diff --git a/.gitignore b/.gitignore
index f9bf2cc..c6e9902 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@ virheat/__pycache__/**
 virheat.egg-info/**
 build/**
 venv/**
+test.py
diff --git a/README.md b/README.md
index 934e018..aba7667 100644
--- a/README.md
+++ b/README.md
@@ -28,13 +28,8 @@ pip install virheat
 ```shell
 git clone https://github.com/jonas-fuchs/virHEAT
 cd virHEAT
-```
-and then install virHEAT with:
-```shell
 pip install -r requirements.txt
-```
-or:
-```shell
+# or
 pip install .
 ```
 That was already it. To check if it worked:
@@ -55,21 +50,20 @@ usage: 	virheat <folder containing vcfs> <output dir> -l or -g [additional argum
 
 ```
 positional arguments:
-  input                 folder containing vcf (and tsv) files and output folder
+  input                 folder containing input files and output folder
 
-optional arguments:
+options:
   -h, --help            show this help message and exit
   -l None, --genome-length None
                         length of the genome (needed if gff3 is not provided)
   -g None, --gff3-path None
                         path to gff3 (needed if length is not provided)
-  -a gene, --gff3-annotations gene
-                        annotations to display from gff3 file (standard: gene)
-  -t 0, --threshold 0   display frequencies above this threshold
+  -a [gene ...], --gff3-annotations [gene ...]
+                        annotations to display from gff3 file (standard: gene). Multiple possible.
+  -t 0, --threshold 0   display frequencies above this threshold (0-1)
   --delete, --no-delete
-                        delete mutations with frequencies present in all
-                        samples (default: True)
-  --sort, --no-sort     sort alphanumerically (default: False)
+                        delete mutations that are present in all samples and their maximum frequency divergence is smaller than 0.5 (default: True)
+  --sort, --no-sort     sort sample names alphanumerically (default: False)
   --min-cov 20          display mutations covered at least x time (only if per base cov tsv files are provided)
   -v, --version         show program's version number and exit
 ```
diff --git a/virheat/__init__.py b/virheat/__init__.py
index e841665..bf5eead 100644
--- a/virheat/__init__.py
+++ b/virheat/__init__.py
@@ -1,3 +1,3 @@
 """plot vcf data as a heatmap mapped to a virus genome"""
 _program = "virheat"
-__version__ = "0.5.2"
+__version__ = "0.5.3"
diff --git a/virheat/command.py b/virheat/command.py
index 963f4cc..74481ff 100644
--- a/virheat/command.py
+++ b/virheat/command.py
@@ -52,9 +52,11 @@ def get_args(sysargs):
         "-a",
         "--gff3-annotations",
         type=str,
+        action="store",
         metavar="gene",
-        default="gene",
-        help="annotations to display from gff3 file (standard: gene). Multiple possible (comma seperated)"
+        nargs="*",
+        default=["gene"],
+        help="annotations to display from gff3 file (standard: gene). Multiple possible."
     )
     parser.add_argument(
         "-t",
@@ -62,19 +64,19 @@ def get_args(sysargs):
         type=float,
         metavar="0",
         default=0,
-        help="display frequencies above this threshold"
+        help="display frequencies above this threshold (0-1)"
     )
     parser.add_argument(
         "--delete",
         action=argparse.BooleanOptionalAction,
         default=True,
-        help="delete mutations with frequencies present in all samples"
+        help="delete mutations that are present in all samples and their maximum frequency divergence is smaller than 0.5"
     )
     parser.add_argument(
         "--sort",
         action=argparse.BooleanOptionalAction,
         default=False,
-        help="sort alphanumerically"
+        help="sort sample names alphanumerically"
     )
     parser.add_argument(
         "--min-cov",
@@ -120,6 +122,8 @@ def main(sysargs=sys.argv[1:]):
     # define relative locations of all items in the plot
     n_samples = len(frequency_array)
     n_mutations = len(frequency_array[0])
+    if n_mutations == 0:
+        sys.exit("\033[31m\033[1mERROR:\033[0m Frequency array seems to be empty. There is nothing to plot.")
     if n_samples < 4:
         genome_y_location = 2
     else:
@@ -134,8 +138,7 @@ def main(sysargs=sys.argv[1:]):
         if gff3_ref_name not in reference_name and reference_name not in gff3_ref_name:
             print("\033[31m\033[1mWARNING:\033[0m gff3 reference does not match the vcf reference!")
         genome_end = data_prep.get_genome_end(gff3_info)
-        annotation_list = args.gff3_annotations.split(",")
-        genes_with_mutations, n_tracks = data_prep.create_track_dict(unique_mutations, gff3_info, annotation_list)
+        genes_with_mutations, n_tracks = data_prep.create_track_dict(unique_mutations, gff3_info, args.gff3_annotations)
         # define space for the genome vis tracks
         min_y_location = genome_y_location + genome_y_location/2 * (n_tracks+1)
     elif args.genome_length is not None:
@@ -159,11 +162,12 @@ def main(sysargs=sys.argv[1:]):
     plotting.create_heatmap(ax, frequency_array, cmap_cells)
     mutation_set = plotting.create_genome_vis(ax, genome_y_location, n_mutations, unique_mutations, genome_end)
     if args.gff3_path is not None:
-        # distinct colors for the genes
-        cmap_genes = plt.get_cmap('tab20', len(genes_with_mutations))
-        colors_genes = [cmap_genes(i) for i in range(len(genes_with_mutations))]
-        # plot gene track
-        plotting.create_gene_vis(ax, genes_with_mutations, n_mutations, y_size, n_tracks, genome_end, min_y_location, genome_y_location, colors_genes)
+        if genes_with_mutations:
+            # distinct colors for the genes
+            cmap_genes = plt.get_cmap('tab20', len(genes_with_mutations))
+            colors_genes = [cmap_genes(i) for i in range(len(genes_with_mutations))]
+            # plot gene track
+            plotting.create_gene_vis(ax, genes_with_mutations, n_mutations, y_size, n_tracks, genome_end, min_y_location, genome_y_location, colors_genes)
     plotting.create_axis(ax, n_mutations, min_y_location, n_samples, file_names, genome_end, genome_y_location, unique_mutations, reference_name)
     plotting.create_colorbar(args.threshold, cmap_cells, min_y_location, n_samples, ax)
     plotting.create_mutation_legend(mutation_set, min_y_location, n_samples)
diff --git a/virheat/scripts/data_prep.py b/virheat/scripts/data_prep.py
index ab2bd20..813776e 100644
--- a/virheat/scripts/data_prep.py
+++ b/virheat/scripts/data_prep.py
@@ -66,7 +66,7 @@ def read_vcf(vcf_file):
     for key in header[0:6]:
         vcf_dict[key] = []
     # functional effect
-    vcf_dict["TYPE"] = []
+    vcf_dict["MUT_TYPE_"] = []
     # info field
     for line in lines:
         for info in line[7].split(";"):
@@ -80,13 +80,13 @@ def read_vcf(vcf_file):
             vcf_dict[key].append(convert_string(line[idx]))
         # get mutation type
         if len(line[3]) == len(line[4]):
-            vcf_dict["TYPE"].append("SNV")
+            vcf_dict["MUT_TYPE_"].append("SNV")
         elif len(line[3]) < len(line[4]):
-            vcf_dict["TYPE"].append("INS")
+            vcf_dict["MUT_TYPE_"].append("INS")
         elif len(line[3]) > len(line[4]):
-            vcf_dict["TYPE"].append("DEL")
+            vcf_dict["MUT_TYPE_"].append("DEL")
         visited_keys.extend(header[0:6])
-        visited_keys.append("TYPE")
+        visited_keys.append("MUT_TYPE_")
         # get data from info field
         for info in line[7].split(";"):
             if "=" in info:
@@ -117,7 +117,7 @@ def extract_vcf_data(vcf_files, threshold=0):
             if not vcf_dict["AF"][idx] >= threshold:
                 continue
             frequency_list.append(
-                (f"{vcf_dict['POS'][idx]}_{vcf_dict['REF'][idx]}_{vcf_dict['ALT'][idx]}_{vcf_dict['TYPE'][idx]}", vcf_dict['AF'][idx])
+                (f"{vcf_dict['POS'][idx]}_{vcf_dict['REF'][idx]}_{vcf_dict['ALT'][idx]}_{vcf_dict['MUT_TYPE_'][idx]}", vcf_dict['AF'][idx])
             )
         frequency_lists.append(frequency_list)
     # sort by mutation index
@@ -179,13 +179,15 @@ def delete_common_mutations(frequency_array, unique_mutations):
     mut_to_del = []
 
