dublin, focused on the differences between chromosomes in boys and girls.
Girls have two copies of the X chromosome, while boys only have one and it is this chromosome that has more of the genes involved in immunity.
According to the researchers, in females these immune genes have a higher level of expression, making them more capable of defeating acute infections.
In particular the study looked at the level of a factor called IRAK1 in the umbilical cord blood of newborns.
The gene and protein expression of IRAK1 was found to be higher in girls and this could be part of the reason why female infants have a better immune response than newborn boys.
The findings go some way towards explaining why it is that females seem to have a survival advantage over males, particularly during the newborn period.
"The phenomenon of female neonates being hardier than their male counterparts is well recognised," said Professor Catherine Greene, Associate Professor of Clinical Microbiology at RCSI who was the senior author on the paper.
"This research shows this is due to a fundamental genetic advantage which may also contribute to more effective responses to infection and disease throughout the human lifecycle."
The study, published in the journal Pediatric Research, also suggests that something similar may be occurring in babies born prematurely, where the differences between sexes could be even more marked.
