Name of the Procedure:

MLH1 (mutL homolog 1, colon cancer, nonpolyposis type 2) gene analysis; duplication/deletion variants
Common name(s): MLH1 gene testing, Lynch syndrome genetic testing

Summary

This procedure involves analyzing the MLH1 gene to detect any duplications or deletions that might lead to hereditary non-polyposis colorectal cancer (Lynch syndrome). The analysis can help determine if a person is at higher risk for developing certain types of cancer, guiding further preventative measures or treatments.

Purpose

The primary purpose of this gene analysis is to identify individuals who may have Lynch syndrome, a hereditary condition that significantly increases the risk of colorectal cancer and other cancers. The goal is to enable early detection and intervention, potentially reducing cancer risk and improving outcomes.

Indications

• Family history of Lynch syndrome or colorectal cancer
• Early-onset colorectal cancer (before age 50)
• Multiple primary cancers (especially if they include colorectal, endometrial, or other Lynch syndrome-related cancers)
• Known familial MLH1 gene mutations

Preparation

• No specific fasting or medication adjustments are usually required.
• A detailed medical and family history for the genetic counselor or physician.
• Possibly a prior genetic counseling session to understand the implications of the test results.

Procedure Description

Step-by-Step Explanation:

1. Sample Collection: Typically involves drawing a blood sample, or occasionally, a saliva sample.
2. Laboratory Analysis: The sample is sent to a genetic lab where experts analyze the MLH1 gene for any duplications or deletions using techniques like multiplex ligation-dependent probe amplification (MLPA) or next-generation sequencing (NGS).
3. Result Interpretation: A geneticist interprets the findings and reports any significant variants.

Tools, Equipment, or Technology Used:

• Blood collection kit
• Saliva collection kit (optional)
• Genetic sequencing machines

Anesthesia or Sedation:

• Not required for the procedure.

Duration

Approximately 15-30 minutes for sample collection. The lab analysis can take a few weeks to complete.

Setting

The blood or saliva sample collection is typically performed in a hospital, outpatient clinic, or specialized genetic testing center.

Personnel

• Phlebotomist or nurse for sample collection
• Genetic counselor or medical geneticist for interpretation and patient counseling

Risks and Complications

• Common: Minor discomfort from blood draw (bruising, slight pain)
• Rare: Infection at the needle site

Benefits

• Identification of Lynch syndrome, leading to personalized cancer surveillance and prevention strategies.
• Informed decision-making for patient and family members regarding their health and lifestyle.

Recovery

• Immediate post-procedure care involves minimal recovery. Patients can usually resume normal activities right away.
• Follow-up: Genetic counseling session to discuss the results and determine the next steps.

Alternatives

• BRCA gene testing for hereditary breast and ovarian cancer syndromes.
• Whole-exome or whole-genome sequencing for broader genetic analysis.
• Pros and Cons: MLH1 gene testing is specifically targeted and may not uncover other genetic risks, whereas broader tests might reveal additional information but at higher cost and complexity.

Patient Experience

During the procedure:

• Blood draw may cause slight discomfort.

After the procedure:

• Results discussion with a genetic counselor to understand the implications.
• Psychological impact of knowing genetic risk, supported by counseling.

Pain Management and Comfort Measures:

• Distraction techniques or topical anesthetics can be used to minimize discomfort during blood draw.