     for idx in range(0, len(frequency_array[0])):
+        check_all = []
         for frequency_list in frequency_array:
-            if frequency_list[idx] != 0:
-                common_mut = True
-            else:
-                common_mut = False
-                break
-        if common_mut:
+            check_all.append(frequency_list[idx])
+        # check if all mutation in a column are zero (happens with some weird callers)
+        if all(x == 0 for x in check_all):
+            mut_to_del.append(idx)
+        # check if frequencies are present in all columns and the maximal diff is greater than 0.5
+        # example [0.8, 0.7, 0.3] is not deleted whereas [0.8, 0.7, 0.7] is deleted
+        elif all(x > 0 for x in check_all) and max(check_all)-min(check_all) < 0.5:
             mut_to_del.append(idx)
 
     for idx in sorted(mut_to_del, reverse=True):
@@ -272,7 +274,8 @@ def create_track_dict(unique_mutations, gff3_info, annotation_type):
                          gff3_info[type][annotation]["stop"])
                     )
     if not genes_with_mutations:
-        sys.exit("none of the given annotation types were found in gff3.")
+        print("\033[31m\033[1mWARNING:\033[0m either the annotation types were not found in gff3 or the mutations are not within genes.")
+        return {}, 0
 
     # create a dict and sort
     gene_dict = {element[0]: [element[1:4]] for element in genes_with_mutations}