A new scoring system for the diagnosis of BRCA1/2 associated breast-ovarian cancer predisposition.

International audienceCriteria have been proposed for genetic testing of breast and ovarian cancer susceptibility genes BRCA1 and BRCA2. Using simulations, this study evaluates the efficiency (sensitivity, positive predictive value [PPV] and specificity) of the various criteria used in France. The efficiency of the criteria published in 1998, which are largely used, is not optimal. We show that some extensions of these criteria provide an increase in sensitivity with a low decrease in specificity and PPV. The study shows that scoring systems (Manchester, Eisinger) have similar efficiency that may be improved. In this aim, we propose a new scoring system that takes into account unaffected individuals and kinship coefficients between family members. This system increases sensitivity without affecting PPV and specificity. Finally, we propose a two-step procedure with a large screening by the physician for recommending genetic counselling, followed by a more stringent selection by the geneticist for prescribing genetic testing. This procedure would result in an increase of genetic counselling activity but would allow the identification of almost 80% of mutation carriers among affected individuals, with a mutation detection rate of 15% and a specificity of 88%

Parent-of-origin effect in Transthyretin related amyloid polyneuropathy

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Low compliance with colonoscopic screening in first-degree relatives of patients with large adenomas.

International audienceBACKGROUND: Little is known about compliance with colonoscopy as a screening method in first-degree relatives of patients with large adenomas. Aims To evaluate the compliance with screening colonoscopy among this population, and its determinants. METHODS: Data were obtained from the family part of the GEADE study, a study on genetic factors of colorectal adenomas. Index cases were 306 patients with adenomas > or = 10 mm. All living first-degree relatives aged 40-75 who could be contacted by the index case were asked to undergo a colonoscopy, unless they had had one in the previous 5 years. RESULTS: Among 674 eligible relatives, 56 had had a colonoscopy within the preceding 5 years and 114 underwent a screening colonoscopy resulting in a compliance with screening colonoscopy of 18%. This was not related to most characteristics of index cases. Compliance was significantly lower when the index case lived in the Greater Paris area than when he/she lived in other areas (12% vs. 21%). It was higher in siblings (18%) and offspring (23%) than in parents (9%) and in relatives under 55 years old (22%) than in relatives aged 55 and over (15%). CONCLUSIONS: Compliance with colonoscopy was low in first-degree relatives of patients with large adenomas. The reasons for this should be determined and appropriate strategies developed to increase compliance

A new scoring system in cancer genetics: application to criteria for BRCA1 and BRCA2 mutation screening

Background In hereditary forms of cancer due to mutations of genes such as BRCA1 and BRCA2, methods have been proposed to predict the presence of a mutation in a family. Methods Relying on carriage probability computation is the most predictive, but scores are a good proxy and avoid using computer software. An empirical method, the Manchester scoring system, has been elaborated for BRCA1 and BRCA2 mutation identification. We propose a general scoring system based on a transformation of the carriage probability. Up to an approximation, the transformed carriage probability becomes an additive score. We applied this new scoring system to the diagnosis of BRCA1-associated and BRCA2-associated breast–ovarian cancer predisposition. Using simulations, its performance was evaluated and compared with that of the Manchester scoring system and of the exact probability. Finally, the score system was used on a sample of 4563 families screened for BRCA1 and BRCA2 mutations. Results The performance of the new scoring system was superior to the Manchester scoring system, but the probability computation remained the most predictive. The better performance of the new scoring system was attributed to accounting for unaffected family members and for the degree of kinship of relatives with the proband. Conclusions The new scoring system has a theoretical basis and may be applied to any cancer family syndrome and, more generally, to any disease with monogenic subentities, in which the causal gene mutations have been identified. It will be easily modified when additional predictive factors are found

Colonoscopic screening of first-degree relatives of patients with large adenomas: increased risk of colorectal tumors.: Adenomas in relatives and colorectal tumor risk

