Venter’s achievement followed an earlier breakthrough in 2014, when Floyd Romesberg at Romesberg Lab in California succeeded in creating xeno nucleic acid (XNA), a synthetic alternative to DNA, using amino acids not found among the naturally occurring four nucleotides: adenine, cytosine, guanine a..

Source: https://prepareforchange.net/2019/01/26/synthetic-organisms-are-about-to-challenge-what-alive-really-means/