Academic literature on the topic 'Congenital hypogonadotropic hypogonadism'

Congenital hypogonadotropic hypogonadism (CHH) is characterized by complete or partial failure of pubertal development because of inadequate secretion of gonadotropic hormones. CHH consists of hypogonadotropic hypogonadism with anosmia or hyposmia, Kallmann syndrome, and the normosmic variation normosmic idiopathic hypogonadotropic hypogonadism. CHH is one of the few treatable diseases of male infertility, although men with primary testicular dysfunction have irreversibly diminished spermatogenic capacity. The approach to CHH treatment is determined by goals such as developing virilization or inducing fertility. This review focuses on the current knowledge of therapeutic modalities for inducing puberty and fertility in men with CHH.

Congenital isolated hypogonadotropic hypogonadism includes a group of diseases related to the defects of secretion and action of gonadotropin-releasing hormone (GNRH) and gonadotropins. In a half of cases congenital hypogonadism is associated with an impaired sense of smell. It’s named Kallmann syndrome. Now 40 genes are known to be associated with function of hypothalamus pituitary gland and gonads. Phenotypic features of hypogonadism and therapy effectiveness are related to different molecular defects. However clinical signs may vary even within the same family with the same molecular genetic defect. Genotype phenotype correlation in patients with congenital malformations prioritizes the search for mutations in candidate genes. There are data of significant contribution of oligogenicity into the phenotype of the disease are presented in the review. Moreover, an issue of current isolated hypogonadotropic hypogonadism definition and classification revision is raised in the review due to hypogonadotropic hypogonadism development while there are mutations in genes not associated with GNRH neurons secretion and function.

BACKGROUND: Gonadotropin therapy in boys with congenital isolated hypogonadotropic hypogonadism helps to increase testes volume and induce spermatogenesis in comparison with testosterone therapy. However, difficulties with dose titration, partial therapy success, absence of generally accepted regimen protocols don’t allow to use this therapy in order to induce puberty in adolescents with Kallmann syndrome or normosmic hypogonadotropic hypogonadism.AIM: To assess the effectiveness of combination hormonal replacement therapy via human chorionic gonadotropin and recombinant follicle stimulation hormone in adolescents with congenital isolated normosmic hypogonadotropic hypogonadism and with Kallmann syndromeMATERIALS AND METHODS: This is an open single-center prospective non-controlled study. Boys with hypogonadotropic hypogonadism were receiving hormonal replacement therapy for 12 months. Initial dose of human chorionic gonadotropin was 500 IU per week. Initial dose of recombinant follicle stimulation hormone was 37.5 IU per week. Doses were doubled in 6 months. Antropometric data, Tanner stage, testes volumes, inhibin B and anti-Mullerian hormone (AMH) levels were evaluated in all the patients before the treatment, after 6 and 12 months of the therapy.RESULTS: 8 boys with hypogonadotropic hypogonadism were included into the study. Median age before therapy initiation was 15.7 years [15.33; 16.41]. In 12 months after the therapy initiation puberty development, testosterone increase from 0.44 [0.34;0.62] to 4.39 [0.88;10.51] nmol/l (p=0.012), AMH decrease from 35.70 [18.00;59.00] to 14.41 [11.60;16.65] ng/ml were noted in all the patients (p=0.017). Testes volumes increase and inhibin B level increase were not statistically significant.CONCLUSION: Gonadotropin therapy is effective in order to puberty initiation in adolescents with congenital hypogonadotropic hypogonadism. In helps to achieve not only androgenization, but also to Sertoli cells maturation.

Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder characterised by lack of pubertal development and infertility, due to deficient production, secretion or action of gonadotropin-releasing hormone (GnRH). Clinically, there are variants of CHH with hypo-/anosmia (Kalman syndrome) and normosmic hypogonadotropic hypogonadism. Given a growing list of gene mutations accounting for CHH, the application of next generation sequencing (NGS) comprises an excellent molecular diagnostic approach because it enables the simultaneous evaluation of many genes. Biallelic mutations in GNRHR gene lead to the development of hypogonadotropic hypogonadism with normosmia. In this paper, we describe 16 patients with proven GnRH resistance and estimate the frequency of pathogenic variants in the GNRHR gene in the Russian population.