International audienceBackground & Aims: The risk of developing colorectal neoplasia is not well established among family members of individuals with large adenomas and screening strategies remain under debate in this population. This study aimed at quantifying the risk of colorectal adenomas and cancers using colonoscopic screening in first-degree relatives of patients with large adenomas. Methods: This case-control study was performed in 18 endoscopic units of French non-University Hospitals. A colonoscopy was offered to first-degree relatives of 306 index cases with adenomas ≥ 10 mm, if they were alive, aged 40-75 and could be contacted by the index case. Among 674 relatives meeting these criteria, 168 were examined and matched for age, gender, and geographical area with two controls (n=307). Controls were randomly selected from 1362 consecutive patients aged 40-75 having undergone a colonoscopy for minor symptoms. Results: The overall prevalence of large adenomas was 8.4% and 4.2% in relatives and controls, respectively. Odds ratios (OR) associated with a history of large adenomas in relatives were 2.27 (95% confidence interval [CI]: 1.01-5.09) for cancers or large adenomas and 1.21 (95% CI: 0.68-2.15) for small adenomas, and 1.56 (95% CI: 0.96-2.53) for all colorectal neoplasia. The risk of large adenomas and cancers was higher in relatives of index cases younger than 60 years (OR: 3.82; 95% CI: 0.92-15.87) and when the index case had large distal adenomas (OR, 3.14; 95% CI: 1.27-7.73). Conclusion: First-degree relatives of patients with large adenomas are at increased risk of developing colorectal cancers or large adenomas. This result has implications for screening in this high-risk population

TTR familial amyloid polyneuropathy: does a mitochondrial polymorphism entirely explain the parent-of-origin difference in penetrance?

The Val30Met transthyretin familial amyloid polyneuropathy (TTR-V30M-FAP) is the most frequent familial amyloidosis, with autosomal dominant transmission. This severe disease shows important differences in age of onset and penetrance. Recently, a difference in penetrance according to the gender of the transmitting parent was elicited in different geographic areas with a higher penetrance in case of maternal transmission of the trait. In addition, differences in mitochondrial haplogroup distribution in early and late onset Swedish and French cases of TTR-V30M-FAP suggested that a polymorphism of mitochondrial DNA could be one underlying mechanism of the phenotypic variation. We further investigated this hypothesis by modeling the penetrance function with a parent-of-origin and/or a mitochondrial polymorphism effect in samples of Portuguese (n=33) and Swedish families (n=86) with TTR-V30M-FAP in which several individuals had been tested for mitochondrial haplogroups. Our analysis showed that a mitochondrial polymorphism effect was sufficient to explain the observed difference in penetrance according to gender of the transmitting parent in the Portuguese sample, whereas, in the Swedish sample, a clear residual parent-of-origin effect remained. This study further supported the role of a mitochondrial polymorphism effect that might induce a higher penetrance in case of maternal inheritance of the disease. In clinical practice, these results might help to better delineate the individual disease risk and have a significant impact on the management of both patients and carriers

Cancer risks associated with germline mutations in MLH1, MSH2, and MSH6 genes in Lynch syndrome.

International audienceCONTEXT: Providing accurate estimates of cancer risks is a major challenge in the clinical management of Lynch syndrome. OBJECTIVE: To estimate the age-specific cumulative risks of developing various tumors using a large series of families with mutations of the MLH1, MSH2, and MSH6 genes. DESIGN, SETTING, AND PARTICIPANTS: Families with Lynch syndrome enrolled between January 1, 2006, and December 31, 2009, from 40 French cancer genetics clinics participating in the ERISCAM (Estimation des Risques de Cancer chez les porteurs de mutation des gènes MMR) study; 537 families with segregating mutated genes (248 with MLH1; 256 with MSH2; and 33 with MSH6) were analyzed. MAIN OUTCOME MEASURE: Age-specific cumulative cancer risks estimated using the genotype restricted likelihood (GRL) method accounting for ascertainment bias. RESULTS: Significant differences in estimated cumulative cancer risk were found between the 3 mutated genes (P = .01). The estimated cumulative risks of colorectal cancer by age 70 years were 41% (95% confidence intervals [CI], 25%-70%) for MLH1 mutation carriers, 48% (95% CI, 30%-77%) for MSH2, and 12% (95% CI, 8%-22%) for MSH6. For endometrial cancer, corresponding risks were 54% (95% CI, 20%-80%), 21% (95% CI, 8%-77%), and 16% (95% CI, 8%-32%). For ovarian cancer, they were 20% (95% CI, 1%-65%), 24% (95% CI, 3%-52%), and 1% (95% CI, 0%-3%). The estimated cumulative risks by age 40 years did not exceed 2% (95% CI, 0%-7%) for endometrial cancer nor 1% (95% CI, 0%-3%) for ovarian cancer, irrespective of the gene. The estimated lifetime risks for other tumor types did not exceed 3% with any of the gene mutations. CONCLUSIONS: MSH6 mutations are associated with markedly lower cancer risks than MLH1 or MSH2 mutations. Lifetime ovarian and endometrial cancer risks associated with MLH1 or MSH2 mutations were high but do not increase appreciably until after the age of 40 years