different results coming from biomart online and biomaRt R library
Sorry, this was my mistake in the last question. To search down the ontology, rather than just for the specific association with a term, biomaRt needs a different filter: 'go_parent_term'.

Try:

gene &lt;- getBM(attributes = c('external_gene_name'), filters = 'go_parent_term', values = 'GO:0030098', mart = ensembl)