Specicide -- the deliberate extinction of an entire species -- could be engineered by exploiting the biology of selfish genetic elements. These are segments of genetic material found in the genomes of all organisms; they contribute nothing to the well-being of their hosts, but simply proliferate themselves. And proliferation is something they excel at. A feature of all selfish genetic elements is that they cheat at Mendel's rules of inheritance and so have better odds for getting into eggs and sperm than regular genes do. As a result, a selfish genetic element can spread through a population extremely fast -- far faster than a regular gene -- even if it is harmful to its host.
... (The risk to us from this technology is negligible. Even supposing an extinction gene appeared in humans — by accident or by malice — it would take thousands of years for extinction to be effected. During this time, it is inconceivable the gene's spread would go unnoticed; once noticed, it could easily be stopped.)
I really think the paragraph in parentheses should have appeared higher in the article! So this particular technique won't be used to wipe out humans. Phew.