1 package jalview.io.vcf;
3 import htsjdk.samtools.util.CloseableIterator;
4 import htsjdk.variant.variantcontext.Allele;
5 import htsjdk.variant.variantcontext.VariantContext;
6 import htsjdk.variant.vcf.VCFHeader;
7 import htsjdk.variant.vcf.VCFHeaderLine;
8 import htsjdk.variant.vcf.VCFHeaderLineCount;
9 import htsjdk.variant.vcf.VCFInfoHeaderLine;
11 import jalview.analysis.AlignmentUtils;
12 import jalview.analysis.Dna;
13 import jalview.api.AlignViewControllerGuiI;
14 import jalview.datamodel.AlignmentI;
15 import jalview.datamodel.DBRefEntry;
16 import jalview.datamodel.GeneLociI;
17 import jalview.datamodel.Mapping;
18 import jalview.datamodel.SequenceFeature;
19 import jalview.datamodel.SequenceI;
20 import jalview.ext.ensembl.EnsemblMap;
21 import jalview.ext.htsjdk.VCFReader;
22 import jalview.io.gff.Gff3Helper;
23 import jalview.io.gff.SequenceOntologyI;
24 import jalview.util.MapList;
25 import jalview.util.MappingUtils;
26 import jalview.util.MessageManager;
28 import java.io.IOException;
29 import java.util.ArrayList;
30 import java.util.HashMap;
31 import java.util.List;
33 import java.util.Map.Entry;
36 * A class to read VCF data (using the htsjdk) and add variants as sequence
37 * features on dna and any related protein product sequences
41 public class VCFLoader
44 * keys to fields of VEP CSQ consequence data
45 * see https://www.ensembl.org/info/docs/tools/vep/vep_formats.html
47 private static final String ALLELE_NUM_KEY = "ALLELE_NUM"; // 0 (ref), 1...
49 private static final String FEATURE_KEY = "Feature"; // Ensembl stable id
52 * default VCF INFO key for VEP consequence data
53 * NB this can be overridden running VEP with --vcf_info_field
54 * - we don't handle this case (require CSQ identifier)
56 private static final String CSQ = "CSQ";
59 * separator for fields in consequence data
61 private static final String PIPE = "|";
63 private static final String PIPE_REGEX = "\\" + PIPE;
66 * key for Allele Frequency output by VEP
67 * see http://www.ensembl.org/info/docs/tools/vep/vep_formats.html
69 private static final String ALLELE_FREQUENCY_KEY = "AF";
72 * delimiter that separates multiple consequence data blocks
74 private static final String COMMA = ",";
77 * (temporary) flag that determines whether Jalview adds one feature
78 * per VCF record, or one per allele (preferred)
80 private static final boolean FEATURE_PER_ALLELE = true;
83 * the feature group assigned to a VCF variant in Jalview
85 private static final String FEATURE_GROUP_VCF = "VCF";
88 * internal delimiter used to build keys for assemblyMappings
91 private static final String EXCL = "!";
94 * the alignment we are associating VCF data with
96 private AlignmentI al;
99 * mappings between VCF and sequence reference assembly regions, as
100 * key = "species!chromosome!fromAssembly!toAssembly
101 * value = Map{fromRange, toRange}
103 private Map<String, Map<int[], int[]>> assemblyMappings;
106 * holds details of the VCF header lines (metadata)
108 private VCFHeader header;
111 * the position (0...) of the ALLELE_NUM field in each block of
112 * CSQ (consequence) data (if declared in the VCF INFO header for CSQ)
113 * see http://www.ensembl.org/info/docs/tools/vep/vep_formats.html
115 private int csqAlleleNumberFieldIndex = -1;
117 private int csqFeatureFieldIndex = -1;
120 * Constructor given an alignment context
124 public VCFLoader(AlignmentI alignment)
128 // map of species!chromosome!fromAssembly!toAssembly to {fromRange, toRange}
129 assemblyMappings = new HashMap<String, Map<int[], int[]>>();
133 * Starts a new thread to query and load VCF variant data on to the alignment
135 * This method is not thread safe - concurrent threads should use separate
136 * instances of this class.
