Before revision:  At the same time there is little or no evidence for protein expression for genes that have appeared since primates or that do not have any protein-like features or conservation. Based on our results we describe a set of 2,001 genes that have no protein features and poor conservation, or have ambiguous annotations in gene or protein databases.
After revision:  At the same time there is little or no evidence for protein expression for genes that have appeared since primates or that do not have any protein-like features or cross-species conservation. We identify 19 non-protein like features such as weak conservation, no protein-like features or ambiguous annotations in the major databases that are indicators of low peptide detection rates. We use these features to describe a set of 2,001 genes that have no protein features and poor conservation, or have ambiguous annotations in gene or protein databases.