Israel Medical Association Journal

Background: Evaluation of mismatch repair (MMR) deficiency is conducted via immunohistochemistry or by microsatellite instability (MSI) analysis. Heterogeneous immunohistochemistry staining for MMR proteins may show different patterns; however, according to current guidelines, all of those patterns should be interpreted as MMR proficient. This conclusion might lead to false negative results because although most cases of heterogeneity stem from technical factors and biological variability, other types of heterogeneity represent true MMR deficiency.

Objectives: To identify a unique heterogeneity pattern that is associated with true MMR loss.

Methods: We analyzed 145 cases of colorectal carcinoma. Immunohistochemistry staining for MLH1, PMS2, MSH2, and MSH6 were performed. We defined geographic heterogeneity as areas of tumor nuclear staining adjacent to areas of loss of tumor nuclear staining with intact staining in the surrounding stroma. All cases were evaluated for the presence of geographic heterogeneity. In addition, 24 cases were also evaluated by MSI testing.

Results: Of the 145 cases, 24 (16.5%) were MMR deficient. Of the 24 cases for which MSI analysis was also available, 10 cases (41.7%) demonstrated biological heterogeneity, 5 (20.8%) demonstrated technical heterogeneity, and 2 (8.3%) demonstrated geographic heterogeneity. Only the two cases with geographic heterogeneity were MSI-high via MSI analysis. In addition, a germline mutation in MSH-6 was identified in one of these cases.

Conclusions: Geographic heterogeneity may raise a suspicion for a MMR-deficient case, which should be further analyzed using additional methodologies such as MSI analysis.

Background: Patients with multiple (< 100) colorectal adenomatous polyps are at increased risk for colorectal cancer. Genetic evaluation of those patients who test negative for APC gene mutation is both a clinical and economic burden but is critical for counseling and surveillance. In Israel, this is confounded by the fact that national health insurance does not fully cover genetic evaluation of APC gene exon 16.

Objectives: To perform a comprehensive genetic evaluation of APC gene mutation-negative polyposis patients with the aim of developing a future evaluation protocol.

Methods: Genetic analyses were performed in 29 APC gene mutation-negative Jewish individuals with 5 to ≥ 40 colonic adenomas who did not fulfill Amsterdam (clinical) criteria for Lynch syndrome. Analyses included completion of APC gene exon 16 sequencing, analysis for APC gene copy number variations (deletions or duplications), MUTYH gene sequencing, and microsatellite instability in CRC[1] patients fulfilling “Bethesda” (laboratory investigation) criteria for Lynch syndrome.

Results: Completion of APC gene exon 16 sequencing revealed one patient with the E1317Q polymorphism. All were normal by APC multiplex ligation-dependent probe amplification analysis. Pathogenic MUTYH mutations were found in three patients, all of North African origin; two additional patients had variants of unknown significance. One of six patients with Bethesda-positive criteria was MSI²-High with immunohistology consistent with MLH1 mutation.

Conclusions: Based on this small but well-characterized cohort with multiple colorectal adenomas, Lynch syndrome needs to be excluded if there are compatible criteria; otherwise MUTYH sequencing is probably the first step in evaluating APC-negative patients, especially for Jews of North African descent. Completing APC exon 16 sequencing and copy number variations analysis should probably be the last evaluations.

Background: In simultaneous pancreas-kidney transplantation, with both organs coming from the same donor, the addition of a pancreas to the kidney transplant does not jeopardize the kidney allograft outcome despite higher postoperative SPK morbidity. Pancreas allograft outcome has recently improved due to better organ selection and more accurate surgical techniques.

Objective: To demonstrate the positive impact of SPK on kidney allograft outcome versus kidney transplantation alone in insulin-dependent diabetes mellitus patients with end-stage renal failure.

Methods: We performed 39 consecutive SPKs in 14 female and 25 male IDDM patients with renal failure after an average waiting time of 9 months. Multi-organ donor age was 30 years (range 12-53). The kidneys were transplanted in the left retroperitoneal iliac fossa following completion of the pancreas transplantation; kidney cold ischemia time was 16±4 hours. Induction anti-rejection therapy was achieved with polyclonal antithymocytic globulin and methylprednisolone, and maintenance immunosuppression by triple drug therapy (prednisone, cyclosporine or tacrolimus, and azathioprine or mycophenolate mofetil). Infection and rejection were closely monitored.

Results: All kidney allografts produced immediate urinary output following SPK. Two renal grafts had mild function impairment due to acute tubular damage but recovered after a short delay. Three patients died from myocardial infarction, cerebrovascular event and abdominal sepsis on days 1, 32 and 45 respectively (1 year patient survival 92%). An additional kidney allograft was lost due to a renal artery pseudo-aneurysm requiring nephrectomy on day 26. Nineteen patients (49%) had an early rejection of the kidney that was resistant to pulse-steroid therapy in 6. No kidney graft was lost due to rejection. Patients with acute kidney-pancreas rejection episodes suffered from severe infection, which was the main cause of morbidity with a 55% re-admission rate. Complications of the pancreas allograft included graft pancreatitis and sepsis, leading to a poor kidney outcome with sub-optimal kidney function at 1 year. Kidney graft survival at one year was 89% or 95% after censoring the data for patients who died with functioning grafts.

Conclusions: Eligible IDDM patients with advanced diabetic nephropathy should choose SPK over kidney transplantation alone from either a cadaver or a living source.

__________________________________

SPK= simutaneous pancreas-kidney transplatation

IDDM= insulin-dependent diabetes mellitus