141 public void loadVCF(final String filePath,
142 final AlignViewControllerGuiI gui)
146 gui.setStatus(MessageManager.getString("label.searching_vcf"));
155 VCFLoader.this.doLoad(filePath, gui);
162 * Loads VCF on to an alignment - provided it can be related to one or more
163 * sequence's chromosomal coordinates
167 * optional callback handler for messages
169 protected void doLoad(String filePath, AlignViewControllerGuiI gui)
171 VCFReader reader = null;
174 // long start = System.currentTimeMillis();
175 reader = new VCFReader(filePath);
177 header = reader.getFileHeader();
178 VCFHeaderLine ref = header
179 .getOtherHeaderLine(VCFHeader.REFERENCE_KEY);
182 * note offset of CSQ ALLELE_NUM field if it is declared
186 // check if reference is wrt assembly19 (GRCh37)
187 // todo may need to allow user to specify reference assembly?
188 boolean isRefGrch37 = (ref != null && ref.getValue().contains(
195 * query for VCF overlapping each sequence in turn
197 for (SequenceI seq : al.getSequences())
199 int added = loadVCF(seq, reader, isRefGrch37);
204 transferAddedFeatures(seq);
209 // long elapsed = System.currentTimeMillis() - start;
210 String msg = MessageManager.formatMessage("label.added_vcf",
213 if (gui.getFeatureSettingsUI() != null)
215 gui.getFeatureSettingsUI().discoverAllFeatureData();
218 } catch (Throwable e)
220 System.err.println("Error processing VCF: " + e.getMessage());
224 gui.setStatus("Error occurred - see console for details");
233 } catch (IOException e)
242 * Records the position of fields for ALLELE_NUM and Feature defined in the
243 * CSQ INFO header (if there is one). CSQ fields are declared in the CSQ INFO
246 * Description="Consequence ...from ... VEP. Format: Allele|Consequence|...
248 protected void locateCsqFields()
250 VCFInfoHeaderLine csqInfo = header.getInfoHeaderLine(CSQ);
256 String desc = csqInfo.getDescription();
259 String[] format = desc.split(PIPE_REGEX);
261 for (String field : format)
263 if (ALLELE_NUM_KEY.equals(field))
265 csqAlleleNumberFieldIndex = index;
267 if (FEATURE_KEY.equals(field))
269 csqFeatureFieldIndex = index;
277 * Transfers VCF features to sequences to which this sequence has a mapping.
278 * If the mapping is 1:3, computes peptide variants from nucleotide variants.
282 protected void transferAddedFeatures(SequenceI seq)
284 DBRefEntry[] dbrefs = seq.getDBRefs();
289 for (DBRefEntry dbref : dbrefs)
291 Mapping mapping = dbref.getMap();
292 if (mapping == null || mapping.getTo() == null)
297 SequenceI mapTo = mapping.getTo();
298 MapList map = mapping.getMap();
299 if (map.getFromRatio() == 3)
302 * dna-to-peptide product mapping
304 AlignmentUtils.computeProteinFeatures(seq, mapTo, map);
309 * nucleotide-to-nucleotide mapping e.g. transcript to CDS
311 List<SequenceFeature> features = seq.getFeatures()
312 .getPositionalFeatures(SequenceOntologyI.SEQUENCE_VARIANT);
313 for (SequenceFeature sf : features)
315 if (FEATURE_GROUP_VCF.equals(sf.getFeatureGroup()))
317 transferFeature(sf, mapTo, map);
325 * Tries to add overlapping variants read from a VCF file to the given
326 * sequence, and returns the number of variant features added. Note that this
327 * requires the sequence to hold information as to its chromosomal positions
328 * and reference, in order to be able to map the VCF variants to the sequence.
