diff --git a/public/java/src/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegions.java b/public/java/src/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegions.java
index 01bfe396a..384affcb7 100644
--- a/public/java/src/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegions.java
+++ b/public/java/src/org/broadinstitute/sting/gatk/traversals/TraverseActiveRegions.java
@@ -147,13 +147,13 @@ public class TraverseActiveRegions <M,T> extends TraversalEngine<M,T,ActiveRegio
                 ActiveRegion bestRegion = activeRegion;
                 for( final ActiveRegion otherRegionToTest : workQueue ) {
                     if( otherRegionToTest.getLocation().sizeOfOverlap(readLoc) >= maxOverlap ) {
-                        maxOverlap = otherRegionToTest.getLocation().sizeOfOverlap(readLoc);
+                        maxOverlap = otherRegionToTest.getLocation().sizeOfOverlap( readLoc );
                         bestRegion = otherRegionToTest;
                     }
                 }
                 bestRegion.add( (GATKSAMRecord) read, true );
 
-                // The read is also added to all other region in which it overlaps but marked as non-primary
+                // The read is also added to all other regions in which it overlaps but marked as non-primary
                 if( !bestRegion.equals(activeRegion) ) {
                     activeRegion.add( (GATKSAMRecord) read, false );
                 }
diff --git a/public/java/src/org/broadinstitute/sting/gatk/walkers/annotator/TransmissionDisequilibriumTest.java b/public/java/src/org/broadinstitute/sting/gatk/walkers/annotator/TransmissionDisequilibriumTest.java
index ecdde1e4f..43d5f0b28 100644
--- a/public/java/src/org/broadinstitute/sting/gatk/walkers/annotator/TransmissionDisequilibriumTest.java
+++ b/public/java/src/org/broadinstitute/sting/gatk/walkers/annotator/TransmissionDisequilibriumTest.java
@@ -8,7 +8,6 @@ import org.broadinstitute.sting.gatk.walkers.annotator.interfaces.AnnotatorCompa
 import org.broadinstitute.sting.gatk.walkers.annotator.interfaces.ExperimentalAnnotation;
 import org.broadinstitute.sting.gatk.walkers.annotator.interfaces.InfoFieldAnnotation;
 import org.broadinstitute.sting.utils.MathUtils;
-import org.broadinstitute.sting.utils.MendelianViolation;
 import org.broadinstitute.sting.utils.codecs.vcf.VCFHeaderLineType;
 import org.broadinstitute.sting.utils.codecs.vcf.VCFInfoHeaderLine;
 import org.broadinstitute.sting.utils.exceptions.UserException;
@@ -18,7 +17,7 @@ import java.util.*;
 
 /**
  * Created by IntelliJ IDEA.
- * User: rpoplin
+ * User: rpoplin, lfran
  * Date: 11/14/11
  */
 
@@ -28,6 +27,7 @@ public class TransmissionDisequilibriumTest extends InfoFieldAnnotation implemen
     private final static int REF = 0;
     private final static int HET = 1;
     private final static int HOM = 2;
+    private final static int MIN_NUM_VALID_TRIOS = 5; // don't calculate this population-level statistic if there are less than X trios with full genotype likelihood information
 
     public Map<String, Object> annotate(RefMetaDataTracker tracker, AnnotatorCompatibleWalker walker, ReferenceContext ref, Map<String, AlignmentContext> stratifiedContexts, VariantContext vc) {
         if ( trios == null ) {
@@ -50,7 +50,9 @@ public class TransmissionDisequilibriumTest extends InfoFieldAnnotation implemen
             }
         }
 
-        toRet.put("TDT", calculateTDT( vc, triosToTest ));
+        if( triosToTest.size() >= MIN_NUM_VALID_TRIOS ) {
+            toRet.put("TDT", calculateTDT( vc, triosToTest ));
+        }
 
         return toRet;
     }