Change for issue #502 - downgrade PM2 - PM2_Supporting for variants l…

…acking frequency information.

Update Acgs2020Classifier and Acmg2015Classifier to allow for PVS1 and PM2_Supporting are sufficient to trigger LIKELY_PATHOGENIC
Change for issue #514 update AcmgEvidence to fit a Bayesian points-based system
Add new Acmg2020PointsBasedClassifier to classify AcmgEvidence based on points

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/PvalueGeneScorer.java

@@ -44,7 +44,7 @@ public PvalueGeneScorer(String probandId, Pedigree.Individual.Sex probandSex, In
         this.genePriorityScoreCalculator = new GenePriorityScoreCalculator();
         this.pValueCalculator = Objects.requireNonNull(pValueCalculator);
         AcmgEvidenceAssigner acmgEvidenceAssigner = new Acmg2015EvidenceAssigner(probandId, inheritanceModeAnnotator.getPedigree());
-        AcmgEvidenceClassifier acmgEvidenceClassifier = new Acgs2020Classifier();
+        AcmgEvidenceClassifier acmgEvidenceClassifier = new Acmg2020PointsBasedClassifier();
         this.acmgAssignmentCalculator = new AcmgAssignmentCalculator(acmgEvidenceAssigner, acmgEvidenceClassifier);
     }
 
@@ -101,6 +101,15 @@ private GeneScore calculateGeneScore(Gene gene, ModeOfInheritance modeOfInherita
 
         GenePriorityScoreCalculator.GenePriorityScore priorityScore = genePriorityScoreCalculator.calculateGenePriorityScore(gene, modeOfInheritance);
 
+        List<ModelPhenotypeMatch<Disease>> compatibleDiseaseMatches = priorityScore.getCompatibleDiseaseMatches();
+
+        List<AcmgAssignment> acmgAssignments = acmgAssignmentCalculator.calculateAcmgAssignments(modeOfInheritance, gene, contributingVariants, compatibleDiseaseMatches);
+
+//        double variantScore = acmgAssignments.stream()
+//                .mapToDouble(acmgAssignment -> acmgAssignment.acmgEvidence().postProbPath())
+//                .average()
+//                .orElse(0.1); // 0.1 is the equivalent of a 0-point VUS
+
         double variantScore = contributingVariants.stream()
                 .mapToDouble(VariantEvaluation::getVariantScore)
                 .average()
@@ -110,10 +119,6 @@ private GeneScore calculateGeneScore(Gene gene, ModeOfInheritance modeOfInherita
 
         double pValue = pValueCalculator.calculatePvalueFromCombinedScore(combinedScore);
 
-        List<ModelPhenotypeMatch<Disease>> compatibleDiseaseMatches = priorityScore.getCompatibleDiseaseMatches();
-
-        List<AcmgAssignment> acmgAssignments = acmgAssignmentCalculator.calculateAcmgAssignments(modeOfInheritance, gene, contributingVariants, compatibleDiseaseMatches);
-
         return GeneScore.builder()
                 .geneIdentifier(gene.getGeneIdentifier())
                 .modeOfInheritance(modeOfInheritance)

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/RawScoreGeneScorer.java

@@ -70,7 +70,7 @@ public RawScoreGeneScorer(String probandId, Sex probandSex, InheritanceModeAnnot
         this.contributingAlleleCalculator = new ContributingAlleleCalculator(probandId, probandSex, inheritanceModeAnnotator);
         this.genePriorityScoreCalculator = new GenePriorityScoreCalculator();
         AcmgEvidenceAssigner acmgEvidenceAssigner = new Acmg2015EvidenceAssigner(probandId, inheritanceModeAnnotator.getPedigree());
-        AcmgEvidenceClassifier acmgEvidenceClassifier = new Acgs2020Classifier();
+        AcmgEvidenceClassifier acmgEvidenceClassifier = new Acmg2020PointsBasedClassifier();
         this.acmgAssignmentCalculator = new AcmgAssignmentCalculator(acmgEvidenceAssigner, acmgEvidenceClassifier);
     }
 

