This case illustrates that methylation of one BRCA1 allele may serve as the second hit in a patient with a diploid locus and missense mutation on the other allele.
Geisler(J P),Rathe(J A),Manahan(K J),Geisler(H E)Methylation: a second hit in the two-hit hypothesis.European journal of gynaecological oncology2003-10-30245