In-frame deletion of 3 nucleotides resulting in deletion of a histidine residue but preserves reading frame. In silico analysis shows that H1673 is in the BRCT domain predicted to interact with the BRCT domain of BARD1. Variant is absent in human variation databases. Loss of BRCA1 WT-allele in 6 ovarian cancers and 2 breast cancers. 2,263,474:1 in favour of causality using Goldgar multifactorial likelihood method (55). This evidence concerns the gene BRCA1 and breast cancer.