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acgs2020Classifier.java

@@ -78,6 +78,9 @@ private static boolean isPathogenic(int pvs, int ps, int pm, int pp) {
     }
 
     private static boolean isLikelyPathogenic(int pvs, int ps, int pm, int pp) {
+        if (pvs == 1 && pp == 1) {
+            return true;
+        }
         if (ps >= 2) {
             return true;
         }

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acmg2015Classifier.java

@@ -78,7 +78,7 @@ private static boolean isPathogenic(int pvs, int ps, int pm, int pp) {
     }
 
     private static boolean isLikelyPathogenic(int pvs, int ps, int pm, int pp) {
-        if (pvs == 1 && pm == 1) {
+        if (pvs == 1 && (pm == 1 || pp == 1)) {
             return true;
         }
         if (ps == 1 && (pm == 1 || pm == 2) || ps == 1 && pp >= 2) {

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acmg2015EvidenceAssigner.java

@@ -80,12 +80,18 @@ public Acmg2015EvidenceAssigner(String probandId, Pedigree pedigree) {
      */
     // https://www.ncbi.nlm.nih.gov/clinvar/variation/464/ - check in ClinVar VCF if there is MOI information for a classification
     public AcmgEvidence assignVariantAcmgEvidence(VariantEvaluation variantEvaluation, ModeOfInheritance modeOfInheritance, List<VariantEvaluation> contributingVariants, List<Disease> knownDiseases, List<ModelPhenotypeMatch<Disease>> compatibleDiseaseMatches) {
-        // try strict ACMG assignments only if there are known disease-gene associations
-        if (knownDiseases.isEmpty()) {
-            return AcmgEvidence.empty();
+        AcmgEvidence.Builder acmgEvidenceBuilder = AcmgEvidence.builder();
+
+        FrequencyData frequencyData = variantEvaluation.getFrequencyData();
+        // BA1 "Allele frequency is >5% in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium"
+        if (frequencyData.getMaxFreq() >= 5.0) {
+            acmgEvidenceBuilder.add(BA1);
+            // BA1 is supposed to be used as a filtering criterion where no other evidence need be considered.
+            return acmgEvidenceBuilder.build();
         }
+        // PM2 "Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium"
+        assignPM2(acmgEvidenceBuilder, frequencyData);
 
-        AcmgEvidence.Builder acmgEvidenceBuilder = AcmgEvidence.builder();
 
         boolean hasCompatibleDiseaseMatches = !compatibleDiseaseMatches.isEmpty();
 
@@ -106,12 +112,6 @@ public AcmgEvidence assignVariantAcmgEvidence(VariantEvaluation variantEvaluatio
             assignBS4(acmgEvidenceBuilder, variantEvaluation, proband);
         }
 
-        FrequencyData frequencyData = variantEvaluation.getFrequencyData();
-        // PM2 "Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium"
-        assignPM2(acmgEvidenceBuilder, frequencyData);
-        // BA1 "Allele frequency is >5% in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium"
-        assignBA1(acmgEvidenceBuilder, frequencyData);
-
         // PM3 "For recessive disorders, detected in trans with a pathogenic variant"
         assignPM3orBP2(acmgEvidenceBuilder, variantEvaluation, modeOfInheritance, contributingVariants, hasCompatibleDiseaseMatches);
         // PM4 Protein length changes as a result of in-frame deletions/insertions in a nonrepeat region or stop-loss variants
@@ -395,14 +395,15 @@ private boolean possibleDeNovo(SampleGenotype ancestorGenotype, SampleGenotype p
     private void assignPM1(Map<AcmgCriterion, Evidence> acmgEvidenceBuilder) {
         // TODO - need UniProt domain / site info and clinvar counts
         //  can upgrade to STRONG
+        // https://www.cell.com/ajhg/fulltext/S0002-9297(22)00461-X suggests to limit the combined evidence from PM1 and PP3 to strong
     }
 
     /**
      * PM2 "Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium"
      */
     private void assignPM2(AcmgEvidence.Builder acmgEvidenceBuilder, FrequencyData frequencyData) {
         if (!frequencyData.hasEspData() && !frequencyData.hasExacData() && !frequencyData.hasDbSnpData()) {
-            acmgEvidenceBuilder.add(PM2);
+            acmgEvidenceBuilder.add(PM2, Evidence.SUPPORTING);
         }
         // TODO: require disease incidence in carriers and penetrance to be able to calculate expected frequencies for AR
     }
@@ -553,15 +554,6 @@ private void assignPP4(AcmgEvidence.Builder acmgEvidenceBuilder, List<ModelPheno
         }
     }
 
