A recent article published in The Journal of Experimental Medicine has identified a rare sequence variant that results in susceptibility to the common cold. A child with recurrent respiratory tract infections was subjected to whole-exome sequencing of her genome along with sequencing analysis of viral samples she was infected with. Viral sequencing indicated frequent infection with unrelated serotypes of human rhinovirus (the common cold). Whole exome sequencing analysis uncovered a single homozygous missense mutation in the IFIH1 gene, which is an extremely rare variant.
IFIH1 encodes the MDA5 protein. Mouse models with defective of MDA5 have previously been shown to be defective in detecting viral genetic material. Cell culture modelling suggests that this particular variant results in a dysfunctional MDA5 protein that cannot recognize human rhinoviruses. This indicates MDA5 has a key role in preventing human rhinovirus infections.
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