Genomic Microsatellite Signatures Identify Germline Mismatch Repair Deficiency and Risk of Cancer Onset.

PURPOSE: Diagnosis of Mismatch Repair Deficiency (MMRD) is crucial for tumor management and early detection in patients with the cancer predisposition syndrome constitutional mismatch repair deficiency (CMMRD). Current diagnostic tools are cumbersome and inconsistent both in childhood cancers and in determining germline MMRD. PATIENTS AND METHODS: We developed and analyzed a functional Low-pass Genomic Instability Characterization (LOGIC) assay to detect MMRD. The diagnostic performance of LOGIC was compared with that of current established assays including tumor mutational burden, immunohistochemistry, and the microsatellite instability panel. LOGIC was then applied to various normal tissues of patients with CMMRD with comprehensive clinical data including age of cancer presentation. RESULTS: Overall, LOGIC was 100% sensitive and specific in detecting MMRD in childhood cancers (N = 376). It was more sensitive than the microsatellite instability panel (14%, P = 4.3 × 10-12), immunohistochemistry (86%, P = 4.6 × 10-3), or tumor mutational burden (80%, P = 9.1 × 10-4). LOGIC was able to distinguish CMMRD from other cancer predisposition syndromes using blood and saliva DNA (P < .0001, n = 277). In normal cells, MMRDness scores differed between tissues (GI > blood > brain), increased over time in the same individual, and revealed genotype-phenotype associations within the mismatch repair genes. Importantly, increased MMRDness score was associated with younger age of first cancer presentation in individuals with CMMRD (P = 2.2 × 10-5). CONCLUSION: LOGIC was a robust tool for the diagnosis of MMRD in multiple cancer types and in normal tissues. LOGIC may inform therapeutic cancer decisions, provide rapid diagnosis of germline MMRD, and support tailored surveillance for individuals with CMMRD.

Survival Benefit for Individuals With Constitutional Mismatch Repair Deficiency Undergoing Surveillance.

PURPOSE: Constitutional mismatch repair deficiency syndrome (CMMRD) is a lethal cancer predisposition syndrome characterized by early-onset synchronous and metachronous multiorgan tumors. We designed a surveillance protocol for early tumor detection in these individuals. PATIENTS AND METHODS: Data were collected from patients with confirmed CMMRD who were registered in the International Replication Repair Deficiency Consortium. Tumor spectrum, efficacy of the surveillance protocol, and malignant transformation of low-grade lesions were examined for the entire cohort. Survival outcomes were analyzed for patients followed prospectively from the time of surveillance implementation. RESULTS: A total of 193 malignant tumors in 110 patients were identified. Median age of first cancer diagnosis was 9.2 years (range: 1.7-39.5 years). For patients undergoing surveillance, all GI and other solid tumors, and 75% of brain cancers were detected asymptomatically. By contrast, only 16% of hematologic malignancies were detected asymptomatically (P < .001). Eighty-nine patients were followed prospectively and used for survival analysis. Five-year overall survival (OS) was 90% (95% CI, 78.6 to 100) and 50% (95% CI, 39.2 to 63.7) when cancer was detected asymptomatically and symptomatically, respectively (P = .001). Patient outcome measured by adherence to the surveillance protocol revealed 4-year OS of 79% (95% CI, 54.8 to 90.9) for patients undergoing full surveillance, 55% (95% CI, 28.5 to 74.5) for partial surveillance, and 15% (95% CI, 5.2 to 28.8) for those not under surveillance (P < .0001). Of the 64 low-grade tumors detected, the cumulative likelihood of transformation from low-to high-grade was 81% for GI cancers within 8 years and 100% for gliomas in 6 years. CONCLUSION: Surveillance and early cancer detection are associated with improved OS for individuals with CMMRD.

Delineating a new feature of constitutional mismatch repair deficiency (CMMRD) syndrome: breast cancer.

Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare autosomal recessive hereditary cancer condition, characterized by an exceptionally high risk of cancer, a propensity for childhood malignancies, and cutaneous features reminiscent of neurofibromatosis type 1 (NF1). We report on two sisters originally suspected of having CMMRD syndrome due to their history of colonic polyps and NF1 associated skin findings, both were subsequently found to have biallelic MSH6 mutations. After years of CMMRD syndrome follow-up, the proband was diagnosed with breast cancer at age 29, while her sister was diagnosed with a glioblastoma at age 27. Immunohistochemistry analysis on the breast tumor tissue revealed weak MSH6 protein staining. Exome sequencing revealed a hypermutated breast tumor and an ultra-hypermutated brain tumor. Multi-gene panel testing was also performed and revealed no additional mutations which might explain the proband's early onset breast cancer. This is the first documented case of breast cancer in an individual with CMMRD syndrome. We summarize the evidence supporting the possible association between breast cancer and biallelic MMR mutations. Healthcare providers should be aware of this possible association and follow-up appropriately for suspicious breast findings. In addition, this case highlights the need for frequent central nervous system screenings due to rapid progression of brain tumors.

The use of the internet in data assimilation in rare diseases.

The incidence and prevalence of achalasia is 0.6/100,000 people per year and 1/10,000, respectively. It is difficult then for one center to accumulate a large cohort of patients. One study (Gut 33:1011,1992) described the presenting symptoms in only 38 patients. To approach this problem differently, we used the internet to access a larger patient population. Using search engines at Google and Yahoo, Inc., we identified achalasia support groups. We examined the most populated support group (YSG) and assembled the exchanged messages into 4 categories: support, symptoms, treatment, and diagnosis. Next, a survey modeled after a previous study (ibid) was composed and posted on a university-sponsored Web site for March 2003, advertised to YSG members, and then removed from the server. The results were entered into a database and analyzed. There were 6 support groups identified; 1 was foreign. The most populated site was the Yahoo, Inc., group with 298 active members. We analyzed the 3,222 messages posted from October 6, 2002 through October 5, 2003. The message composition was as follows: 67% support, 16% symptoms, 12% treatment, and 5% diagnosis. Of 298 Yahoo site members, we had 88 respondents to the survey from 9 countries. The data from 83 were analyzed (5 were not completed). Respondents were 66 women (55%), 29 men (24%), and 5 non-gender-identified respondents. They ranged in age from 6 to 72 years at time of diagnosis. In the 83 respondents, dysphagia symptoms were reported by 98%, regurgitation by 68%, chest pain by 81%, weight loss by 69%, and epigastric pain by 67%, similar to those reported in the study cited in Gut. The modalities used to evaluate these achalasia patients were as follows: 83% had monometry, 87% had radiography, and 89% had endoscopy. The mean time from symptom onset to diagnosis was 5 years. The treatments attempted on this population were balloon dilatation in 57%, botulinum toxin injection (Botox) in 8%, myotomy in 12%, by lifestyle/diet modification in 12%, and other treatments in 11%. We believe that the Internet can provide physician-researchers with useful information about common and uncommon diseases on a global basis. The Internet allows patients to voice concerns that they may not freely express to their doctor and provides a modality to collect data from a larger number of patients than may be available at any single institution.