diff --git a/mutalyzer/variantchecker.py b/mutalyzer/variantchecker.py
index d0b5faef876f092917078832a62b63d6baa038c0..7b5dc5ed54b1c8e94e4c6b4236f0f04403e8c8fe 100644
--- a/mutalyzer/variantchecker.py
+++ b/mutalyzer/variantchecker.py
@@ -1223,7 +1223,7 @@ def _add_transcript_info(mutator, transcript, output):
     """
     # Add transcript info to output.
     if transcript.transcribe:
-        output.addOutput('myTranscriptDescription', transcript.description)
+        output.addOutput('myTranscriptDescription', transcript.description or '=')
         output.addOutput('origMRNA',
             str(util.splice(mutator.orig, transcript.mRNA.positionList)))
         output.addOutput('mutatedMRNA',
@@ -1661,7 +1661,7 @@ def check_variant(description, output):
     if ';' in record.record.description:
         generated_description = '[' + record.record.description + ']'
     else:
-        generated_description = record.record.description
+        generated_description = record.record.description or '='
 
     output.addOutput('genomicDescription', '%s:%c.%s' % \
                      (reference, record.record.molType, generated_description))
@@ -1673,7 +1673,7 @@ def check_variant(description, output):
         if ';' in record.record.chromDescription:
             chromosomal_description = '[' + record.record.chromDescription + ']'
         else:
-            chromosomal_description = record.record.chromDescription
+            chromosomal_description = record.record.chromDescription or '='
         output.addOutput('genomicChromDescription', '%s:%c.%s' % \
                          (record.record.recordId,
                           record.record.molType, chromosomal_description))
@@ -1694,7 +1694,7 @@ def check_variant(description, output):
             if ';' in transcript.description:
                 generated_description = '[' + transcript.description + ']'
             else:
-                generated_description = transcript.description
+                generated_description = transcript.description or '='
 
             if record.record._sourcetype == 'LRG':
                 if transcript.name:
diff --git a/tests/test_variantchecker.py b/tests/test_variantchecker.py
index 65d5c45cdd71784a0688ae390832e960fcdc98de..f5ae5034f58b5103f4dcf7c61bfb15484912771f 100644
--- a/tests/test_variantchecker.py
+++ b/tests/test_variantchecker.py
@@ -6,6 +6,7 @@ Tests for the variantchecker module.
 #import logging; logging.basicConfig()
 from nose.tools import *
 
+from mutalyzer.util import skip
 from mutalyzer.output import Output
 from mutalyzer.variantchecker import check_variant
 
@@ -496,3 +497,33 @@ class TestVariantchecker():
                      '31317229:n.105del')
         assert '31317229(FCER1A_v001):c.6del' \
                in self.output.getOutput('descriptions')
+
+    def test_nop_nm(self):
+        """
+        Variant on NM without effect should be described as '='.
+        """
+        check_variant('NM_002001.2:c.1_3delinsATG', self.output)
+        error_count, _, _ = self.output.Summary()
+        assert_equal(error_count, 0)
+        assert_equal(self.output.getIndexedOutput('genomicDescription', 0),
+                     'NM_002001.2:n.=')
+        assert 'NM_002001.2(FCER1A_v001):c.=' \
+               in self.output.getOutput('descriptions')
+
+    @skip
+    def test_nop_ud(self):
+        """
+        Variant on UD without effect should be described as '='.
+
+        Todo: We cannot use UD references in unit tests, unless we implement
+            a way to create them inside the unit test.
+        """
+        check_variant('UD_127955523176:g.5T>T', self.output)
+        error_count, _, _ = self.output.Summary()
+        assert_equal(error_count, 0)
+        assert_equal(self.output.getIndexedOutput('genomicChromDescription', 0),
+                     'NC_000023.10:g.=')
+        assert_equal(self.output.getIndexedOutput('genomicDescription', 0),
+                     'UD_127955523176:g.=')
+        assert 'UD_127955523176(DMD_v001):c.=' \
+               in self.output.getOutput('descriptions')
diff --git a/tests/test_webservice.py b/tests/test_webservice.py
index 7d179e6fc403805603c0cf773661de80300cab0c..f50ecc3e3597969755d9d69fd77982fdd8006e0a 100644
--- a/tests/test_webservice.py
+++ b/tests/test_webservice.py
@@ -8,6 +8,7 @@ from mutalyzer.util import monkey_patch_suds; monkey_patch_suds()
 import os
 from datetime import datetime, timedelta
 import mutalyzer
+from mutalyzer.util import skip
 from mutalyzer.output import Output
 from mutalyzer.sync import CacheSync
 from mutalyzer import Db
@@ -334,9 +335,13 @@ class TestWebservice():
         assert_equal(r.sourceGi, '222352156')
         assert_equal(r.molecule, 'n')
 
+    @skip
     def test_runmutalyzer_reference_info_ud(self):
         """
         Get reference info for a UD variant.
+
+        Todo: We cannot use UD references in unit tests, unless we implement
+           a way to create them inside the unit test.
         """
         r = self.client.service.runMutalyzer('UD_129433404385:g.1del')
         assert_equal(r.errors, 0)