In the humanized mouse model under the conditions studied here, partial loss of cxcr4 in human T cells due to treatment with X4 - ZFNs provided selective pressure for either the evolution or emergence of a pre-existing single amino acid mutation in the V3 loop of the infecting X4 HIV - 1 strain that enabled it to use CCR5 as efficiently as CXCR4. (journals.plos.org)
Single amino acid mutations in mTOR are found in several types of human cancers, which confer constitutive activation of this autophagy negative regulator [10,11]. (f1000.com)
Assessing the evolutionary impact of amino acid mutations in the human genome Boyko, A. R., S. H. Williamson, A. R. Indap, J. D. Degenhardt et al. 2008. (nielsenlab.org)