Papillary thyroid cancer in a patient with MUTYH-associated polyposis (MAP)

Phenotype correlations with pathogenic DNA variants in the MUTYH gene

MUTYH -associated polyposis (MAP) is an autosomal recessive disorder where the inheritance of constitutional biallelic pathogenic MUTYH variants predisposes a person to the development of adenomas and colorectal cancer (CRC). It is also associated with extracolonic and extraintestinal manifestations that may overlap with the phenotype of familial adenomatous polyposis (FAP). Currently, there are discrepancies in the literature regarding whether certain phenotypes are truly associated with MAP. This narrative review aims to explore the phenotypic spectrum of MAP to better characterise the MAP phenotype. A literature search was conducted to identify articles reporting on MAP-specific phenotypes. Clinical data from 2109 MAP patients identified from the literature showed that 1123 patients (53.2%) had CRC. Some patients with CRC had no associated adenomas, suggesting that adenomas are not an obligatory component of MAP. Carriers of the two missense founder variants, and possibly truncating variants, had an increased cancer risk when compared to those who carry other pathogenic variants. It has been suggested that somatic G:C>T:A transversions are a mutational signature of MAP, and could be used as a biomarker in screening and identifying patients with atypical MAP, or in associating certain phenotypes with MAP. The extracolonic and extraintestinal manifestations that have been associated with MAP include duodenal adenomas, duodenal cancer, fundic gland polyps, gastric cancer, ovarian cancer, bladder cancer and skin cancer. The association of breast cancer and endometrial cancer with MAP remains disputed. Desmoids and Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPEs) are rarely reported in MAP, but have long been seen in FAP patients, and thus could act as a distinguishing feature between the two. This collection of MAP phenotypes will assist in the assessment of pathogenic MUTYH variants using the American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) Variant Interpretation Guidelines, and ultimately improve patient care.

High prevalence of MUTYH associated polyposis among minority populations in Israel, due to rare founder pathogenic variants

BACKGROUND

Autosomal recessive conditions are common in consanguineous populations. Since consanguinity is common in the Israeli Arab population, we evaluated the rate of MUTYH polyposis (MAP) among polyposis patients in this population and studied Pathogenic Variants (PVs) spectrum.

METHODS

We reviewed health records of all Arab and Druze polyposis patients referred for counseling during 2013-2020 who fulfilled the Israeli Genetic Society criteria for MUTYH/APC testing, in a tertiary center in Northern Israel and four additional gastro-genetic clinics in Israel.

RESULTS

The Northern cohort included 37 patients from 30 unrelated families; 8(26.6%) carried bi-allelic MUTYH PVs. The major variant p.Glu452del was detected in 6/8 Druze and Muslim families who shared the same haplotype. Other PVs detected in both cohorts included p.Tyr56Ter, p.His57Arg, c.849+3A>C, p.Ala357fs, and p.Tyr151Cys. Among bi-allelic carriers, 88% reported consanguinity, and 100% had positive family history for polyposis or colorectal cancer (CRC). Generally, the age of CRC was 10 years younger than reported in the general MAP population.

CONCLUSIONS

MAP accounted for 27% of polyposis cases in the Arab population of Northern Israel. PVs spectrum is unique, with high frequency of the founder variant p.Glu452del. Our results may inform the genetic testing strategy in the Israeli Arab population.

Forty-eight-year-old female MUTYH carrier presenting with five concurrent primary cancers

Background

MUTYH‐associated polyposis is a rare disorder resulting from mutations involved in DNA mismatch repair. This results in an increased susceptibility to colonic adenomatosis and other cancers. Studies have examined the resulting frequency of extracolonic manifestations; however, these typically occur alone, concurrently, or temporally separate from an already diagnosed colorectal cancer in individuals with a biallelic mutation.

Case

Reported here is a case of five distinct primary neoplasms presenting simultaneously in a patient monoallelic for an MYH mutation. These neoplasms included squamous cell carcinoma of the vulva, rectal adenocarcinoma, synchronous anal adenocarcinoma, papillary thyroid carcinoma, and ovarian serous psammocarcinoma. Throughout her course, she underwent multiple surgical procedures, neoadjuvant chemoradiation, with further adjuvant therapy, and treatment ongoing. Due to her unique presentation, she underwent genetic testing that demonstrated she was monoallelic for an MYH mutation.

Conclusion

The patient had a positive response to her treatment and surgical procedures with ongoing adjuvant therapy. She will continue to undergo further genetic testing, and testing for her children is being considered. This case demonstrates a unique presentation associated with a monoallelic MYH mutation that is not described in the current literature and warrants further investigation.

A case report of a patient with first phenotype of papillary thyroid carcinoma and heterochronous multiprimary tumor harboring germline MUTYH Arg19*/Gly286Glu mutations

MUTYH-associated polyposis (MAP) is an autosomal recessively inherited disease with multiple system tumors mainly in alimentary system. Tumor occurrence of MAP patients is highly heterogeneous in space and time. MAP is associated with germline biallelic mutations in MUTYH. The targeted next‑generation sequencing technology and Sanger sequencing are the important methods to screen MUTYH mutations now. Herein, we identified a patient with heterochronous multiprimary tumor carring MUYTH Arg19*/Gly286Glu compound heterozygous mutations. The patient in this case had a first phenotype of thyroid cancer at age 44, which earlier 2 years than the alimentary system cancers. In conclusion, our case report creases the in-depth understanding of the MAP heterogeneous phenotype and further reminds recommendations for improvement of health management and genetic counseling, special treatment plans.

