sentences:  Efforts to engineer a more potent IFNα2 elicited a cellular response similar to IFNβ, suggesting that the affinity of type I IFNs for IFNAR has an important role in regulating the downstream response.Human IFNAR1 and IFNAR2 genes are located on chromosome 21q22.1.IFNAR1 is the low affinity subunit, originally cloned in 1990, and is composed of four fibronectin type II-like (FNII-like) subdomains, termed SD1-4.