The Molecular Predisposition to Hereditary Nonpolyposis Colon Cancer (HNPCC)

Inclusion Criteria:

1. All patients with a new referral for a diagnosis of colorectal cancer (adenocarcinoma) and/or HNPCC-related cancers at the UTMDACC will be considered potentially eligible for this study regardless of prior treatment.
2. Families maintained at the UTMDACC Hereditary Colon Cancer Registry that have a known germline mutation in a mismatch repair gene or contain two or more first degree relatives diagnosed with CRC and/or any HNPCC-related cancers, one of whom must be less than or equal to 50 years at diagnosis.
3. First-degree and more distant relatives of individuals diagnosed with CRC and/or any HNPCC-related cancers from either of the groups in 1 and 2 (above).
4. Any patient diagnosed with CRC and/or any HNPCC-related cancers less than or equal to 45 years of age.
5. Greater than or equal to age 18 at time of study.
6. Able to provide informed consent to participate in this study indicating that they are aware of the investigational nature, in keeping with the policies of this hospital.
7. Non-HNPCC quartets, defined as parents and two offspring who do not carry a mismatch repair gene mutation. These non-HNPCC quartets should have no personal history of cancer, nor cancer in any first degree relatives of the quartet members, nor history of trinucleotide repeat syndromes. Non-HNPCC parents in a quartet should be less than 34 years old at the time the offspring were born.
8. Lynch Syndrome patients identified and recruited through Protocol PA11-0567 who opt into Optional Procedure B, which consents the patient to participate in this study.

Exclusion Criteria:

1. Diagnosis of current major psychiatric disorder, per DSM-III-R (or DSM IV).
2. Age less than 18 years at time of enrollment.