This webinar will explore how co-segregation can be used as a line of evidence in variant assessment for hereditary cancer genes. Due to the variable penetrance and later-onset phenotypes associated with many cancer syndromes, co-segregation analysis can prove to be a complex endeavor. Reviewing the literature and specific case examples, the presenters will discuss when co-segregation analysis is most useful in VUS resolution for hereditary cancer genes and also when this line of evidence does not garner significant information, or can be misleading, for classification.