BRCA2 and breast cancer: We also identified truncating variants in chromatid cohesion REC8, whose protein product binds sister chromatids during meiosis, and HMMR (hyaluronan mediated mobility receptor), which encodes for a cell motility protein that forms a complex with tumor suppressors BRCA1 and BRCA2. Common missense variations in HMMR have been shown to modify the penetrance of breast cancer risk in BRCA1 pathogenic mutation carriers[34].