We studied a child with life-threatening and recurrent respiratory tract infections, caused by multiple viruses including rhinovirus, influenza virus, and respiratory syncytial virus (RSV). We identified in her a homozygous missense mutation in IFIH1 that encodes MDA5 by Whole Exome Sequencing. MDA5-deficiency is a novel inborn error of innate immunity that results in impaired dsRNA-sensing, reduced IFN induction, and susceptibility to the common cold virus.

We studied a child with life-threatening and recurrent respiratory tract infections, caused by multiple viruses including rhinovirus, influenza virus, and respiratory syncytial virus (RSV). We identified in her a homozygous missense mutation in IFIH1 that encodes MDA5 by Whole Exome Sequencing. MDA5-deficiency is a novel inborn error of innate immunity that results in impaired dsRNA-sensing, reduced IFN induction, and susceptibility to the common cold virus.