332 * @param isVcfRefGrch37
335 protected int loadVCF(SequenceI seq, VCFReader reader,
336 boolean isVcfRefGrch37)
339 GeneLociI seqCoords = seq.getGeneLoci();
340 if (seqCoords == null)
345 List<int[]> seqChromosomalContigs = seqCoords.getMap().getToRanges();
346 for (int[] range : seqChromosomalContigs)
348 count += addVcfVariants(seq, reader, range, isVcfRefGrch37);
355 * Queries the VCF reader for any variants that overlap the given chromosome
356 * region of the sequence, and adds as variant features. Returns the number of
357 * overlapping variants found.
362 * start-end range of a sequence region in its chromosomal
364 * @param isVcfRefGrch37
365 * true if the VCF is with reference to GRCh37
368 protected int addVcfVariants(SequenceI seq, VCFReader reader,
369 int[] range, boolean isVcfRefGrch37)
371 GeneLociI seqCoords = seq.getGeneLoci();
373 String chromosome = seqCoords.getChromosomeId();
374 String seqRef = seqCoords.getAssemblyId();
375 String species = seqCoords.getSpeciesId();
378 * map chromosomal coordinates from GRCh38 (sequence) to
379 * GRCh37 (VCF) if necessary
381 // TODO generalise for other assemblies and species
383 String fromRef = "GRCh38";
384 if (fromRef.equalsIgnoreCase(seqRef) && isVcfRefGrch37)
386 String toRef = "GRCh37";
387 int[] newRange = mapReferenceRange(range, chromosome, "human",
389 if (newRange == null)
391 System.err.println(String.format(
392 "Failed to map %s:%s:%s:%d:%d to %s", species, chromosome,
393 fromRef, range[0], range[1], toRef));
396 offset = newRange[0] - range[0];
400 boolean forwardStrand = range[0] <= range[1];
403 * query the VCF for overlaps
404 * (convert a reverse strand range to forwards)
407 MapList mapping = seqCoords.getMap();
409 int fromLocus = Math.min(range[0], range[1]);
410 int toLocus = Math.max(range[0], range[1]);
411 CloseableIterator<VariantContext> variants = reader.query(chromosome,
413 while (variants.hasNext())
416 * get variant location in sequence chromosomal coordinates
418 VariantContext variant = variants.next();
421 * we can only process SNP variants (which can be reported
422 * as part of a MIXED variant record
424 if (!variant.isSNP() && !variant.isMixed())
429 int start = variant.getStart() - offset;
430 int end = variant.getEnd() - offset;
433 * convert chromosomal location to sequence coordinates
434 * - null if a partially overlapping feature
436 int[] seqLocation = mapping.locateInFrom(start, end);
437 if (seqLocation != null)
439 count += addVariantFeature(seq, variant, seqLocation[0],
440 seqLocation[1], forwardStrand);
450 * Inspects the VCF variant record, and adds variant features to the sequence.
451 * Only SNP variants are added, not INDELs. Returns the number of features
454 * If the sequence maps to the reverse strand of the chromosome, reference and
455 * variant bases are recorded as their complements (C/G, A/T).
