[Heredity and cancer]. / Hérédité et cancer.

A personal or family history of cancer has now become the primary cause of genetic consultations. In recent years, various genes have been identified that are associated with a more or less marked genetic predisposition to the development of cancers. The syndrome associated with the hereditary risk of breast and ovarian cancer and the Lynch syndrome are the most frequent ones, but there are many other, much less common, situations associated with familial cancer risk. In most cases, there are clear recommendations regarding the indications for genetic testing and the follow-up of patients identified as having a predisposition to cancer. At the CHU of Liège, we currently perform more than 1.400 oncogenetic consultations per year and we maintain a positivity rate of genetic tests performed in this indication higher than 10%. In this way, we allow a multidisciplinary care of patients with a high oncological risk and participate in a prevention and surveillance activity. We also pay increasing attention to the hereditary risk associated with pediatric cancers and to patients with multiple cancers, especially when these develop at an early age. Finally, the oncogenetic consultation must consider the psychological, ethical and legal aspects of a diagnosis that involves the patient and his or her future, but also the whole family.

Une histoire personnelle ou familiale de cancer est aujourd'hui devenue la première cause de consultation en génétique. Au cours de ces dernières années, en effet, différents gènes associés à une prédisposition génétique plus ou moins marquée au développement de pathologies cancéreuses ont été identifiés. Le syndrome de prédisposition héréditaire au cancer du sein et de l'ovaire (HBOC : Hereditary Breast and/or Ovarian Cancer) et le syndrome de Lynch sont les plus fréquents. Mais il existe une multitude d'autres situations beaucoup moins fréquentes associées à un risque familial de cancer. Dans la plupart des cas, des recommandations claires existent quant à l'indication des tests génétiques et quant au suivi proposé au patient chez qui une prédisposition au cancer est identifiée. Au CHU de Liège, nous réalisons actuellement plus de 1.400 consultations d'oncogénétique par an et nous maintenons un taux de positivité des tests génétiques réalisés dans cette indication supérieur à 10 %. De cette façon, nous permettons une prise en charge multidisciplinaire des patients avec un haut risque oncologique et participons à une activité de prévention et de surveillance. Nous portons une attention croissante aux enfants et adolescents présentant un cancer, d'une part, et aux adultes ayant présenté de multiples cancers, d'autre part, particulièrement lorsque ceux-ci se développent à un âge précoce. Enfin, la consultation d'oncogénétique doit tenir compte des aspects psychologiques, éthiques et légaux, liés à un diagnostic qui implique le patient et son avenir, mais également l'ensemble de la famille.

Genome-Wide Association Study of Acute Renal Graft Rejection.

Acute renal rejection is a major risk factor for chronic allograft dysfunction and long-term graft loss. We performed a genome-wide association study to detect loci associated with biopsy-proven acute T cell-mediated rejection occurring in the first year after renal transplantation. In a discovery cohort of 4127 European renal allograft recipients transplanted in eight European centers, we used a DNA pooling approach to compare 275 cases and 503 controls. In an independent replication cohort of 2765 patients transplanted in two European countries, we identified 313 cases and 531 controls, in whom we genotyped individually the most significant single nucleotide polymorphisms (SNPs) from the discovery cohort. In the discovery cohort, we found five candidate loci tagged by a number of contiguous SNPs (more than five) that was never reached in iterative in silico permutations of our experimental data. In the replication cohort, two loci remained significantly associated with acute rejection in both univariate and multivariate analysis. One locus encompasses PTPRO, coding for a receptor-type tyrosine kinase essential for B cell receptor signaling. The other locus involves ciliary gene CCDC67, in line with the emerging concept of a shared building design between the immune synapse and the primary cilium.

Association of neurexin 3 polymorphisms with smoking behavior.

The Neurexin 3 gene (NRXN3) has been associated with dependence on various addictive substances, as well as with the degree of smoking in schizophrenic patients and impulsivity among tobacco abusers. To further evaluate the role of NRXN3 in nicotine addiction, we analyzed single nucleotide polymorphisms (SNPs) and a copy number variant (CNV) within the NRXN3 genomic region. An initial study was carried out on 157 smokers and 595 controls, all of Spanish Caucasian origin. Nicotine dependence was assessed using the Fagerström index and the number of cigarettes smoked per day. The 45 NRXN3 SNPs genotyped included all the SNPs previously associated with disease, and a previously described deletion within NRXN3. This analysis was replicated in 276 additional independent smokers and 568 controls. Case-control association analyses were performed at the allele, genotype and haplotype levels. Allelic and genotypic association tests showed that three NRXN3 SNPs were associated with a lower risk of being a smoker. The haplotype analysis showed that one block of 16 Kb, consisting of two of the significant SNPs (rs221473 and rs221497), was also associated with lower risk of being a smoker in both the discovery and the replication cohorts, reaching a higher level of significance when the whole sample was considered [odds ratio = 0.57 (0.42-0.77), permuted P = 0.0075]. By contrast, the NRXN3 CNV was not associated with smoking behavior. Taken together, our results confirm a role for NRXN3 in susceptibility to smoking behavior, and strongly implicate this gene in genetic vulnerability to addictive behaviors.