diff --git a/bin/filter_manifest.py b/bin/filter_manifest.py
new file mode 100644
index 00000000..555a607a
--- /dev/null
+++ b/bin/filter_manifest.py
@@ -0,0 +1,31 @@
+import os
+import sys
+import shutil
+import pandas as pd
+
+def __main__():
+    
+    manifest = sys.argv[1]
+    reads = sys.argv[2]
+    print("Input manifest file:", manifest)
+    print("Input read file: ", reads)
+
+    manifest_df = pd.read_csv(manifest, index_col=None, header=0, delimiter=",")
+
+    if reads != "PASS":
+        # process metadata
+        reads_df = pd.read_csv(reads, index_col=None, header=0, delimiter=",")
+        manifest_df = manifest_df[manifest_df['file_name'].isin(reads_df['file_name'].tolist())]
+
+        if manifest_df.empty:
+            sys.exit(404, "Manifest file is empty after filtering.")
+        
+        if len(reads_df[~reads_df['file_name'].isin([manifest_df['file_name'].tolist()])])>0:
+            print("The following file_name IDs where not found in manifest:")
+            print(reads_df[~reads_df['file_name'].isin([manifest_df['file_name'].tolist()])])
+            reads_df[~reads_df['file_name'].isin([manifest_df['file_name'].tolist()])].to_csv("not_found_GTEX_samples.txt", index=False)
+
+    # save final manifest file
+    manifest_df.to_csv("filtered_manifest.csv", sep=",", index=False) 
+
+if __name__=="__main__": __main__()
\ No newline at end of file
diff --git a/main.nf b/main.nf
index 8a381059..2574c807 100755
--- a/main.nf
+++ b/main.nf
@@ -277,18 +277,12 @@ if (params.download_from) {
         .set { accession_ids }
   }
   if(download_from('gen3-drs')){
-    // TODO - Reads parameter optional. If not provided use all data in manifest
-      Channel
-        .fromPath(params.reads)
-        .ifEmpty { exit 1, "Cannot find CSV reads file : ${params.reads}" }
-        .splitCsv(skip:1)
-        .map { file_name -> [file_name] }
-        .set { ch_gtex_gen3_reads }
+    ch_gtex_gen3_reads = params.reads ? Channel.fromPath(params.reads) : "null"
 
-      Channel
-        .fromPath(params.manifest)
-        .ifEmpty { exit 1, "Cannot find manifest file : ${params.manifest}" }
-        .set { ch_gtex_gen3_manifest }
+    Channel
+      .fromPath(params.manifest)
+      .ifEmpty { exit 1, "Cannot find manifest file : ${params.manifest}" }
+      .set { ch_gtex_gen3_manifest }
   }
   if(download_from('ftp')){
     Channel
@@ -368,6 +362,7 @@ if ( download_from('gen3-drs')) {
         .fromPath(params.genome_fasta)
         .ifEmpty { exit 1, "${params.genome_fasta} is not present" }
         .set {ch_genome_fasta}
+  filter_manifest_py = Channel.fromPath("${projectDir}/bin/filter_manifest.py",  type: 'file', followLinks: false)
 }
 
 if ( download_from('sra')) {
@@ -487,7 +482,29 @@ if ( download_from('gen3-drs')) {
     in2csv $manifest > \${filename}.csv
     """
   }
-  ch_gtex_gen3_manifest_csv.
+
+  process filter_manifest {
+    label "tiny_memory"
+    publishDir "${params.outdir}/process-logs/${task.process}/${file(file_name).baseName}", pattern: "command-logs-*", mode: 'copy'
+    publishDir "${params.outdir}", pattern: "*.txt"
+
+    input:
+    file(manifest) from ch_gtex_gen3_manifest_csv
+    file(reads) from ch_gtex_gen3_reads
+    each file("filter_manifest.py") from filter_manifest_py
+
+    output:
+    file("*.txt")
+    file("filtered_manifest.csv") into ch_gtex_gen3_filtered_manifest_csv
+
+    script:
+    optional_reads = params.reads ? "$reads": "PASS"
+    """
+    filter_manifest.py $manifest $optional_reads
+    """
+  }
+
+  ch_gtex_gen3_filtered_manifest_csv.
     .splitCsv(skip:1)
     .map { md5sum, file_name, obj_id, file_size -> [md5sum, file_name, obj_id, file_size] }
     .set { ch_gtex_gen3_ids }
diff --git a/nextflow.config b/nextflow.config
index cc35b99d..f51554ce 100755
--- a/nextflow.config
+++ b/nextflow.config
@@ -103,6 +103,9 @@ process {
   withName: 'in2csv' {
     container = 'quay.io/lifebitai/csvkit:1.0.5'
   }
+  withName: 'filter_manifest' {
+    container = 'quay.io/lifebitai/pcgr:python-base_1.0.0'
+  }
   withName: 'gen3_drs_fasp' {
     container = 'anczukowlab/lifebit-ai-fasp:v1.1'
   }