#447 - implement babelfish for VCF

src/hgvs/extras/babelfish.py

@@ -1,8 +1,15 @@
 """translate between HGVS and other formats"""
+import os
 
-import bioutils.assemblies
-
+import hgvs
 import hgvs.normalizer
+from bioutils.assemblies import make_ac_name_map, make_name_ac_map
+from bioutils.sequences import reverse_complement
+from hgvs.edit import NARefAlt
+from hgvs.location import Interval, SimplePosition
+from hgvs.normalizer import Normalizer
+from hgvs.posedit import PosEdit
+from hgvs.sequencevariant import SequenceVariant
 
 
 def _as_interbase(posedit):
@@ -18,21 +25,18 @@ def _as_interbase(posedit):
 
 class Babelfish:
     def __init__(self, hdp, assembly_name):
+        self.assembly_name = assembly_name
         self.hdp = hdp
         self.hn = hgvs.normalizer.Normalizer(hdp, cross_boundaries=False, shuffle_direction=5, validate=False)
-        self.ac_to_chr_name_map = {
-            sr["refseq_ac"]: sr["name"] for sr in bioutils.assemblies.get_assembly("GRCh38")["sequences"]
-        }
+        self.ac_to_name_map = make_ac_name_map(assembly_name)
+        self.name_to_ac_map = make_name_ac_map(assembly_name)
 
     def hgvs_to_vcf(self, var_g):
         """**EXPERIMENTAL**
 
         converts a single hgvs allele to (chr, pos, ref, alt) using
         the given assembly_name. The chr name uses official chromosome
         name (i.e., without a "chr" prefix).
-
-        Returns None for non-variation (e.g., NC_000006.12:g.49949407=)
-
         """
 
         if var_g.type != "g":
@@ -42,33 +46,63 @@ def hgvs_to_vcf(self, var_g):
 
         (start_i, end_i) = _as_interbase(vleft.posedit)
 
-        chr = self.ac_to_chr_name_map[vleft.ac]
+        chrom = self.ac_to_name_map[vleft.ac]
 
         typ = vleft.posedit.edit.type
 
         if typ == "dup":
             start_i -= 1
             alt = self.hdp.seqfetcher.fetch_seq(vleft.ac, start_i, end_i)
             ref = alt[0]
-            end_i = start_i
-            return (chr, start_i + 1, ref, alt, typ)
-
-        if vleft.posedit.edit.ref == vleft.posedit.edit.alt:
-            return None
-
-        alt = vleft.posedit.edit.alt or ""
-
-        if end_i - start_i == 1 and vleft.posedit.length_change == 0:
-            # SNVs aren't left anchored
+        elif typ == 'inv':
             ref = vleft.posedit.edit.ref
-
+            alt = reverse_complement(ref)
         else:
-            # everything else is left-anchored
-            start_i -= 1
-            ref = self.hdp.seqfetcher.fetch_seq(vleft.ac, start_i, end_i)
-            alt = ref[0] + alt
-
-        return (chr, start_i + 1, ref, alt, typ)
+            alt = vleft.posedit.edit.alt or ""
+
+            if typ in ('del', 'ins'):  # Left anchored
+                start_i -= 1
+                ref = self.hdp.seqfetcher.fetch_seq(vleft.ac, start_i, end_i)
+                alt = ref[0] + alt
+            else:
+                ref = vleft.posedit.edit.ref
+                if ref == alt:
+                    alt = '.'
+        return chrom, start_i + 1, ref, alt, typ
+
+    def vcf_to_g_hgvs(self, chrom, position, ref, alt):
+        ac = self.name_to_ac_map[chrom]
+
+        # Strip common prefix
+        if len(alt) > 1 and len(ref) > 1:
+            pfx = os.path.commonprefix([ref, alt])
+            lp = len(pfx)
+            if lp > 0:
+                ref = ref[lp:]
+                alt = alt[lp:]
+                position += lp
+
+        if ref == '':  # Insert
+            # Insert uses coordinates around the insert point.
+            start = position - 1
+            end = position
+        else:
+            start = position
+            end = position + len(ref) - 1
+
+        if alt == '.':
+            alt = ref
+
+        var_g = SequenceVariant(ac=ac,
+                                type='g',
+                                posedit=PosEdit(Interval(start=SimplePosition(start),
+                                                         end=SimplePosition(end),
+                                                         uncertain=False),
+                                                NARefAlt(ref=ref or None,
+                                                         alt=alt or None,
+                                                         uncertain=False)))
+        n = Normalizer(self.hdp)
+        return n.normalize(var_g)
 
 
 if __name__ == "__main__":

