Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

HPKM
88691
endometrium, and stomach. Absence of MLH1 and PMS2 protein expression within a tumor, for
instance, is most often associated with a somatic alteration in individuals with an older age of onset of
cancer than typical HNPCC/Lynch syndrome families. Therefore, an MSI-H phenotype or loss of
protein expression by IHC within a tumor does not distinguish between somatic and germline
mutations. Genetic testing of the gene indicated by IHC analysis can help to distinguish between these
two possibilities. In addition, when absence of MLH1/PMS2 are observed, MLBRF/87931 MLH1
Hypermethylation and BRAF Mutation Analyses, Tumor or MLH1H/87978 MLH1 Hypermethylation
Analysis, Tumor may also help to distinguish between a sporadic and germline etiology. It should be
noted that this HNPCC screen is not a genetic test, but rather stratifies the risk of having an inherited
cancer predisposition syndrome, and identifies patients who might benefit from subsequent genetic
testing. See Hereditary Nonpolyposis Colorectal Cancer Testing Algorithm in Special Instructions for
additional information.
Useful For: Identification of individuals at high risk for having hereditary nonpolyposis colon cancer
(HNPCC)/Lynch syndrome
Interpretation: The report will include specimen information, assay information, and interpretation of
test results. Microsatellite stable (MSS) is reported as MSS/MSI-L (0 or 1 of 5 markers demonstrating
instability) or MSI-H (2 or more of 5 markers demonstrating instability).
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Baudhuin LM, Burgart LJ, Leontovich O, Thibodeau SN: Use of
microsatellite instability and immunohistochemistry testing for the identification of individuals at risk for
Lynch Syndrome. Fam Cancer 2005;4(3):255-265 2. Terdiman JP, Gum JR Jr, Conrad PG, et al: Efficient
detection of hereditary nonpolyposis colorectal cancer gene carriers by screening for tumor microsatellite
instability before germline genetic testing. Gastroenterology 2001 January;120(1):21-30
Hereditary Pancreatitis, Known Mutation
Clinical Information: Hereditary pancreatitis (HP) is a rare autosomal dominant disorder, with
approximately 80% penetrance. HP is characterized by early onset of acute pancreatitis during childhood
or early adolescence. The acute pancreatitis in these patients generally progresses to chronic pancreatitis
by adulthood and can eventually lead to both exocrine and endocrine pancreatic insufficiency. Patients
with HP are also at an increased risk for developing pancreatic cancer. Studies have estimated the lifetime
risk of developing pancreatic cancer to be as high as 40%. HP cannot be clinically distinguished from
other forms of pancreatitis. However, PRSS1 mutations are generally restricted to individuals with a
family history of pancreatitis. PRSS1 mutations are infrequently found in patients with alcohol-induced
and tropical pancreatitis. The protease serine 1 or cationic trypsinogen (PRSS1) gene is located on
chromosome 7. It has been reported that as many as 80% of patients with symptomatic hereditary
pancreatitis have a causative PRSS1 mutation. Although several mutations have been identified, the
Arg122His (R122H), Asn29Ile (N29I), and Ala16Val (A16V) mutations have been identified as the
primary causative defects in HP. The phenotype of patients with these 3 mutations is quite similar, sharing
many clinical features, though there are some differences. Data suggests that the R122H mutation results
in more severe disease and earlier onset of symptoms, while the A16V mutation has reduced penetrance.
Although these 3 alterations account for >90% of mutations detected in the cationic trypsinogen gene, the
inability to identify mutations in approximately 20% of families with HP suggests the possible
involvement of other loci or unidentified mutations in the cationic trypsinogen gene.
Useful For: Confirming the diagnosis of hereditary pancreatitis in patients with chronic pancreatitis
who also have a family member with a documented PRSS1 gene mutation Screening of at-risk individuals
when a mutation has been identified in an affected family member
Interpretation: An interpretive report will be provided.
Reference Values:
An interpretive report will be provided.
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