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HNPCC/Lynch Syndrome (MLH1) Sequencing and Deletion/Duplication
MessageARUP Lab
Test Code
51650
Alias/See Also
MLH1 FGA
CPT Codes
81292, 81294
Preferred Specimen
Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B) 3 mL
Minimum Volume
1 mL
Instructions
"Transport 3 mL whole blood. (Min: 1 mL) Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
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Transport Temperature
Refrigerated
Specimen Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Methodology
Polymerase Chain Reaction/Sequencing/Multiplex Ligation-dependent Probe Amplification
Setup Schedule
Varies
Report Available
Within 35 days
Limitations
"Diagnostic errors can occur due to rare sequence variations. The breakpoints of large deletions/duplications will not be determined. Regulatory region mutations, deep intronic mutations and mutations in genes other than MLH1 will not be detected.
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Clinical Significance
"Detect germline MLH1 mutations, diagnostic for Lynch syndrome. Background Information for HNPCC/Lynch Syndrome (MLH1) Sequencing and Deletion/Duplication:
Characteristics: Increased risk of colorectal and extra-colonic cancers including endometrial, renal pelvis, ureter, ovary, stomach, small intestine, and hepatobiliary tract.
Incidence: 1-2 percent of colorectal cancer is due to mismatch repair gene mutations.
Inheritance: Autosomal dominant
Penetrance of MLH1 Mutations: 80 percent lifetime risk of colorectal cancer; 20-60 percent risk for endometrial cancer.
Cause: Pathogenic germline MLH1, MSH2, MSH6, and PMS2 gene mutations.
Gene Tested:MLH1
Clinical Sensitivity: Approximately 45 percent of Lynch syndrome is due to MLH1 mutations.
Methodology: Bidirectional sequencing of MLH1 coding regions and intron-exon boundaries; multiplex ligation-dependent probe amplification (MLPA) to detect large MLH1 exonic deletions.Analytical Sensitivity & Specificity: 99 percent"
Characteristics: Increased risk of colorectal and extra-colonic cancers including endometrial, renal pelvis, ureter, ovary, stomach, small intestine, and hepatobiliary tract.
Incidence: 1-2 percent of colorectal cancer is due to mismatch repair gene mutations.
Inheritance: Autosomal dominant
Penetrance of MLH1 Mutations: 80 percent lifetime risk of colorectal cancer; 20-60 percent risk for endometrial cancer.
Cause: Pathogenic germline MLH1, MSH2, MSH6, and PMS2 gene mutations.
Gene Tested:MLH1
Clinical Sensitivity: Approximately 45 percent of Lynch syndrome is due to MLH1 mutations.
Methodology: Bidirectional sequencing of MLH1 coding regions and intron-exon boundaries; multiplex ligation-dependent probe amplification (MLPA) to detect large MLH1 exonic deletions.Analytical Sensitivity & Specificity: 99 percent"
