Question about the result of GO:BP analysis: only one or two gene related to one GO term

[Mancang-Yu]

Hi！This is my code run the GO:BP analysis:

group <- data.frame(gene=df_sig_up$gene,
                    group=df_sig_up$cluster)

Gene_ID <- bitr(df_sig_up$gene, fromType="SYMBOL", 
                toType="ENTREZID", 
                OrgDb="org.Mm.eg.db")

#构建文件并分析
data  <- merge(Gene_ID,group,by.x='SYMBOL',by.y='gene')

data_GO <- compareCluster(
  ENTREZID~group, 
  data=data, 
  fun="enrichGO", 
  OrgDb="org.Mm.eg.db",
  ont = "BP",
  pAdjustMethod = "BH",
  pvalueCutoff = 0.05,
  qvalueCutoff = 0.05
)
data_GO_sim <- clusterProfiler::simplify(data_GO)

data_GO_sim_gene1<-setReadable(data_GO_sim, OrgDb = org.Mm.eg.db, keyType="ENTREZID")

I found that there are many GO term enriched with only one or two geneID involved. I wonder if such results can be trusted?Or is there something wrong with my analysis?

[guidohooiveld]

Note that you applied the function simplify(), that removes redundant terms. Do the results in data_GO look fine? Thus, are all gene sets / GO categories comprised of at least 10 genes?