459 * @param featureStart
461 * @param forwardStrand
463 protected int addVariantFeature(SequenceI seq, VariantContext variant,
464 int featureStart, int featureEnd, boolean forwardStrand)
466 byte[] reference = variant.getReference().getBases();
467 if (reference.length != 1)
470 * sorry, we don't handle INDEL variants
475 if (FEATURE_PER_ALLELE)
477 return addAlleleFeatures(seq, variant, featureStart, featureEnd,
482 * for now we extract allele frequency as feature score; note
483 * this attribute is String for a simple SNP, but List<String> if
484 * multiple alleles at the locus; we extract for the simple case only
486 float score = getAlleleFrequency(variant, 0);
488 StringBuilder sb = new StringBuilder();
489 sb.append(forwardStrand ? (char) reference[0] : complement(reference));
492 * inspect alleles and record SNP variants (as the variant
493 * record could be MIXED and include INDEL and SNP alleles)
494 * warning: getAlleles gives no guarantee as to the order
495 * in which they are returned
497 for (Allele allele : variant.getAlleles())
499 if (!allele.isReference())
501 byte[] alleleBase = allele.getBases();
502 if (alleleBase.length == 1)
504 sb.append(COMMA).append(
505 forwardStrand ? (char) alleleBase[0]
506 : complement(alleleBase));
510 String alleles = sb.toString(); // e.g. G,A,C
512 String type = SequenceOntologyI.SEQUENCE_VARIANT;
514 SequenceFeature sf = new SequenceFeature(type, alleles, featureStart,
515 featureEnd, score, FEATURE_GROUP_VCF);
517 sf.setValue(Gff3Helper.ALLELES, alleles);
519 Map<String, Object> atts = variant.getAttributes();
520 for (Entry<String, Object> att : atts.entrySet())
522 sf.setValue(att.getKey(), att.getValue());
524 seq.addSequenceFeature(sf);
530 * A convenience method to get the AF value for the given alternate allele
537 protected float getAlleleFrequency(VariantContext variant, int alleleIndex)
540 String attributeValue = getAttributeValue(variant,
541 ALLELE_FREQUENCY_KEY, alleleIndex);
542 if (attributeValue != null)
546 score = Float.parseFloat(attributeValue);
547 } catch (NumberFormatException e)
557 * A convenience method to get an attribute value for an alternate allele
560 * @param attributeName
564 protected String getAttributeValue(VariantContext variant,
565 String attributeName, int alleleIndex)
567 Object att = variant.getAttribute(attributeName);
569 if (att instanceof String)
573 else if (att instanceof ArrayList)
575 return ((List<String>) att).get(alleleIndex);
582 * Adds one variant feature for each SNP allele in the VCF variant record, and
583 * returns the number of features added.
587 * @param featureStart
589 * @param forwardStrand
592 protected int addAlleleFeatures(SequenceI seq, VariantContext variant,
593 int featureStart, int featureEnd, boolean forwardStrand)
598 * Javadoc says getAlternateAlleles() imposes no order on the list returned
599 * so we proceed defensively to get them in strict order
601 int altAlleleCount = variant.getAlternateAlleles().size();
602 for (int i = 0; i < altAlleleCount; i++)
604 added += addAlleleFeature(seq, variant, i, featureStart, featureEnd,
611 * Inspects one allele and attempts to add a variant feature for it to the
612 * sequence. Only SNP variants are added as features. We extract as much as
613 * possible of the additional data associated with this allele to store in the
614 * feature's key-value map. Answers the number of features added (0 or 1).
618 * @param altAlleleIndex
619 * @param featureStart
621 * @param forwardStrand
624 protected int addAlleleFeature(SequenceI seq, VariantContext variant,
625 int altAlleleIndex, int featureStart, int featureEnd,
626 boolean forwardStrand)
628 byte[] reference = variant.getReference().getBases();
629 Allele alt = variant.getAlternateAllele(altAlleleIndex);
630 byte[] allele = alt.getBases();
631 if (allele.length != 1)
640 * build the ref,alt allele description e.g. "G,A"
642 StringBuilder sb = new StringBuilder();
643 sb.append(forwardStrand ? (char) reference[0] : complement(reference));
645 sb.append(forwardStrand ? (char) allele[0] : complement(allele));
646 String alleles = sb.toString(); // e.g. G,A
648 String type = SequenceOntologyI.SEQUENCE_VARIANT;
649 float score = getAlleleFrequency(variant, altAlleleIndex);
651 SequenceFeature sf = new SequenceFeature(type, alleles, featureStart,
652 featureEnd, score, FEATURE_GROUP_VCF);
654 sf.setValue(Gff3Helper.ALLELES, alleles);
