The UMLS Metathesaurus and the Semantic Network (SN) were created in the absence of a comprehensive curated genomics terminology and before the recent quantitative and qualitative explosion of genomic knowledge. In this paper we evaluate the internal consistency of the SN's categories relevant to genomics and propose changes to improve its ability to express genomic knowledge. We evaluate the completeness of the SN with respect to genomic concepts by extracting genomics vocabulary from leading texts and databases of genomic information and comparing the extracted vocabulary to the SN. We propose corresponding extensions to the SN to fill identified gaps.