BACKGROUND:McCune-Albright syndrome MAS is a rare mosaic disorder caused by post-zygotic GNAS activating mutations. MAS is characterized by fibrous dysplasia (FD) of the skeleton, café-au-lait skin macules, and hyperfunctioning endocrinopathies such as precocious puberty, thyroid disease, growth hormone excess, and FGF23-mediated phosphate wasting. Mosaicism leads to marked clinical heterogeneity and complicates molecular diagnosis. METHODS:We retrospectively analyzed clinical and genotyping data of patients referred for suspected or clinically diagnosed MAS in a single French center (2014-2025). GNAS R201C and R201H mutations were detected by digital droplet PCR using peripheral blood as first-line samples, with additional testing of circulating cell-free, saliva, or tissue when indicated. RESULTS:We included 405 patients, from which 89 (22%) carried a GNAS mutation (52 R201C, 37 R201H). No significant clinical differences were observed between R201C and R201H. Among 578 analyzed samples, mutation detection varied by sample type, with the highest rates in tissue. Mutant allele frequency (MAF) in blood DNA was higher in patients with polyostotic than in monostotic FD (P=0.0055), but was not associated with the overall MAS-related lesion number. No correlation was found between MAF and age at diagnosis. CONCLUSIONS:MAS shows substantial clinical and molecular heterogeneity without clear genotype-phenotype differences between R201 variants. Mutation detection strongly depends on sample type, reflecting disease mosaicism. A multimodal diagnostic strategy and larger collaborative cohorts are needed to optimize molecular diagnosis and refine genotype-phenotype correlations in MAS patients.

We describe for the first time the case of a woman presenting with Tatton-Brown-Rahman syndrome (TBRS) and multiple endocrine neoplasia (MEN). She developed primary hyperparathyroidism at age 13, a pituitary cyst at age 14, adrenal tumor at age 21, and metastatic insulinoma at age 34. In addition, she showed intellectual disability, obesity, multiple lipomas, facial dysmorphia, hemihypertrophy and kyphoscoliosis. At age 35, genome analysis revealed a pathogenic de-novo heterozygous germline DNMT3A variant, while classic MEN syndromes were ruled out by targeted somatic and germline genetic testing. This case highlights not only the importance of genomic analysis in patients with multiple and atypical conditions, but also the need for a multidisciplinary approach for TBRS patients, including in adulthood, involving endocrinologists to enhance understanding and optimize monitoring of this syndrome.

MEN1 loss of heterozygosity in meningiomas of patients #8, #15 and #16. Electropherogram of Sanger sequencing on tumor DNA showing falsely homozygous MEN1 pathogenic variants due to loss of heterozygosity at a somatic level. Patient #8: c.1037_1038delCT, p.(Thr346SerfsTer20), patient #15: c.249_252delGTCT, p.(Ile85SerfsTer33), patient #16: c.515A>T, p.(Asp172Val)

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Sporadic meningothelial meningiomas characteristics

Sporadic ependymomas characteristics

AbstractPurpose: Multiple endocrine neoplasia type 1 (MEN1) is thought to increase the risk of meningioma and ependymoma. Thus, we aimed to describe the frequency, incidence, and specific clinical and histological features of central nervous system (CNS) tumors in the MEN1 population (except pituitary tumors). Experimental Design: The study population included patients harboring CNS tumors diagnosed with MEN1 syndrome after 1990 and followed up in the French MEN1 national cohort. The standardized incidence ratio (SIR) was calculated based on the French Gironde CNS Tumor Registry. Genomic analyses were performed on somatic DNA from seven CNS tumors, including meningiomas and ependymomas from patients with MEN1, and then on 50 sporadic meningiomas and ependymomas. Results: A total of 29 CNS tumors were found among the 1,498 symptomatic patients (2%; incidence = 47.4/100,000 person-years; SIR = 4.5), including 12 meningiomas (0.8%; incidence = 16.2/100,000; SIR = 2.5), 8 ependymomas (0.5%; incidence = 10.8/100,000; SIR = 17.6), 5 astrocytomas (0.3%; incidence = 6.7/100,000; SIR = 5.8), and 4 schwannomas (0.3%; incidence = 5.4/100,000; SIR = 12.7). Meningiomas in patients with MEN1 were benign, mostly meningothelial, with 11 years earlier onset compared with the sporadic population and an F/M ratio of 1/1. Spinal and cranial ependymomas were mostly classified as World Health Organization grade 2. A biallelic MEN1 inactivation was observed in 4/5 ependymomas and 1/2 meningiomas from patients with MEN1, whereas MEN1 deletion in one allele was present in 3/41 and 0/9 sporadic meningiomas and ependymomas, respectively. Conclusions: The incidence of each CNS tumor was higher in the MEN1 population than in the French general population. Meningiomas and ependymomas should be considered part of the MEN1 syndrome, but somatic molecular data are missing to conclude for astrocytomas and schwannomas.

