- Homozygous L-SIGN (CLEC4M) plays a protective role in SARS coronavirus infection. Chan, V.S., Chan, K.Y., Chen, Y., Poon, L.L., Cheung, A.N., Zheng, B., Chan, K.H., Mak, W., Ngan, H.Y., Xu, X., Screaton, G., Tam, P.K., Austyn, J.M., Chan, L.C., Yip, S.P., Peiris, M., Khoo, U.S., Lin, C.L. Nat. Genet. (2006)