tests/test_hgvs_extras_babelfish.py

@@ -1,3 +1,43 @@
+NORM_HGVS_VCF = [
+    # Columns are: (normed-HGVS, non-normalized HGVS, VCF coordinates, non-norm VCF)
+
+    # no-op
+    ("NC_000006.12:g.49949407=", [],
+     ("6", 49949407, "A", ".", 'identity'), [("6", 49949407, "A", "A", 'identity')]),
+
+    # snv
+    ("NC_000006.12:g.49949407A>T",
+     [],
+     # was ("6", 49949406, "AA", "AT", "sub") however VT parsimony rules say it should be those below
+     ("6", 49949407, "A", "T", "sub"), []),
+    # delins
+    ("NC_000006.12:g.49949413_49949414delinsCC",
+     [],
+     # This was ("6", 49949412, "AAA", "ACC", "delins") - however VT parsimony rules say it should be those below
+     ("6", 49949413, "AA", "CC", "delins"), []),
+
+    # del, no shift
+    ("NC_000006.12:g.49949415del", [], ("6", 49949414, "AT", "A", "del"), []),
+
+    # del, w/ shift
+    ("NC_000006.12:g.49949414del", ["NC_000006.12:g.49949413del"],
+     ("6", 49949409, "GA", "G", "del"), []),
+    ("NC_000006.12:g.49949413_49949414del", [], ("6", 49949409, "GAA", "G", "del"), []),
+
+    # ins, no shift
+    ("NC_000006.12:g.49949413_49949414insC", [], ("6", 49949413, "A", "AC", "ins"), []),
+    ("NC_000006.12:g.49949414_49949415insCC", [], ("6", 49949414, "A", "ACC", "ins"), []),
+
+    # ins/dup, w/shift
+    ("NC_000006.12:g.49949414dup",
+     ["NC_000006.12:g.49949413_49949414insA", "NC_000006.12:g.49949414_49949415insA"],
+     ("6", 49949409, "G", "GA", "dup"), []),
+    ("NC_000006.12:g.49949413_49949414dup",
+     ["NC_000006.12:g.49949414_49949415insAA"],
+     ("6", 49949409, "G", "GAA", "dup"), []),
+]
+
+
 def test_hgvs_to_vcf(parser, babelfish38):
     """
       49949___  400       410       420
@@ -9,28 +49,19 @@ def test_hgvs_to_vcf(parser, babelfish38):
     def _h2v(h):
         return babelfish38.hgvs_to_vcf(parser.parse(h))
 
-    # no-op
-    assert _h2v("NC_000006.12:g.49949407=") == None
-
-    # snv
-    assert _h2v("NC_000006.12:g.49949407A>T") == ("6", 49949406, "AA", "AT", "sub")
-
-    # delins
-    assert _h2v("NC_000006.12:g.49949413_49949414delinsCC") == ("6", 49949412, "AAA", "ACC", "delins")
-
-    # del, no shift
-    assert _h2v("NC_000006.12:g.49949415del") == ("6", 49949414, "AT", "A", "del")
+    for norm_hgvs_string, alt_hgvs, expected_variant_coordinate, _ in NORM_HGVS_VCF:
+        for hgvs_string in [norm_hgvs_string] + alt_hgvs:
+            variant_coordinates = _h2v(hgvs_string)
+            assert variant_coordinates == expected_variant_coordinate
 
-    # del, w/ shift
-    assert _h2v("NC_000006.12:g.49949413del") == ("6", 49949409, "GA", "G", "del")
-    assert _h2v("NC_000006.12:g.49949414del") == ("6", 49949409, "GA", "G", "del")
-    assert _h2v("NC_000006.12:g.49949413_49949414del") == ("6", 49949409, "GAA", "G", "del")
 
-    # ins, no shift
-    assert _h2v("NC_000006.12:g.49949413_49949414insC") == ("6", 49949413, "A", "AC", "ins")
-    assert _h2v("NC_000006.12:g.49949414_49949415insCC") == ("6", 49949414, "A", "ACC", "ins")
+def test_vcf_to_hgvs(parser, babelfish38):
+    def _v2h(*v):
+        return babelfish38.vcf_to_g_hgvs(*v)
 
-    # ins/dup, w/shift
-    assert _h2v("NC_000006.12:g.49949413_49949414insA") == ("6", 49949409, "G", "GA", "dup")
-    assert _h2v("NC_000006.12:g.49949414_49949415insA") == ("6", 49949409, "G", "GA", "dup")
-    assert _h2v("NC_000006.12:g.49949414_49949415insAA") == ("6", 49949409, "G", "GAA", "dup")
+    for expected_hgvs_string, _, norm_variant_coordinate, alt_variant_coordinate in NORM_HGVS_VCF:
+        for variant_coordinate in [norm_variant_coordinate] + alt_variant_coordinate:
+            *v, typ = variant_coordinate  # last column is type ie "dup"
+            hgvs_g = _v2h(*v)
+            hgvs_string = hgvs_g.format()
+            assert hgvs_string == expected_hgvs_string