[6] Nitric oxide synthase is expressed in epithelial cells of the liver, lung and bone marrow.

[citation needed] Nitric oxide is a reactive free radical mediating in neurotransmission, antimicrobial and antitumoral activities.

[citation needed] In mice, the function of Nos2 in immunity against a number of viruses, bacteria, fungi, and parasites has been well characterized, whereas in humans the role of NOS2 has remained elusive and controversial.

They lack the gene encoding nitric oxide synthase 2 (Nos2) and are susceptible to murine CMV infection.

Whole-exome sequencing on genomic DNA from his blood showed he had homozygous variants in five genes.