BRCA2 minor transcript lacking exons4-7 supports viability in mice and may account for survival of humans with a pathogenic biallelic mutation — BRCA2 minor transcript lacking exons 4–7 supports viability in mice and may account for survival of humans with a pathogenic biallelic mutation — BRCA2 minor transcript lacking exons 4–7 supports viability in mice and may account for survival of humans with a pathogenic biallelic mutation