Basic concepts for genetic testing in common hereditary colorectal cancer syndromes

Can targeted intervention in CRC patients' relatives influence screening behaviour? A pilot study

OBJECTIVE

This study aimed to assess the utility of a standardised risk information tool with respect to the uptake of screening activities administered to an accessible population of first-degree relatives of patients with sporadic colorectal cancer.

METHOD

Patients admitted for colorectal cancer resection were invited to enroll their family unit in the study. Families were randomised either to receive standard care or the intervention tool. The intervention group received a structured one page pamphlet outlining the risk associated with a family history of colorectal cancer, and the availability of and potential benefits from screening. Three months after the initial contact with the index patient, family members were invited to participate in a telephone interview. Primary end-points were both intention to screen and uptake of screening activities.

RESULTS

Forty-seven families had 156 eligible first degree relatives. Ninety-one consented to participate and were enrolled: 59 received standard care, 32 received the intervention. Age and sex were similar between groups. There was no significant difference in previous screening activities. The intervention tool had no influence on perceived self-risk of developing colorectal cancer or uptake of screening activities within the study period.

CONCLUSION

This study suggests that the provision of targeted risk information to first-degree relatives is not likely to positively influence screening behaviour. Health care providers need to find alternative methods of disseminating information to this high-risk group.

A clinician's guide to hereditary colon cancer

Approximately 10% of patients diagnosed with colorectal cancer are at risk for a hereditary form of the disease. At-risk patients can be offered genetic counseling and testing to determine whether they carry a detectable mutation for such a syndrome. If so, this information provides the clinician with valuable data about the patient's risk for other cancers, and what further surveillance and risk reduction options should be incorporated into the management plan. Mutation identification within a family also makes it possible for other family members to learn if they are at risk for the same syndrome. There are many hereditary colorectal cancer syndromes, and the clinician must know what essential information should be elicited from a family history and which patients should be referred for genetic counseling and testing.

The dawn of genetic testing for glaucoma

PURPOSE OF REVIEW

To review recent trends in genetic testing in medicine as they apply to newly evolving tests for patients with glaucoma.

RECENT FINDINGS

The utilization of powerful molecular methods for genetic testing is now entering its early stages in the practice of medicine in general, and with testing, many issues, both medical and societal, have been raised. Only recently has testing for a disease risk factor in primary open angle glaucoma (POAG) become available. It is known that some mutations in the gene myocilin are associated with POAG. MYOC.mt1 is a relatively common promoter region variant in the myocilin gene for which there is a commercially available test. Some investigators have found that MYOC.mt1 may increase disease severity in patients with POAG, whereas others have not found this association. There is a need for further testing for the role of the MYOC.mt1 variant in the pathogenesis of POAG.

SUMMARY

Genetic testing for glaucoma holds great promise. Currently available tests for disease-related tests in patients with glaucoma or at risk for this disease remain controversial.

What is next in pharmacogenomics? Translating it to clinical practice

Pharmacogenomics (PG) holds promise for transforming medical therapeutics but the details of how the promise will become reality are still vague. In this article, we focus on the role that laboratory medicine, as a discipline, might play in transitioning the application of pharmacogenomics into the healthcare system and begin to frame a perspective on how PG may be viewed in this context. Development of clinical diagnostic tests usually evolves as a continuum of information starting with the discovery of a potential biological marker through to its routine use in clinical practice. This process has traditionally been rooted in the practice of laboratory medicine and, importantly, includes the development of testing strategies to optimize the predictive value of single or a combination of biological markers. In this context, we also discuss a perspective on some future strategies that may prove useful in advancing the application of PG, including the need for an evidenced-based approach and the potential role of proteomics as a means to drive more comprehensive strategies.

Loss of IGF2 imprinting: a potential marker of colorectal cancer risk

Loss of imprinting (LOI), an epigenetic alteration affecting the insulin-like growth factor II gene (IGF2), is found in normal colonic mucosa of about 30% of colorectal cancer (CRC) patients, but it is found in only 10% of healthy individuals. In a pilot study to investigate the utility of LOI as a marker of CRC risk, we evaluated 172 patients at a colonoscopy clinic. The adjusted odds ratio for LOI in lymphocytes was 5.15 for patients with a positive family history [95% confidence interval (95% CI), 1.70 to 16.96; probability P = 0.002], 3.46 for patients with adenomas (95% CI, 1.14 to 11.37; P = 0.026), and 21.7 for patients with CRC (95% CI, 3.48 to 153.6; P = 0.0005). LOI can be assayed with a DNA-based blood test, and it may be a valuable predictive marker of an individual's risk for CRC.