e13535 Background: GB are highly aggressive tumors which systematically relapse. Our objective was to identify disease progression mechanisms and genomic drivers of GB treatment resistance. Methods: Ten paired frozen tumors from initial and recurrent surgery after RTCT were screened by CGH Array. Next, NGS of the selected genes was performed on 19 paired tumors (38 samples). Molecular alterations were correlated with patient data. TCGA was used to characterize the molecular profile of MPDZ. Results: Nineteen IDHwt GB patients with a median age of 54.5 years (37.2-72.8) were included. Using CGH array, unsupervised analysis clustered the whole samples by paired of initial and recurrent tumors. However only 44% of CGH Array alterations were shared between initial and recurrent tumors (amplifications: 55%; deletions: 30%). The new alterations detected at relapse were amplifications in 25% and deletions in 23% of tumors. Two regions corresponding to 171 genes were lost at relapse (p = 0.03): 19q13.33 and 19q13.41. Using DAVID genome, 3/171 genes (related to neutrophil chemotactic factors) were identified: FPR1, FPR2, FPR3. Moreover, 24 genes were lost (including MPDZ) and 2 genes were gained in 20% of recurrent tumors. Totally, 29 genes were analyzed by NGS and 4 genes showed pathogenic mutations shared by initial and recurrent tumors: FPR2, REL, TYRP1 and MPDZ. Only MPDZ showed, at relapse, an increasing rate of mutated variants and a new mutation affecting the splicing site. These alterations were independent from classical prognostic factors (age, sexe, karnofsky performans status, MMS and MGMT status) and from patient survivals. To explore MPDZ expression, we used TCGA initial dataset and observed that a lower RNA expression of MPDZ was associated with IDHwt ( p< 0.001) and grade IV ( p< 0.001) gliomas, reinforcing the potential pejorative impact of MPDZ loss. Conclusions: Our results suggest that MPDZ is frequently altered at initial diagnosis with increased alterations in recurrent IDHwt GB after RTCT, suggesting that MPDZ impairment could contribute to the resistance/relapse mechanisms. Further investigations are needed to validate these results.

MEN1 is an autosomal dominant hereditary syndrome characterized by several endocrine tumors, in most cases affecting the parathyroid glands, pancreas, and anterior pituitary. It is the result of inactivating mutations in the tumor suppressor gene MEN1. More than 1300 different mutations have been identified in this gene. Mosaic MEN1 mutations have been previously described in only a few patients in the literature. In this paper, we provide a review of six cases of MEN1 mosaicism reported in the literature supplemented with six additional cases described by the French TENgen network of laboratories. This review highlights that (i) MEN1 mosaicism is not associated with a mild phenotype and results in the same natural history as heterozygous MEN1 mutation and (ii) that more systematic detection of MEN1 mosaic mutation enables improvements in both patient monitoring and genetic counseling.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Purpose Mosaicism is a feature of several inherited tumor syndromes. Only a few cases of mosaicism have been described in multiple endocrine neoplasia type 1 (MEN1). Next-generation sequencing (NGS) offers new possibilities for detecting mosaicism. Here, we report the first study to systematically look for MEN1 mosaicism, using blood DNA, in MEN1-suspected patients but without MEN1 pathogenic variants (PV) in a heterozygous state. Methods Digital targeted NGS, including unique molecular identifiers (UMIs), was performed in routine practice, and the analytic performance of this method was verified. Results Among a cohort of 119 patients harboring from 2 to 5 MEN1 lesions, we identified 3 patients with MEN1 mosaic PVs. The allele frequencies ranged from 2.3 to 9.5%. The detection rate of MEN1 mosaicism in patients bearing at least 3 MEN1 lesions was 17% (3/18). No cases were detected in patients with two lesions. Conclusion We report here three new cases with MEN1 mosaicism. This study examined the performance of UMI in the diagnosis of MEN1 mosaicism in routine practice, and our results underline that the frequency of mosaicism is probably underestimated in patients with suspected MEN1.