656 addAlleleProperties(variant, seq, sf, altAlleleIndex);
658 seq.addSequenceFeature(sf);
664 * Add any allele-specific VCF key-value data to the sequence feature
669 * @param altAlelleIndex
671 protected void addAlleleProperties(VariantContext variant, SequenceI seq,
672 SequenceFeature sf, final int altAlelleIndex)
674 Map<String, Object> atts = variant.getAttributes();
676 for (Entry<String, Object> att : atts.entrySet())
678 String key = att.getKey();
681 * extract Consequence data (if present) that we are able to
682 * associated with the allele for this variant feature
684 if (CSQ.equals(key) && csqAlleleNumberFieldIndex > -1)
686 addConsequences(att.getValue(), seq, sf, altAlelleIndex + 1);
691 * we extract values for other data which are allele-specific;
692 * these may be per alternate allele (INFO[key].Number = 'A')
693 * or per allele including reference (INFO[key].Number = 'R')
695 VCFInfoHeaderLine infoHeader = header.getInfoHeaderLine(key);
696 if (infoHeader == null)
699 * can't be sure what data belongs to this allele, so
700 * play safe and don't take any
705 VCFHeaderLineCount number = infoHeader.getCountType();
706 int index = altAlelleIndex;
707 if (number == VCFHeaderLineCount.R)
710 * one value per allele including reference, so bump index
711 * e.g. the 3rd value is for the 2nd alternate allele
715 else if (number != VCFHeaderLineCount.A)
718 * don't save other values as not allele-related
724 * take the index'th value
726 String value = getAttributeValue(variant, key, index);
729 sf.setValue(key, value);
735 * Inspects CSQ data blocks (consequences) and adds attributes on the sequence
736 * feature for the current allele (and transcript if applicable)
738 * Allele matching: we require field ALLELE_NUM to match altAlleleIndex. If
739 * the CSQ data does not include ALLELE_NUM values then no data is added to
740 * the variant feature.
742 * Transcript matching: if sequence name can be identified to at least one of
743 * the consequences' Feature values, then select only consequences that match
744 * the value (i.e. consequences for the current transcript sequence). If not,
745 * take all consequences (this is the case when adding features to the gene
751 * @param altAlelleIndex
752 * (1=first alternative allele...)
754 protected void addConsequences(Object value, SequenceI seq,
755 SequenceFeature sf, int altAlelleIndex)
757 if (!(value instanceof ArrayList<?>))
762 List<String> consequences = (List<String>) value;
765 * if CSQ data includes 'Feature', and any value matches the sequence name,
766 * then restrict consequence data to the matching value (transcript)
767 * i.e. just pick out consequences for the transcript the variant feature is on
769 String seqName = seq.getName()== null ? "" : seq.getName().toLowerCase();
770 boolean matchFeature = false;
771 String matchFeatureValue = null;
772 if (csqFeatureFieldIndex > -1)
774 for (String consequence : consequences)
776 String[] csqFields = consequence.split(PIPE_REGEX);
777 if (csqFields.length > csqFeatureFieldIndex)
779 String featureIdentifier = csqFields[csqFeatureFieldIndex];
780 if (featureIdentifier.length() > 4
781 && seqName.indexOf(featureIdentifier.toLowerCase()) > -1)
784 matchFeatureValue = featureIdentifier;
790 StringBuilder sb = new StringBuilder(128);
791 boolean found = false;
793 for (String consequence : consequences)
795 String[] csqFields = consequence.split(PIPE_REGEX);
798 * check consequence is for the current transcript
802 if (csqFields.length <= csqFeatureFieldIndex)
806 String featureIdentifier = csqFields[csqFeatureFieldIndex];
807 if (!featureIdentifier.equals(matchFeatureValue))
809 continue; // consequence is for a different transcript
813 if (csqFields.length > csqAlleleNumberFieldIndex)
815 String alleleNum = csqFields[csqAlleleNumberFieldIndex];
816 if (String.valueOf(altAlelleIndex).equals(alleleNum))
823 sb.append(consequence);
830 sf.setValue(CSQ, sb.toString());
835 * A convenience method to complement a dna base and return the string value
841 protected String complement(byte[] reference)
843 return String.valueOf(Dna.getComplement((char) reference[0]));
847 * Determines the location of the query range (chromosome positions) in a
848 * different reference assembly.
850 * If the range is just a subregion of one for which we already have a mapping
851 * (for example, an exon sub-region of a gene), then the mapping is just
852 * computed arithmetically.
