Single chromosome gives women stronger immune system than men
23 October 2011
New research on the role of microRNAs encoded on the X
chromosome seems to explain why women have stronger immune systems to
men and are less likely to develop cancer.
The research, led by Dr Claude Libert from Ghent University in
Belgium, focused on MicroRNA, tiny strains of ribonucleic acid which
alongside DNA and proteins, make up the three major macromolecules
that are essential for all known forms of life.
“Statistics show that in humans, as with other mammals, females
live longer than males and are more able to fight off shock episodes
from sepsis, infection or trauma,” said Libert. “We believe this is
due to the X chromosome, which in humans contains 10% of all
microRNAs detected so far in the genome. The roles of many remain
unknown, but several X chromosome-located strands of microRNA have
important functions in immunity and cancer.”
Dr Libert’s team proposes that the biological mechanisms of the X
chromosome have a strong impact on an individual’s genes, known as
genetic imprinting, which gives an immunological advantage to
females. To develop their hypothesis the team produced a detailed
map of all described microRNAs which have a role in immune functions
and cancer in both human and mouse X chromosomes.
“We believe this immunological advantage is due to the silencing
of X-linked genes by these microRNAs,” said Libert. “Gene silencing
and inactivation skewing are known mechanisms which affect X-linked
genes and may influence X-linked microRNAs in the same way.”
This genetic silencing leaves males at an immunological
disadvantage as a male has only one X-chromosome. The Y-Chomosone
contains fewer genes so if the genes involved in immunity are
silenced maternally the male is left with no compensating genetic
“How this unique form of genetic inheritance
influences X-chromosone linked microRNAs will be a challenge for
researchers for years to come,” concluded Libert, “not only from an
evolutionary point of view, but also for scientists investigating
the causes and cures of disease.”
Pinheiro. I, Dejager. L, Libert. C. X-chromosome-located
microRNAs in immunity: Might they explain male/female differences?
Bioessays, September, 2011, Wiley-Blackwell.
Klein. Implications of X-linked gene regulation for sex differences
in disease pathogenesis. Bioessays, September, 2011,