Table 2

Carrier risk classification among the descendants of progenitors.

All systems of risk classification aim to quantitate risk of carrying an HNPCC or HBOC associated mutation. A person is assigned to the first (as listed) appropriate risk category for cancer based and mutation test based risk. Final carrier risk was equal to the higher of the two values (cancer based risk and mutation based risk), except when mutation based risk was zero, in which case final risk was zero. All descendants of progenitors were assigned a final carrier risk.
Cancer based carrier risk. All descendants of progenitors are classified, and mutation test results are ignored
100%Affected with any syndrome cancer (see definitions) or having a descendant affected with a syndrome cancer
50%Having a first degree relative with cancer based carrier risk=100%
25%Having a first degree relative with cancer based carrier risk=50%
LowAll other family members descended from the progenitors
Mutation test based risk. Only family members in branches with tested mutation carriers are classified
0%Being a known non-carrier (see definitions) or an inferred non-carrier (based on known non-carrier ancestors)
100%Being a known carrier (see definitions) or an inferred carrier (based on known carrier descendants)
50%Having a first degree relative with mutation test based carrier risk=100%
25%Having a first degree relative with mutation test based carrier risk=50%
LowAny other member of the family in a branch with some mutation tested positive cases