A panel of 5 microsatellite markers was proposed in the original Bethesda guidelines to describe microsatellite instability (MSI) in hereditary nonpolyposis colorectal cancer (HNPCC) syndrome.
Components of the Bethesda panel:
(1) BAT-25 (mononucleotide repeat)
(2) BAT-26 (mononucleotide repeat)
(3) D2S123 (dinucelotide repeat)
(4) D5S346 (dinucelotide repeat)
(5) D17S250 (dinucelotide repeat)
|
Marker |
Finding |
Points |
|
BAT-25 |
stable |
0 |
|
|
unstable (mutated) |
1 |
|
BAT-26 |
stable |
0 |
|
|
unstable (mutated) |
1 |
|
D2S125 |
stable |
0 |
|
|
unstable (mutated) |
1 |
|
D5S346 |
stable |
0 |
|
|
unstable (mutated) |
1 |
|
D17S250 |
stable |
0 |
|
|
unstable (mutated) |
1 |
total score =
= SUM(points for all 5 parameters)
Interpretation:
• minimum score: 0
• maximum score: 5
|
Total Score |
Microsatellite Instability (MSI) |
|
0 |
MSI stable (MSS) |
|
1 |
MSI low (MSI-L) |
|
2- 5 |
MSI high (MSI-H) |
These criteria were modified at the 2002 Bethesda conference:
(1) If dinucleotide repeat markers are mutated then the patient should be tested for additional mononucleotide repeat markers (BAT40 and/or MYCL). This is because the dinucleotide repeats are less sensitive for the detection of MSI-H.
(2) An alternative panel of 5 quasimonomorphic mononucleotide repeats may be more sensitive for the detection of MSI-H. If this panel is used, then a score >= 3 indicates MSI-H.
where:
• The recommendation to do additional testing may only apply if a single dinculeotide repeat marker is mutated.
Purpose: To detect microsatellite instability (MSI) in a colorectal carcinoma using the Bethesda panel.
Specialty: Hematology Oncology, Surgery, general, Gastroenterology
Objective: laboratory tests
ICD-10: C18.9,
