The role of PCGT methylation as a very early event is further supported by our finding that PCGTs were highly enriched among CpGs which were hypermethylated in blood cells from BRCA1 mutation carriers, suggesting that BRCA1 is an important regulator of the DNA methylome and that aberrant BRCA1 function could lead to increased predisposition to cancer through increased methylation at PCGT loci. The gene discussed is BRCA1; the disease is cancer.