Lynch syndrome (LS) is a condition which predisposes individuals primarily to early-onset colorectal and endometrial cancer. LS is characterized by a germline pathogenic variant in one of the MMR ...(MisMatch Repair) gene, inducing a phenotype of microsatellite instability in the tumor, which may be associated with a loss of expression of MMR proteins detected by standard immunohistochemistry on tumor tissue. Most of the time, LS is inherited from a parent in whom the condition may not be known due to incomplete penetrance, but de novo pathogenic variant is a rare occurrence. Here, we describe the case of a 52-year-old woman with no family history of LS, referred to the genetics department for colorectal cancer at the age of 50. Genetic analysis revealed a de novo germline pathogenic variant in the
MSH6
gene. To date, this case is only the second report of a de novo pathogenic variant in the
MSH6
gene in Lynch syndrome. De novo mutations have been extensively studied over the past years, but little is known about their origin and mechanism of occurrence in MMR genes. However, knowledge of mutation status allows better cancer risk management for the patient and an appropriate genetic testing and counseling for her family.
AIM:To evaluate the risk associated with variants of the UNC5C gene recently suspected to predispose to familial colorectal cancer(CRC).METHODS:We screened patients with familial CRC forms as well as ...patients with sporadic CRCs.In a first time,we analyzed exon 11 of the UNC5C gene in 120unrelated patients with suspected hereditary CRC,58patients with suspected Lynch-associated cancer or polyposis,and 132 index cases of Lynch syndrome families with a characterized mutation in a DNA mismatch repair(MMR).Next,1023 patients with sporadic CRC and1121 healthy individuals were screened for the variants identified in patients with familial cancer.RESULTS:Of 120 patients with familial CRC of unknown etiology,one carried the previously reported mis-sense mutation p.Arg603Cys(R603C)and another exhibited the unreported variant of unknown significance p.Thr617Ile(T617I).The p.Ala628Lys(A628K)mutation previously described as the main UNC5C risk variant for familial CRC was not detected in any cases of familial CRC of unknown etiology,but was present in a patient with familial gastric cancer and in two Lynch syndrome patients in co-occurrence with MMR mutations.A statistically non-significant increase in cancer risk was identified in familial CRC and/or other Lynchassociated cancers(1/178 patients vs 2/1121 healthy controls,OR=3.2,95%CI:0.29-35.05,P=0.348)and in sporadic CRCs(4/1023 patients vs 2/1121 healthy controls,OR=2.2,95%CI:0.40-12.02,P=0.364).CONCLUSION:We confirm that UNC5C mutations are very rare in familial and sporadic CRCs,but further investigations are needed to justify routine UNC5C testing for diagnostic purposes.
Correct identification of the EGFR c.2369C>T p.(Thr790Met) variant is key to decide on a targeted therapeutic strategy for patients with acquired EGFR TKI resistance in non-small cell lung cancer. ...The aim of this study was to evaluate the correct detection of this variant in 12 tumor tissue specimens tested by 324 laboratories participating in External Quality Assessment (EQA) schemes.
Data from EQA schemes were evaluated between 2013 and 2018 from cell lines (6) and resections (6) containing the EGFR c.2369C>T p.(Thr790Met) mutation. Adequate performance was defined as the percentage of tests for which an outcome was available and correct. Additional data on the used test method were collected from the participants. Chi-squared tests on contingency tables and a biserial rank correlation were applied by IBM SPSS Statistics version 25 (IBM, Armonk, NY, USA).
In 26 of the 1190 tests (2.2%) a technical failure occurred. For the remaining 1164 results, 1008 (86.6%) were correct, 151 (12.9%) were false-negative and 5 (0.4%) included incorrect mutations. Correct p.(Thr790Met) detection improved over time and for repeated scheme participations. In-house non-next-generation sequencing (NGS) techniques performed worse (81.1%, n = 293) compared to non-NGS commercial kits (85.2%, n = 656) and NGS (97.0%, n = 239). Over time there was an increase in the users of NGS. Resection specimens performed worse (82.6%, n = 610 tests) compared to cell line material (90.9%, n = 578 tests), except for NGS (96.3%, n = 344 for resections and 98.6%, n = 312 for cell lines). Samples with multiple mutations were more difficult compared to samples with the single p.(Thr790Met) variant. A change of the test method was shown beneficial to reduce errors but introduced additional analysis failures.
A significant number of laboratories that offer p.(Thr790Met) testing did not detect this relevant mutation compared to the other EQA participants. However, correct identification of this variant is improving over time and was higher for NGS users. Revising the methodology might be useful to resolve errors, especially for resection specimens with low frequency or multiple variants. EQA providers should include challenging resections in the scheme.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A JAK2V617F‐negative polycythemia associated with low serum epo needs to be tested for an exon 12 JAK2 mutation. When negative, due to potential serious complications in PV, a next generation ...sequencing is necessary to rule out false negative results.