-    /**
-     * BA1 "Allele frequency is >5% in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium"
-     */
-    private void assignBA1(AcmgEvidence.Builder acmgEvidenceBuilder, FrequencyData frequencyData) {
-        if (frequencyData.getMaxFreq() >= 5.0) {
-            acmgEvidenceBuilder.add(BA1);
-        }
-    }
-
     /**
      * BS4 "Lack of segregation in affected members of a family"
      */

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acmg2020PointsBasedClassifier.java

@@ -0,0 +1,58 @@
+package org.monarchinitiative.exomiser.core.analysis.util.acmg;
+
+/**
+ * This is recommended by the ClinGen <a href = "https://clinicalgenome.org/working-groups/sequence-variant-interpretation/">Sequence Variant Interpretation (SVI)</a> group
+ * <p>
+ * Fitting a naturally scaled point system to the ACMG/AMP variant classification guidelines - Tavtigian et al. 2020,
+ * (DOI:10.1002/humu.24088).
+ * </p>
+ */
+public class Acmg2020PointsBasedClassifier implements AcmgEvidenceClassifier {
+
+    @Override
+    public AcmgClassification classify(AcmgEvidence acmgEvidence) {
+
+        if (acmgEvidence.ba() == 1) {
+            return AcmgClassification.BENIGN;
+        }
+
+        return classification(acmgEvidence.points());
+    }
+
+    protected AcmgClassification classification(double points) {
+        if (points >= 10) {
+            return AcmgClassification.PATHOGENIC;
+        }
+        if (points >= 6 && points <= 9) {
+            return AcmgClassification.LIKELY_PATHOGENIC;
+        }
+        if (points >= 0 && points <= 5) {
+            return AcmgClassification.UNCERTAIN_SIGNIFICANCE;
+        }
+        if (points >= -6 && points <= -1) {
+            return AcmgClassification.LIKELY_BENIGN;
+        }
+        // points <= -7
+        return AcmgClassification.BENIGN;
+    }
+
+    public double score(AcmgEvidence acmgEvidence) {
+        if (acmgEvidence.ba() == 1) {
+            return 0;
+        }
+        int maxPath = Math.min(scorePaths(acmgEvidence), 10);
+        int minBenign = Math.max(scoreBenign(acmgEvidence), -4);
+
+        double score = ((maxPath - minBenign) - -4) / (double) (10 - -4);
+        return Math.max(Math.min(score, 1.0), 0.0);
+    }
+
+    private int scorePaths(AcmgEvidence acmgEvidence) {
+        return acmgEvidence.pp() + (acmgEvidence.pm() * 2) + (acmgEvidence.ps() * 4) + (acmgEvidence.pvs() * 8);
+    }
+
+    private int scoreBenign(AcmgEvidence acmgEvidence) {
+        return acmgEvidence.bp() + (acmgEvidence.bs() * 4);
+    }
+
+}

exomiser-core/src/main/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/AcmgEvidence.java

@@ -32,6 +32,21 @@
  */
 public class AcmgEvidence {
 
+    // These constants are derived in "Modeling the ACMG/AMP Variant Classification Guidelines as a Bayesian
+    //  Classification Framework" Tavtigian et al. 2018, DOI:10.1038/gim.2017.210
+    // https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336098/bin/NIHMS915467-supplement-Supplemental_Table_S1.xlsx
+
+    // Very_Strong == (2 * Strong) == (2 * Moderate) == (2 * Supporting)
+    // therefore points Supporting = 1, Moderate = 2, Strong = 4, Very_strong = 8 can be assigned and these fit to a
+    // Bayesian classification framework where (using the combining rules from Riggs et al. 2016) the posterior
+    // probabilities are Path >= 0.99, LikelyPath 0.90 - 0.98, LikelyBenign 0.1 - 0.01, Benign < 0.01
+
+    private static final double PRIOR_PROB = 0.1;
+    private static final double ODDS_PATH_VERY_STRONG = 350.0;
+    private static final double EXPONENTIAL_PROGRESSION = 2.0;
+    private static final double SUPPORTING_EVIDENCE_EXPONENT = Math.pow(EXPONENTIAL_PROGRESSION, -3); // 0.125
+    private static final double ODDS_PATH_SUPPORTING = Math.pow(ODDS_PATH_VERY_STRONG, SUPPORTING_EVIDENCE_EXPONENT); // 2.08
+
     private static final AcmgEvidence EMPTY = new AcmgEvidence(Map.of());
 