CONTEXT:Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease caused by inactivating mutations in the MEN1 gene. In the literature, few cases of MEN1 have been reported because of mosaic MEN1 mutations.OBJECTIVE:We performed an extensive molecular characterization in several lesions and blood samples, including plasmatic circulating cell-free DNA (ccfDNA) in an exceptional case of a patient with MEN1 mosaicism causing primary hyperparathyroidism, multiple pancreatic neuroendocrine tumors (NETs), and a metastatic thymic NET.METHODS:Blood, ccfDNA and multiple tissue analysis were performed by next-generation sequencing.RESULTS:MEN1 mosaicism was confirmed by multiple tissue analysis. Somatic analysis of the largest pancreatic NET revealed the same MEN1 second-hit mutation as found in the thymic lesion, demonstrating its metastatic origin from the thymic lesion. Moreover, in ccfDNA we found the mosaic MEN1 mutation but also the somatic second-hit mutation found in the thymic primary tumor, revealing the presence of circulating tumor DNA (ctDNA). After surgical removal of the pancreatic metastasis, the mutated fraction of both mutations decreased, before increasing again several weeks before a new clinical relapse, suggesting that thymic ctDNA may be used as an early tumor biomarker.CONCLUSION:This exceptional MEN1 case highlighted (1) the importance of looking for MEN1 mosaicism, (2) that MEN1 mosaicism can cause very aggressive disease, and (3) the interest in analyzing ccfDNA for confirming MEN1 mosaicism but also as a potential tumor biomarker for NET.

L’identification d’une mutation de MEN1 en mosaïque dans le sang permet d’expliquer certains tableaux cliniques d’authentique NEM1 sans mutation identifiée. Néanmoins pour écarter un faux-positif dû à une hématopoïèse clonale, il est préférable de confirmer la mutation sur un prélèvement d’une autre nature. Nous rapportons ici le cas d’un patient présentant à l’âge de 43 ans un carcinome neuroendocrine thymique bien différencié et une hyperparathyroïdie primaire sur une hyperplasie multiglandulaire faisant suspecter une NEM1. Malgré un traitement chirurgical et par chimiothérapie, la tumeur thymique progresse avec des métastases ganglionnaires et osseuses. En 2019 (53 ans), aucune mutation ni délétion hétérozygote de MEN1 n’est identifiée au niveau germinal. Nous découvrons une mutation en mosaïque dans le sang total (c.496=/C>T) à une fréquence de 9,5 %. Nous confirmons cette mutation sur l’ADN somatique de deux lésions du patient : dans une parathyroïde avec une perte d’hétérozygotie, et dans le thymus à l’état hétérozygote avec un second hit mutationnel hétérozygote (c.784-9G>A), mais également dans l’ADN libre circulant plasmatique (ADNlc), libéré par lyse des cellules somatiques. Dans l’ADNlc, cette mutation présente une fréquence plus élevée que dans le sang total, à 16 %, et on retrouve également la seconde mutation thymique à une fréquence de 6,5 %, signe que l’augmentation de la fraction mutée est due à la présence d’ADN circulant tumoral (ADNct) d’origine thymique. Ce cas exceptionnel suggère : (1) l’intérêt d’analyser l’ADNlc en cas de mosaïcisme pour confirmer le diagnostic moléculaire ; (2) un potentiel intérêt de l’étude l’ADNct dans le suivi des tumeurs thymiques.

