The penetrance of this gene is assumed to be 95% by the age of 80. The complex segregation analysis used to derive the model assumes that a single, rare, dominantly inherited gene accounts for genetic susceptibility to breast cancer in the general population.
The model dates from before the BRCA1 and BRCA2 genes were identified. A statistical model ( Claus model, named after the author of the study) was developed that estimated the chance that a cancer-predisposition gene was present in a family. This was a study of 4700 women with breast cancer, who had their family history taken. It was derived from the Cancer and Steroid Hormone ("CASH" or "Claus") study (16). This was one of the first of the risk prediction models to be developed.