diff --git a/conf/czbiohub_aws.config b/conf/czbiohub_aws.config
index d20b405..71d1a9b 100644
--- a/conf/czbiohub_aws.config
+++ b/conf/czbiohub_aws.config
@@ -61,6 +61,8 @@ params {
   fc_group_features = 'gene_id'
   fc_group_features_type = 'gene_type'
 
+  trim_pattern = '_+S\\d+'
+
   // GENCODE GTF and fasta files
   genomes {
     'GRCh38' {