     @JsonProperty
@@ -43,12 +58,17 @@ public class AcmgEvidence {
     private int pp = 0;
 
     private int ba = 0;
+    private int bvs = 0;
     private int bs = 0;
+    private int bm = 0;
     private int bp = 0;
 
+    private int points = 0;
+
     private AcmgEvidence(Map<AcmgCriterion, Evidence> evidence) {
         this.evidence = evidence == null || evidence.isEmpty() ? Map.of() : Collections.unmodifiableMap(new EnumMap<>(evidence));
         countCriteriaEvidence(this.evidence);
+        points = pathPoints() - benignPoints();
     }
 
     @JsonCreator
@@ -89,9 +109,15 @@ private void countCriteriaEvidence(Map<AcmgCriterion, Evidence> evidence) {
                     case STAND_ALONE:
                         ba++;
                         break;
+                    case VERY_STRONG:
+                        bvs++;
+                        break;
                     case STRONG:
                         bs++;
                         break;
+                    case MODERATE:
+                        bm++;
+                        break;
                     case SUPPORTING:
                         bp++;
                         break;
@@ -103,6 +129,21 @@ private void countCriteriaEvidence(Map<AcmgCriterion, Evidence> evidence) {
         }
     }
 
+    public int pathPoints() {
+        return (int) (pp + pm * 2.0 + ps * 4.0 + pvs * 8.0);
+    }
+
+    public int benignPoints() {
+        // n.b. here BA1 is given the equivalent weight as PVS1. This was *not* specified in the two papers. Specifically,
+        // in the 2018 paper they state "We excluded BA1, “benign stand alone” because it is used as absolute evidence
+        // that a variant is benign, irrespective of other evidence, which is contrary to Bayesian reasoning. The BA1
+        // filter is useful for excluding a variant from entering a Bayesian framework, and will be addressed separately
+        // by the ClinGen Sequence Variant Interpretation (SVI) Working Group."
+        // Similarly, BM and BVS have been added here because it is possible to assign a Moderate, Strong or VeryStrong
+        // modifier to BP4 which will result in a VUS rather than LB if not included
+        return (int) (bp + bm * 2.0 + bs * 4.0 + bvs * 8.0 + ba * 8.0);
+    }
+
     public boolean hasCriterion(AcmgCriterion acmgCriterion) {
         return evidence.containsKey(acmgCriterion);
     }
@@ -144,14 +185,34 @@ public int ba() {
         return ba;
     }
 
+    public int bvs() {
+        return bvs;
+    }
+
     public int bs() {
         return bs;
     }
 
+    public int bm() {
+        return bm;
+    }
+
     public int bp() {
         return bp;
     }
 
+    public int points() {
+        return points;
+    }
+
+    public double postProbPath() {
+        // Equation 2 from Tavtigian et al., 2020 (DOI: 10.1002/humu.24088) which is a re-written from of equation 5 from
+        // Tavtigian et al., 2018 (DOI: 10.1038/gim.2017.210)
+        double oddsPath = Math.pow(ODDS_PATH_SUPPORTING, points);
+        // posteriorProbability = (OddsPathogenicity*Prior P)/((OddsPathogenicity−1)*Prior_P+1)
+        return (oddsPath * PRIOR_PROB) / ((oddsPath - 1) * PRIOR_PROB + 1);
+    }
+
     public static AcmgEvidence.Builder builder() {
         return new Builder();
     }

exomiser-core/src/test/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acgs2020ClassifierTest.java

