The rate of variant discovery continues to surpass the rate of clinicalgrade interpretation. This is a challenge for precision medicine, because fast, reliable access to variant interpretations is necessary to provide well-informed and timely interpretations of test results to patients. ClinVar is a public repository for interpretations of clinical significance and functional effects of variants in any gene and for any disease. Interpretations are submitted by many sources, including clinical testing laboratories, research laboratories, locus-specific databases, expert panels, practice guidelines, as well as OMIM® and GeneReviews™. Collecting variant interpretations in ClinVar depends on integrating data from these different sources, which has several benefits. First, data integration requires standardizing the data from each source. This improves the quality of the data in ClinVar as well as in each of the individual datasets. ClinVar staff validate HGVS expressions as a routine part of ClinVar submission processing. Submitters are encouraged to use standard terms in MedGen for diseases and phenotypes. Standard terms for clinical significance are used in ClinVar when available; for example, ClinVar uses the terms recommended by ACMG to classify variants for Mendelian diseases. Secondly, ClinVar aggregates all data for a variant defined by its genomic location. Therefore, HGVS descriptions on different transcripts or on different genomic sequences can be recognized as the same variant. Thirdly, integrating data from multiple submitters allows the evidence from all sources to be pooled together. This larger collection of evidence aids the re-evaluation of variant classifications, and is especially valuable for rare variants and novel gene-disease relationships. Fourthly, data integration means that variant interpretations from different sources can be viewed together and compared. Thus a ClinVar user has access to interpretations outside any internal system and knows when there is consensus in the interpretation or not. Submitting laboratories use reports of conflicting interpretations in ClinVar to prioritize variants that they should re-evaluate. ClinVar receives data from many data providers, and therefore provides clear attribution to each contributing group, including links to records in LSDBs. Each source may update their submission to ClinVar at any time. For example, a record may be updated when a variant is re-classified or when additional evidence is available to support the interpretation. Submitters may consider providing regular updates to ClinVar to prevent their interpretations from becoming out of date. Submissions to ClinVar describe variants that range in complexity from simple alleles with explicit sequence locations through copy number changes and cytogenetic rearrangements with fuzzy boundaries.