<p>A Novel Mutation in <em>MYH</em> Gene Associated with Aggressive Colorectal Cancer in a Child: A Case Report and Review of Literature</p>

Colorectal cancer is a rare pediatric tumor. Pediatric patients with colorectal cancer present with more aggressive tumor biology and at later stages of the disease, higher proportions of signet ring and mucinous histology, and less differentiation. The effective treatment is same as that received by adults. The overall prognosis of pediatric colorectal cancer is generally poor. Genetic mutations have been identified as the cause of inherited cancer risk in some colorectal cancers. Here, we presented a case of a pediatric patient carrying a maternally derived, heterozygous MYH germline mutation (c.934–2A>G,intron), the mutation was not reported in pediatric patients before. Also, the patient carried somatic mutations of proto-oncogene SMAD4 (R361C) and TP53 (Y234H). The patient underwent surgical resection, chemotherapy and targeted therapy, but the prognosis was not good. We also review the literature to summarize clinical features, gene mutations, management, and outcomes of pediatric colorectal cancer patient. Our results suggest that the genetic mutation of MYH together with somatic mutations of proto-oncogene SMAD4 and TP53 may lead to the early onset colorectal cancer of the patient. Although the overall prognosis of pediatric colorectal cancer is generally poor, the pathogenesis may be related to hereditary genetic mutations as was found with the MYH gene mutation in our case. Genetic screening can provide early diagnosis and improve prognosis.

Risk of extracolonic cancers for people with biallelic and monoallelic mutations in MUTYH

Germline mutations in the DNA base excision repair gene MUTYH are known to increase a carrier's risk of colorectal cancer. However, the risks of other (extracolonic) cancers for MUTYH mutation carriers are not well defined. We identified 266 probands (91% Caucasians) with a MUTYH mutation (41 biallelic and 225 monoallelic) from the Colon Cancer Family Registry. Mutation status, sex, age and histories of cancer from their 1,903 first- and 3,255 second-degree relatives were analyzed using modified segregation analysis conditioned on the ascertainment criteria. Compared with incidences for the general population, hazard ratios (HRs) (95% confidence intervals [CIs]) for biallelic MUTYH mutation carriers were: urinary bladder cancer 19 (3.7-97) and ovarian cancer 17 (2.4-115). The HRs (95% CI) for monoallelic MUTYH mutation carriers were: gastric cancer 9.3 (6.7-13); hepatobiliary cancer 4.5 (2.7-7.5); endometrial cancer 2.1 (1.1-3.9) and breast cancer 1.4 (1.0-2.0). There was no evidence for an increased risk of cancers at the other sites examined (brain, pancreas, kidney or prostate). Based on the USA population incidences, the estimated cumulative risks (95% CI) to age 70 years for biallelic mutation carriers were: bladder cancer 25% (5-77%) for males and 8% (2-33%) for females and ovarian cancer 14% (2-65%). The cumulative risks (95% CI) for monoallelic mutation carriers were: gastric cancer 5% (4-7%) for males and 2.3% (1.7-3.3%) for females; hepatobiliary cancer 3% (2-5%) for males and 1.4% (0.8-2.3%) for females; endometrial cancer 3% (2%-6%) and breast cancer 11% (8-16%). These unbiased estimates of both relative and absolute risks of extracolonic cancers for people, mostly Caucasians, with MUTYH mutations will be important for their clinical management.

Polymorphisms in base excision repair genes and thyroid cancer risk

Thyroid cancer (TC) is the most frequent endocrine malignancy, accounting however for only 1-2% of all human cancers, and the best-established risk factor for TC is radiation exposure, particularly during childhood. Since the BER pathway seems to play an important role in the repair of DNA damage induced by IR and other genotoxicants, we carried out a hospital-based case-control study in order to evaluate the potential modifying role of 6 BER polymorphisms on the individual susceptibility to non-familial TC in 109 TC patients receiving iodine-131, and 217 controls matched for age (± 2 years), gender and ethnicity. Our results do not reveal a significant involvement of XRCC1 Arg194Trp and Arg399Gln, OGG1 Ser326Cys, APEX1 Asp148Glu, MUTYH Gln335His and PARP1 Val762Ala polymorphisms on the individual susceptibility towards TC, mostly in agreement with the limited available evidence. By histological stratification analysis, we observed that the association between the presence of heterozygosity in the MUTYH Gln335His polymorphism and TC risk almost reached significance for the papillary subtype of TC. This was the first time that the putative association between this polymorphism and TC susceptibility was evaluated. However, since the sample size was modest, the possibility of a type I error should not be excluded and this result should, therefore, be interpreted with caution. More in depth studies involving larger populations should be pursued in order to further clarify the potential usefulness of the MUTYH Gln335His genotype as a predictive biomarker of susceptibility to TC and the role of the remaining BER polymorphisms on TC susceptibility.

MUTYH-associated polyposis (MAP), the syndrome implicating base excision repair in inherited predisposition to colorectal tumors

In 2002, Al-Tassan and co-workers described for the first time a recessive form of inherited polyposis associated with germline mutations of MUTYH, a gene encoding a base excision repair (BER) protein that counteracts the DNA damage induced by the oxidative stress. MUTYH-associated polyposis (MAP) is now a well-defined cancer susceptibility syndrome, showing peculiar molecular features that characterize disease progression. However, some aspects of MAP, including diagnostic criteria, genotype-phenotype correlations, pathogenicity of variants, as well as relationships between BER and other DNA repair pathways, are still poorly understood. A deeper knowledge of the MUTYH expression pattern is likely to refine our understanding of the protein role and, finally, to improve guidances for identifying and handling MAP patients.