Xeroderma Pigmentosum (XP) is a rare genetic disorder affecting the nucleotide excision repair system (NER). It is characterized by an extreme sensitivity to sunlight that induces cutaneous disorders such as severe sunburn, freckling and cancers. In Tunisia, six complementation groups have been already identified. However, the genetic etiology remains unknown for several patients. In this study, we investigated clinical characteristics and genetic defects in two families with atypical phenotypes originating from the central region in Tunisia. Clinical investigation revealed mild cutaneous features in two patients who develop multiple skin cancers at later ages, with no neurological disorders. Targeted gene sequencing revealed that they carried novel variants. A homozygous variation in the ERCC4 gene c.1762G>T, p.V588F, detected in patient XP21. As for patient XP134, he carried two homozygous mutations in the DDB2 gene c.613T>C, p.C205R and c.618C>A, p.S206R. Structural modeling of the protein predicted the identified ERCC4 variant to mildly affect protein stability without affecting its functional domains. As for the case of DDB2 double mutant, the second variation seems to cause a mild effect on the protein structure unlike the first variation which does not seem to have an effect on it. This study contributes to further characterize the mutation spectrum of XP in Tunisian families. Targeted gene sequencing accelerated the identification of rare unexpected genetic defects for diagnostic testing and genetic counseling.

Dix pour cents des cas index de Néoplasie Endocrinienne Multiple de type 1 sont dues à des mutations du gène MEN1 dites de novo, c’est-à-dire, présentes chez l’individu mais absentes du patrimoine génétique de ses parents1. Nous avons repris tous les cas de mutations de MEN1 a priori de novo recensés au laboratoire depuis 2006. Nous avons ainsi sélectionné 9 cas index avec l’ADN de leurs parents. L’ADN des parents a été analysé par technique de séquençage à haut débit permettant de détecter les mutations de faible fréquence allélique, le digital NGS. Parmi les 9 familles NEM1 analysées, la mutation de l’enfant a été retrouvée chez l’un des 2 parents à l’état de mosaïque dans 2 familles. Dans ces 2 cas, le parent était porteur d’au moins une lésion du spectre de la NEM1. Pour l’un des cas, le parent avait développé des lésions avant que le diagnostic ne soit porté chez son enfant. Dans les 7 autres cas, la mutation de l’enfant n’a pas été retrouvée chez les 2 parents avec une sensibilité inférieure à 1 %. Ces parents étaient totalement asymptomatiques. En conclusion : (1) Les mutations en mosaïque du gène MEN1 sont probablement sous-estimées car non recherchées systématiquement ; (2) Un parent symptomatique d’un enfant porteur d’une mutation apparemment de novo doit être considéré comme porteur de la mutation à l’état de mosaïque, même en l’absence de preuve moléculaire et doit en conséquence bénéficier d’un suivi de NEM1 et d’un conseil génétique adapté au risque de récurrence.

BACKGROUND:The '3PAs' syndrome, associating pituitary adenoma (PA) and pheochromocytoma/paraganglioma (PPGL), is sometimes associated with mutations in PPGL-predisposing genes, such as SDHx or MAX. In '3PAs' syndrome, PAs can occur before PPGL, suggesting a new gateway into SDHx/MAX-related diseases.OBJECTIVE:To determine the SDHx/MAX mutation prevalence in patients with isolated PAs and characterize PAs of patients with SDHx/MAX mutations.DESIGN:Genes involved in PAs (AIP/MEN1/CDKN1B) or PPGLs (SDHx/MAX) were sequenced in patients with isolated PAs. We then conducted a review of cases of PA in the setting of '3PAs' syndrome.RESULTS:A total of 263 patients were recruited. Seven (likely) pathogenic variants were found in AIP, two in MEN1, two in SDHA, and one in SDHC. The prevalence of SDHx mutations reached 1.1% (3/263). Of 31 reported patients with PAs harboring SDHx/MAX mutations (28 published cases and 3 cases reported here), 6/31 (19%) developed PA before PPGL and 8/31 (26%) had isolated PA. The age of onset was later than in patients with AIP/MEN1 mutations. PAs were mainly macroprolactinomas and showed intracytoplasmic vacuoles seen on histopathology.CONCLUSIONS:We discovered SDHx mutations in patients bearing PA who had no familial or personal history of PPGL. However, the question of incidental association remains unresolved and data to determine the benefit of SDHx/MAX screening in these patients are lacking. We recommend that patients with isolated PA should be carefully examined for a family history of PPGLs. A family history of PPGL, as well as the presence of intracytoplasmic vacuoles in PA, requires SDHx/MAX genetic testing of patients.

