separate alt het variants out

src/vcf_qc.py

@@ -102,17 +102,21 @@ def get_het_hom_counts(vcf) -> dict:
 
     sample = samples[0]
 
-    counts = {"het": [], "hom": [], "x_het": [], "x_hom": []}
+    counts = {"het": [], "hom": [], "alt_het": [], "x_het": [], "x_hom": []}
 
     variant_count = autosome_count = x_variant_count = 0
 
+    gts = []
+
     for record in vcf_handle.fetch():
         sample_fields = record.samples[sample]
 
         printable_var = (
             f"{record.chrom}-{record.pos}-{record.ref}-{','.join(record.alts)}"
         )
 
+        gts.append(sample_fields["GT"])
+
         missing_fields = [
             x for x in ["AD", "DP", "GT"] if not x in sample_fields
         ]
@@ -136,7 +140,7 @@ def get_het_hom_counts(vcf) -> dict:
 
         non_ref_aaf = non_ref_depth / informative_total_depth
 
-        if len(set(sample_fields["GT"])) == 1:
+        if sample_fields["GT"] == (1, 1):
             # homozygous variant
             if is_autosome(record.chrom):
                 autosome_count += 1
@@ -145,15 +149,19 @@ def get_het_hom_counts(vcf) -> dict:
             if re.match(r"(chr)?x", record.chrom, re.IGNORECASE):
                 x_variant_count += 1
                 counts["x_hom"].append(non_ref_aaf)
-        else:
-            # heterozygous variant
+        elif sample_fields["GT"] == (0, 1):
+            # standard ref alt heterozygous variant
             if is_autosome(record.chrom):
                 autosome_count += 1
                 counts["het"].append(non_ref_aaf)
 
             if re.match(r"(chr)?x", record.chrom, re.IGNORECASE):
                 x_variant_count += 1
                 counts["x_het"].append(non_ref_aaf)
+        else:
+            # heterozygous alternate variant
+            if is_autosome(record.chrom):
+                counts["alt_het"].append(non_ref_aaf)
 
         # handy print for the logs for sense checking
         print(
@@ -209,6 +217,7 @@ def calculate_ratios(counts) -> dict:
     print(
         f"\nTotal het counts: {len(counts['het'])}\n"
         f"Total hom counts: {len(counts['hom'])}\n"
+        f"Total alt het counts: {len(counts['alt_het'])}\n"
         f"Total x het counts: {len(counts['x_het'])}\n"
         f"Total x hom counts: {len(counts['x_hom'])}\n"
     )

tests/test_vcf_qc.py

@@ -143,6 +143,7 @@ def test_aaf_calculated_correctly_for_hets_and_homs(self):
         expected_values = {
             "het": [0.45454545454545453, 0.4952076677316294],
             "hom": [1.0, 1.0],
+            "alt_het": [],
             "x_het": [],
             "x_hom": [],
         }
@@ -176,6 +177,7 @@ def test_x_chrom_variants_additionally_returned_separate(self):
         expected_values = {
             "het": [0.45454545454545453, 0.4952076677316294],
             "hom": [1.0, 1.0],
+            "alt_het": [],
             "x_het": [0.6, 0.8],
             "x_hom": [1.0, 1.0],
         }
@@ -195,7 +197,13 @@ def test_reference_calls_are_skipped(self):
             os.path.join(TEST_DATA_DIR, "test_w_ref.vcf")
         )
 
-        expected_values = {"het": [], "hom": [], "x_het": [], "x_hom": []}
+        expected_values = {
+            "het": [],
+            "hom": [],
+            "alt_het": [],
+            "x_het": [],
+            "x_hom": [],
+        }
 
         self.assertEqual(calculated_values, expected_values)
 
@@ -221,6 +229,7 @@ def test_het_and_hom_ratios_calculated_correctly(self):
         counts = {
             "het": [0.5, 0.45, 0.55],
             "hom": [1.0, 1.0, 1.0, 1.0, 0.95],
+            "alt_het": [],
             "x_het": [],
             "x_hom": [],
         }
@@ -240,6 +249,7 @@ def test_x_het_hom_calculated_correctly(self):
         counts = {
             "het": [0.5, 0.45, 0.55],
             "hom": [1.0, 1.0, 1.0, 1.0, 0.95],
+            "alt_het": [],
             "x_het": [0.45, 0.55],
             "x_hom": [1.0, 0.98],
         }