diff --git a/drexml/datasets.py b/drexml/datasets.py
index 23340ee7..e8db1c18 100644
--- a/drexml/datasets.py
+++ b/drexml/datasets.py
@@ -29,7 +29,7 @@
 RECORD_ID = "7737166"
 
 
-def fetch_file(disease, key, version="latest", debug=False):
+def fetch_file(disease, key, env, version="latest", debug=False):
     """Retrieve data."""
     print(f"Retrieving {key}")
     experiment_env_path = pathlib.Path(disease)
@@ -52,7 +52,10 @@ def fetch_file(disease, key, version="latest", debug=False):
             data_path = experiment_env_path.parent
         path = data_path.joinpath(env[key])
 
-    return load_df(path, key)
+    frame = load_df(path, key)
+    frame = preprocess_frame(frame, env, key)
+
+    return frame
 
 
 def load_df(path, key=None):
@@ -76,8 +79,6 @@ def load_df(path, key=None):
     try:
         # tsv, and compressed tsv
         res = pd.read_csv(path, sep="\t")
-        if "index" in res.columns:
-            res = res.set_index("index", drop=True)
     except (ParserError, KeyError, UnicodeDecodeError) as err:
         print("Error found while trying to load a TSV or compressed TSV.")
         print(err)
@@ -94,14 +95,6 @@ def load_df(path, key=None):
     if res.shape[0] == 0:
         raise NotImplementedError("Format not implemented yet.")
 
-    if key is not None:
-        index_name_options = get_index_name_options(key)
-
-        for name in index_name_options:
-            if name in res.columns:
-                res = res.set_index(name, drop=True)
-        res.index = res.index.astype(str)
-
     return res
 
 
@@ -115,6 +108,49 @@ def get_index_name_options(key):
         return ["index"]
 
 
+def preprocess_frame(res, env, key):
+
+    if key is not None:
+        index_name_options = get_index_name_options(key)
+
+    for name in index_name_options:
+        if name in res.columns:
+            res = res.set_index(name, drop=True)
+    res.index = res.index.astype(str)
+
+    if key == "gene_exp":
+        return preprocess_gexp(res)
+    elif key == "pathvals":
+        return preprocess_activities(res)
+    elif key == "circuits":
+        return preprocess_map(res, env["circuits_column"])
+    elif key == "genes":
+        return preprocess_genes(res, env["genes_column"])
+
+
+def preprocess_gexp(frame):
+    frame.columns = frame.columns.str.replace("X", "")
+    return frame
+
+
+def preprocess_activities(frame):
+    frame.columns = frame.columns.str.replace("-", ".").str.replace(" ", ".")
+    return frame
+
+
+def preprocess_map(frame, circuits_column):
+    frame.index = frame.index.str.replace("-", ".").str.replace(" ", ".")
+    frame[circuits_column] = frame[circuits_column].astype(bool)
+
+    return frame
+
+
+def preprocess_genes(frame, genes_column):
+    frame = frame.loc[frame[genes_column]]
+
+    return frame
+
+
 def get_disease_data(disease, debug):
     """Get data for a disease.
 
@@ -141,24 +177,25 @@ def get_disease_data(disease, debug):
     genes_column = env["genes_column"]
     circuits_column = env["circuits_column"]
 
-    gene_exp = fetch_file(disease, key="gene_exp", version="latest", debug=debug)
-    gene_exp.columns = gene_exp.columns.str.replace("X", "")
-
-    pathvals = fetch_file(disease, key="pathvals", version="latest", debug=debug)
-    pathvals.columns = pathvals.columns.str.replace("-", ".").str.replace(" ", ".")
-    circuits = fetch_file(disease, key="circuits", version="latest", debug=debug)
-    circuits.index = circuits.index.str.replace("-", ".").str.replace(" ", ".")
-    circuits[circuits_column] = circuits[circuits_column].astype(bool)
-    genes = fetch_file(disease, key="genes", version="latest", debug=debug)
+    gene_exp = fetch_file(
+        disease, key="gene_exp", env=env, version="latest", debug=debug
+    )
+    pathvals = fetch_file(
+        disease, key="pathvals", env=env, version="latest", debug=debug
+    )
+    circuits = fetch_file(
+        disease, key="circuits", env=env, version="latest", debug=debug
+    )
+    genes = fetch_file(disease, key="genes", env=env, version="latest", debug=debug)
 
     # gene_exp = gene_exp[genes.index[genes[genes_column]]]
 
-    getx_entrez = gene_exp.columns
-    this_genes = genes.index[genes[genes_column]]
-    if this_genes.difference(getx_entrez).size > 0:
-        print(f"# genes not present in GTEx: {this_genes.difference(getx_entrez).size}")
+    gtex_entrez = gene_exp.columns
+    gene_diff = genes.index.difference(gtex_entrez).size
+    if gene_diff > 0:
+        print(f"# genes not present in GTEx: {gene_diff}")
 
-    usable_genes = this_genes.intersection(getx_entrez)
+    usable_genes = genes.index.intersection(gtex_entrez)
 
     gene_exp = gene_exp[usable_genes]
     pathvals = pathvals[circuits.index[circuits[circuits_column]]]