Science writer Carl Zimmer of The Loom has done the count and arrived at 18,308 genes in the human genome.
The pie shows that we’re now down to just 18,308 genes. That’s over 8,000 genes fewer than six years ago. Many sequences that once looked like full-fledged genes, capable of generating a protein, now don’t make the grade. Some genes turned out to be pseudogenes–vestiges of genes that once worked but have been since wrecked by mutations. In other cases, DNA segments that appeared to be parts of separate genes have turned out to be part of the same gene.