Molecular diagnosis of rare inherited palmoplantar keratoderma (PPK) is still challenging. We investigated at the clinical and genetic level a consanguineous Tunisian family presenting an autosomal dominant atypical form of transgrediens and progrediens PPK to better characterize this ultrarare disease and to identify its molecular etiology. Whole-exome sequencing (WES), filtering strategies, and bioinformatics analysis have been achieved. Clinical investigation and follow up over 13 years of this Tunisian family with three siblings formerly diagnosed as an autosomal recessive form of Mal de Melela-like conducted us to reconsider its initial phenotype. Indeed, the three patients presented clinical features that overlap both Mal de Meleda and progressive symmetric erythrokeratoderma (PSEK). The mode of inheritance was also reconsidered, since the mother, initially classified as unaffected, exhibited a similar expression of the disease. WES analysis showed the absence of potentially functional rare variants in known PPKs or PSEK-related genes. Results revealed a novel heterozygous nonsynonymous variant in cadherin-12 gene ( CDH12 , NM_004061, c.1655C > A, p.Thr552Asn) in all affected family members. This variant is absent in dbSNP and in 50 in-house control exomes. In addition, in silico analysis of the mutated 3D domain structure predicted that this variant would result in cadherin-12 protein destabilization and thermal instability. Functional annotation and biological network construction data provide further supporting evidence for the potential role of CDH12 in the maintenance of skin integrity. Taken together, these results suggest that CDH12 gene is a potential candidate gene for an atypical presentation of an autosomal dominant form of transgrediens and progrediens PPK.

Le syndrome “3PAs” associe adénome hypophysaire (AH) et phéochromocytome/paragangliome (PPGL) et peut être associé à des mutations germinales des gènes SDHx (SDHA/SDHB/SDHC/SDHD/SDHAF2). Parfois, l’AH peut survenir avant le PPGL, suggérant une nouvelle porte d’entrée dans les pathologies liées aux SDHx. Notre objectif est de déterminer la prévalence des mutations SDHx dans un contexte d’AH isolé, et de caractériser les AH associés à des mutations SDHx par une revue de la littérature. Nous avons analysé par NGS les gènes SDHx et MEN1/AIP/CDKN1B chez 263 patients porteurs d’un AH isolé. Trois patients portaient un variant probablement pathogène (2 SDHA, 1 SDHC), soit 1,1 % (3/263). En plus de nos 3 patients, 28 patients présentaient un AH et une mutation de SDHx dans la littérature. Sur ces 31 patients, 6 (19 %) ont développés l’AH avant le PPGL et 8 (26 %) présentaient un AH isolé. Ils s’agissaient principalement de macroprolactinome, présentant parfois des vacuoles intracytoplasmiques en histologie. L’âge de survenue de l’AH est supérieur à celui des patients présentant une mutation de MEN1 ou AIP. En conclusion, nous avons retrouvé des mutations SDHx chez des patients présentant un AH sans antécédents de PPGL. Néanmoins, le lien de causalité entre les deux n’est pas formel et le bénéfice d’un dépistage génétique de SDHx dans le contexte d’un AH isolé n’est pas encore établi. Nous soulignons l’importance de rechercher des antécédents personnels ou familiaux de PPGLs chez les patients porteurs d’AH, afin de proposer un dépistage SDHx.