A JAK2V617F‐negative polycythemia associated with low serum epo needs to be tested for an exon 12 JAK2 mutation. When negative, due to potential serious complications in PV, a next generation sequencing is necessary to rule out false negative results.
Pregnancy may be complicated by a rare but life-threatening disease called thrombotic thrombocytopenic purpura (TTP). Most cases of TTP are due to an acquired autoimmune or hereditary ...(Upshaw-Schulman syndrome USS) severe deficiency of a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13 (ADAMTS13). In the present study, we performed a cross-sectional analysis of the national registry of the French Reference Center for Thrombotic Microangiopathies from 2000-2010 to identify all women who were pregnant at their initial TTP presentation. Among 592 adulthood-onset TTP patients with a severe ADAMTS13 deficiency, 42 patients with a pregnancy-onset TTP were included. Surprisingly, the proportion of USS patients (n = 10 of 42 patients 24%; confidence interval, 13%-39%) with pregnancy-onset TTP was much higher than that in adulthood-onset TTP in general (less than 5%) and was mostly related to a cluster of ADAMTS13 variants. In the present study, subsequent pregnancies in USS patients not given prophylaxis were associated with very high TTP relapse and abortion rates, whereas prophylactic plasmatherapy was beneficial for both the mother and the baby. Pregnancy-onset TTP defines a specific subgroup of patients with a strong genetic background. This study was registered at www.clinicaltrials.gov as number NCT00426686 and at the Health Authority, French Ministry of Health, as number P051064.
Abstract
Background
Congenital thrombotic thrombocytopaenic purpura (TTP) or Upshaw–Schulman syndrome (USS) is a rare, life-threatening, inherited thrombotic microangiopathy (TMA). USS is mostly due ...to bi-allelic recessive sequence variations of the
a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13
(
ADAMTS13
) gene inducing a severe ADAMTS13 deficiency (activity < 10 IU/dL). In healthy individuals, ADAMTS13 circulates in a folded conformation where CUB domains interact with the spacer domain. The spacer–CUB interaction is abrogated when ADAMTS13 is conformationally activated.
Objective
This article evaluates the influence of
ADAMTS13
sequence variations on both clinical/biological phenotype and ADAMTS13 conformation in USS.
Patients and Methods
All USS patients from the French registry for TMAs (1 January 2000 to 1 June 2017) were investigated for ADAMTS13 genotype, phenotype (activity, antigen and autoantibodies) and conformation. Clinical records were analysed (inaugural acute TTP and follow-up). Child-onset USS was compared with adult-onset USS.
Results
Fifty-six USS patients from 51 families (34 child-onset and 22 adult-onset cases) were enrolled. Child-onset USS was characterized by a large panel of
ADAMTS13
sequence variations (
n
= 43), spread all over
ADAMTS13
gene and not correlated with either clinical features or plasmatic ADAMTS13 parameters. In contrast, adult-onset USS, consisting exclusively in pregnancy-induced TTP, included a smaller and distinct panel of
ADAMTS13
sequence variations (
n
= 20) because of one mutation (p.Arg1060Trp) present in 82% of patients. ADAMTS13 conformation was studied in 16 USS patients (5 child-onset and 11 adult-onset USS, encompassing 16 distinct
ADAMTS13
sequence variations) whose ADAMTS13 antigen levels were detectable: 14 of 16 patients (87.5%) exhibited abnormalities of ADAMTS13 conformation.
Conclusion
In USS, age-onset defines two entities and
ADAMTS13
sequence variations modify ADAMTS13 conformation.
Next-generation sequencing (NGS) has enabled new approaches for detection of mutations in the BRCA1 and BRCA2 genes responsible for hereditary breast and ovarian cancer (HBOC). The search for ...germline mutations in the BRCA1 and BRCA2 genes is of importance with respect to oncogenetic and surgical (bilateral mastectomy, ovariectomy) counselling. Testing tumor material for BRCA mutations is of increasing importance for therapeutic decision making as the poly ADP ribose polymerase (PARP) inhibitor, olaparib, is now available to treat patients with specific forms of ovarian cancer and BRCA mutations. Molecular genetics laboratories should develop reliable and sensitive techniques for the complete analysis of the BRCA1 and BRCA2 genes. This is a challenge due to the size of the coding sequence of the BRCA1/2 genes, the absence of hot spot mutations, and particularly by the lower DNA quality obtained from Formalin-Fixed Paraffin-Embedded (FFPE) tissue. As a result, a number of analyses are uninterpretable and do not always provide a result to the clinician, limiting the optimal therapeutic management of patients. The availability of Fresh Frozen Tissue (FFT) for some laboratories and the excellent quality of the DNA extracted from it offers an alternative. For this reason, we evaluated Multiplicom's BRCA MASTR Dx assay on a set of 97 FFT derived DNA samples, in combination with the MID for Illumina MiSeq for BRCA1 and BRCA2 mutation detection. We obtained interpretable NGS results for all tested samples and showed > 99,7% sensitivity, specificity and accuracy.
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