Interestingly, BRCA1 is not a haploid -
insufficient tumor suppressor gene; therefore monoallelic deletion may not affect its function or affect tumorigenesis of those breast cancers bearing deletions.
These observations support the notion that BECN1 is a haploid -
insufficient tumor suppressor gene and distinguish it from other classic tumor suppressors that require both alleles be inactivated in promoting tumorigenesis.