[1] The hereditary factors may be proven or suspected to cause the pattern of breast and ovarian cancer occurrences in the family.

Most hereditary breast-ovarian cancer syndromes are inherited in an autosomal dominant pattern.

Biallelic and homozygous inheritance of defective alleles that confer this syndrome is usually an embryonically lethal condition; live cases usually experience a severe form of Fanconi anemia.

Live cases suffer from a severe form of Fanconi Anemia; biallelic mutations of BRCA1 lead to Fanconi anemia complementation group S, and biallelic mutations of BRCA2 lead to complementation group D1.

[6] An increasing number women who test positive for faulty BRCA1 or BRCA2 genes choose to have risk-reducing surgery.