@@ -91,6 +91,7 @@ void classifiesPathogenic(String criteria) {
     @CsvSource({
 //      (c)  >=2 Strong
             "PS1 PS2",
+            "PVS1 PP1", // updated rule https://clinicalgenome.org/site/assets/files/5182/pm2_-_svi_recommendation_-_approved_sept2020.pdf
 //      (b)  1 Strong (PS1–PS4) AND
 //             1–2 moderate (PM1–PM6) OR
             "PS1 PM1 PM2",
@@ -143,7 +144,7 @@ void classifiesLikelyBenign(String criteria) {
     @ParameterizedTest
     @CsvSource({
 //            (i)  Other criteria shown above are not met
-            "PVS1 PP1",
+//            "PVS1 PP1", //
             "PS1 PP1", // VUS_Hot
             "PM1 PM2 PP1", // VUS_Hot
 //            "PM1 PP1 PP2 PP3", // VUS_Hot - classified as LP

exomiser-core/src/test/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acmg2015ClassifierTest.java

@@ -71,6 +71,7 @@ void classifiesPathogenic(String criteria) {
     @CsvSource({
 //            (i)   1 Very strong (PVS1) AND 1 moderate (PM1–PM6)
             "PVS1 PM1",
+            "PVS1 PP1", // updated rule https://clinicalgenome.org/site/assets/files/5182/pm2_-_svi_recommendation_-_approved_sept2020.pdf
 //            OR (ii)   1 Strong (PS1–PS4) AND 1–2 moderate (PM1–PM6)
             "PS1 PM1 PM2",
 //            OR (iii)   1 Strong (PS1–PS4) AND ≥2 supporting (PP1–PP5)
@@ -121,7 +122,7 @@ void classifiesLikelyBenign(String criteria) {
     @ParameterizedTest
     @CsvSource({
 //            (i)  Other criteria shown above are not met
-            "PVS1 PP1",
+//            "PVS1 PP1", - Changed to LP in https://clinicalgenome.org/site/assets/files/5182/pm2_-_svi_recommendation_-_approved_sept2020.pdf
             "PS1 PP1", // VUS_Hot
             "PM1 PM2 PP1", // VUS_Hot
 //            "PM1 PP1 PP2 PP3", // VUS_Hot - classified as LP

exomiser-core/src/test/java/org/monarchinitiative/exomiser/core/analysis/util/acmg/Acmg2015EvidenceAssignerTest.java

@@ -194,11 +194,11 @@ void testAssignsPM2() {
 
         AcmgEvidence acmgEvidence = instance.assignVariantAcmgEvidence(variantEvaluation, ModeOfInheritance.AUTOSOMAL_DOMINANT, List.of(variantEvaluation), List.of(cowdenSyndrome), List.of());
 
-        assertThat(acmgEvidence, equalTo(AcmgEvidence.builder().add(AcmgCriterion.PM2).build()));
+        assertThat(acmgEvidence, equalTo(AcmgEvidence.builder().add(AcmgCriterion.PM2, Evidence.SUPPORTING).build()));
     }
 
     @Test
-    void testVariantMustBeInGeneWithKnownDiseaseAssociationForAcmgCriteriaToBeAssigned() {
+    void testVariantNeedNotBeInGeneWithKnownDiseaseAssociationForAcmgCriteriaToBeAssigned() {
         Acmg2015EvidenceAssigner instance = new Acmg2015EvidenceAssigner("proband", Pedigree.empty());
         VariantEvaluation variantEvaluation = TestFactory.variantBuilder(1, 12345, "A", "G")
                 // n.b. missing frequency data - should trigger PM2
@@ -207,7 +207,8 @@ void testVariantMustBeInGeneWithKnownDiseaseAssociationForAcmgCriteriaToBeAssign
         // Requires variant to be in gene associated with a disorder in order that any ACMG criteria can be applied
         AcmgEvidence acmgEvidence = instance.assignVariantAcmgEvidence(variantEvaluation, ModeOfInheritance.AUTOSOMAL_DOMINANT, List.of(variantEvaluation), List.of(), List.of());
 
-        assertThat(acmgEvidence, equalTo(AcmgEvidence.empty()));
+        AcmgEvidence expected = AcmgEvidence.builder().add(PM2, Evidence.SUPPORTING).build();
+        assertThat(acmgEvidence, equalTo(expected));
     }
 
     @Test