MDA5 deficiency

MDA5 deficiency is a disorder of the immune system (immunodeficiency) that leads to recurrent, severe infections of the lungs and airways (respiratory tract) beginning in infancy. These infections are most frequently caused by rhinovirus (the virus that causes the common cold). Respiratory syncytial virus (RSV) and the influenza (flu) virus may also cause recurrent infections in affected individuals. While infection by these viruses is common in all children, it usually causes mild symptoms and lasts only a short time before being cleared by a healthy immune system. In contrast, individuals with MDA5 deficiency frequently require hospitalization due to the severity of the symptoms caused by the infection. Repeated infections can contribute to chronic lung disease.

Infections usually become less frequent with age in people with MDA5 deficiency, as the body's immune system matures and develops other mechanisms for fighting viruses.