The ENA Cross-Reference Search service holds cross-references to a number of external data resources linked to ENA records. GGBN has now become one of these resources, currently providing over three million GGBN-ENA crossrefs. By using the relationships between biological material records stored in GGBN, not only can the direct physical resource be cited, but also all derivatives, e.g., DNA, tissue, and specimen. ENA provides a Xref API for programmatic access. GGBN is currently working on its own API.

Parent enrichment
GGBN records are connected to 1.5 million unique ENA/NCBI numbers. These connections are enriched by using known relationships between biological material records. This enrichment is only done upwards, e.g. if an ENA number is related to a DNA sample, both its parent tissue and specimen record will inherit this connection. While a known connection between an ENA number and a specimen record is NOT transferred to tissue and or DNA samples, that are derived from that specimen.