854 * Otherwise, calls the Ensembl REST service that maps from one assembly
855 * reference's coordinates to another's
858 * start-end chromosomal range in 'fromRef' coordinates
862 * assembly reference for the query coordinates
864 * assembly reference we wish to translate to
865 * @return the start-end range in 'toRef' coordinates
867 protected int[] mapReferenceRange(int[] queryRange, String chromosome,
868 String species, String fromRef, String toRef)
871 * first try shorcut of computing the mapping as a subregion of one
872 * we already have (e.g. for an exon, if we have the gene mapping)
874 int[] mappedRange = findSubsumedRangeMapping(queryRange, chromosome,
875 species, fromRef, toRef);
876 if (mappedRange != null)
882 * call (e.g.) http://rest.ensembl.org/map/human/GRCh38/17:45051610..45109016:1/GRCh37
884 EnsemblMap mapper = new EnsemblMap();
885 int[] mapping = mapper.getMapping(species, chromosome, fromRef, toRef,
890 // mapping service failure
895 * save mapping for possible future re-use
897 String key = makeRangesKey(chromosome, species, fromRef, toRef);
898 if (!assemblyMappings.containsKey(key))
900 assemblyMappings.put(key, new HashMap<int[], int[]>());
903 assemblyMappings.get(key).put(queryRange, mapping);
909 * If we already have a 1:1 contiguous mapping which subsumes the given query
910 * range, this method just calculates and returns the subset of that mapping,
911 * else it returns null. In practical terms, if a gene has a contiguous
912 * mapping between (for example) GRCh37 and GRCh38, then we assume that its
913 * subsidiary exons occupy unchanged relative positions, and just compute
914 * these as offsets, rather than do another lookup of the mapping.
916 * If in future these assumptions prove invalid (e.g. for bacterial dna?!),
917 * simply remove this method or let it always return null.
919 * Warning: many rapid calls to the /map service map result in a 429 overload
929 protected int[] findSubsumedRangeMapping(int[] queryRange, String chromosome,
930 String species, String fromRef, String toRef)
932 String key = makeRangesKey(chromosome, species, fromRef, toRef);
933 if (assemblyMappings.containsKey(key))
935 Map<int[], int[]> mappedRanges = assemblyMappings.get(key);
936 for (Entry<int[], int[]> mappedRange : mappedRanges.entrySet())
938 int[] fromRange = mappedRange.getKey();
939 int[] toRange = mappedRange.getValue();
940 if (fromRange[1] - fromRange[0] == toRange[1] - toRange[0])
943 * mapping is 1:1 in length, so we trust it to have no discontinuities
945 if (MappingUtils.rangeContains(fromRange, queryRange))
948 * fromRange subsumes our query range
950 int offset = queryRange[0] - fromRange[0];
951 int mappedRangeFrom = toRange[0] + offset;
952 int mappedRangeTo = mappedRangeFrom + (queryRange[1] - queryRange[0]);
953 return new int[] { mappedRangeFrom, mappedRangeTo };
962 * Transfers the sequence feature to the target sequence, locating its start
963 * and end range based on the mapping. Features which do not overlap the
964 * target sequence are ignored.
967 * @param targetSequence
969 * mapping from the feature's coordinates to the target sequence
971 protected void transferFeature(SequenceFeature sf,
972 SequenceI targetSequence, MapList mapping)
974 int[] mappedRange = mapping.locateInTo(sf.getBegin(), sf.getEnd());
976 if (mappedRange != null)
978 String group = sf.getFeatureGroup();
979 int newBegin = Math.min(mappedRange[0], mappedRange[1]);
980 int newEnd = Math.max(mappedRange[0], mappedRange[1]);
981 SequenceFeature copy = new SequenceFeature(sf, newBegin, newEnd,
982 group, sf.getScore());
983 targetSequence.addSequenceFeature(copy);
988 * Formats a ranges map lookup key
996 protected static String makeRangesKey(String chromosome, String species,
997 String fromRef, String toRef)
999 return species + EXCL + chromosome + EXCL + fromRef + EXCL