L’ipogonadismo ipogonadotropo congenito (CHH) è una malattia rara ed eterogenea con una importante componente genetica. Sono descritte tutte le forme di ereditarietà possibili, sia autosomica che X-linked. Dal punto di vista clinico i soggetti con CHH presentano sia delle alterazioni a carico del sistema riproduttivo ma anche dei fenotipi non riproduttivi. Dal punto di vista riproduttivo possiamo avere tratti quali il criptorchidismo e/o il micropene e/o l’ipospadia nei maschi già in epoca neonatale, oppure, in entrambi i sessi, uno sviluppo puberale assente o parziale in epoca adolescenziale e infertilità in età adulta. Per quanto riguarda i fenotipi non riproduttivi, quello più caratteristico è rappresentato dai difetti olfattivi, quali ipo- o anosmia. L’associazione di difetto olfattivo e CHH viene identificato come sindrome di Kallmann (KS), mentre le forme di CHH senza difetti olfattivi sono denominate CHH normosmico (nCHH). Altri fenotipi non riproduttivi associati possono essere la presenza di sincinesie bimanuali, difetti della linea mediana (come labio e/o palatoschisi), difetti renali (agenesia o disgenesia), difetti uditivi (sordità neurosensoriale), difetti dentali (agenesia dentale), daltonismo, nistagmo. A causa della ridotta/assente fertilità spontanea di questi soggetti, prevalgono i casi sporadici rispetto ai casi famigliari anche se il progressivo perfezionamento delle tecniche di procreazione medicalmente assistita sta sempre più cambiando questa realtà. Proprio grazie alla presenza dei casi famigliari, agli studi su modelli animali e alle tecnologie di sequenziamento di nuova generazione siamo oggi in grado di associare 25 geni candidati alle forme di CHH. Va tuttavia segnalato che l’espressività e/o la penetranza di questi difetti genetici è estremamente variabile. Questo è in parte giustificato dall’evidenza che questa malattia non sia di fatto monogenica, come si pensava inizialmente, ma invece oligogenica. D’altro canto però, è anche possibile che vi siano meccanismi genetici e/o epigenetici aggiuntivi che restano ancora da descrivere. Con lo scopo di comprendere meglio la componente genetica del CHH, nella prima parte del lavoro presentato in questa tesi e` stato condotto uno screening genetico dei principali geni coinvolti in CHH sulla più grande coorte di pazienti italiani (n=512). Questa operazione ha permesso l'identificazione di un totale di 204 varianti nel 32,2% dei casi clinici esaminati. L'analisi delle varianti ha evidenziato una componente oligogenica nel 4,6% dei pazienti. Tra i geni più frequentemente coinvolti nella nostra coorte un ruolo sicuramente importante è quello del gene PROKR2 che presenta varianti nel 7,5% dei casi. Lo screening genetico ha infatti permesso di individuare ben 17 varianti alleliche in questo gene di cui quattro mai state descritte in letteratura (p.G70S, p.D99N, p.C208S, p.M278K). PROKR2 è un gene noto per avere un ruolo importante, benchè non pienamente compreso, durante il processo di migrazione dei neuroni GnRH. E’ noto che mutazioni di questo gene nell'uomo possono causare sia la KS che il nCHH e che siano associate a un’estrema varaiblità fenotipica sia intra che inter-familiare. A seguito dei risultati ottenuti, abbiamo deciso di focalizzare la seconda parte di questo lavoro sulla caratterizzazione di queste varianti in vitro e in vivo allo scopo di meglio chiarire il ruolo del recettore della prochineticina 2 durante il processo di migrazione dei neuroni GnRH e ,di conseguenza, nel CHH. In particolare abbiamo caratterizzato dal punto di vista farmacologico le 4 varianti di nuova identificazione (p.G70S, p.D99N, p.C208S, p.M278K) unitamente ad altre 4 varianti già note in letteratura (p.R47W, p.M64V, p.R85H, p.P290S) ma ancora prive di caratterizzazione funzionale. Gli studi funzionali condotti hanno rivelato come queste varianti alleliche missenso possano influire in grado differente e indipendente sia sui meccanismi di trasporto in membrana del recettore PROKR2 che sulle vie di trasduzione del segnale intracellulari (Gs e Gq) da quest`ultimo mediate. In particolare, le varianti alleliche p.G70S, p.C208S e p.P290S producono una grave compromissione sia del meccanismo di trasporto in membrana che dell`attivazione delle vie Gs e Gq, mentre le mutazioni p.R47W, p.M64V e p.R85H colpiscono principalmente il trasporto in membrana. E` inoltre interessante notare come le varianti p.M278K e p.D99N , in seguito a stimolazione, hanno mostrato una quasi assente attivazione della via Gs in presenza di una buona conservazione nella funzionalita` della via Gq. Questi risultati sottolineano la necessità di valutare l'integrità di entrambi i meccanismi mediati da PROKR2: produzione di cAMP attraverso la via Gq e accumulo intracellulare di inositolo fosfato (IP) attraverso la via Gs, per un corretta valutazione dell`impatto funzionale delle varianti alleliche ritrovate. La parte finale di questo lavoro è stata incentrata sulla generazione di un modello in vivo per studiare il ruolo di PROKR2 nella migrazione dei neuroni GnRH utilizzando il modello animale di zebrafish (ZF). Pochi dati sono attualmente disponibili in letteratura sui recettori delle prochineticine in zebrafish. L'analisi bioinformatica condotta preliminarmente ha rivelato la presenza di due loci ben conservati all`interno del genoma di ZF: uno situato su chr1 ,denominato prokr1a, e una regione sul chr13, denominata prokr1b. Per valutare la loro espressione durante lo sviluppo di zebrafish, sono stati effettuati esperimenti di qRT-PCR Real-Time e Whole mount In Situ Hybridization (WISH) i quali hanno evidenziato un`espressione del solo gene prokr1b nei territori di migrazione ed espressione del gene GnRH3 (omologo in ZF di GnRH umano). Al fine di comprendere i ruoli funzionali di prokr1a e prokr1b, sono stati successivamente eseguiti esperimenti di knockdown iniettando sequenze oligonucletidiche sintetiche antisenso chiamate morpholino. I risultati hanno mostrato come la downregolazione di prokr1b, ma non prokr1a, colpisca la migrazione dei neuroni GnRH3 suggerendo cosi che prokr1b sia il gene omologo di PROKR2 umano. Per analizzare ulteriormente l'impatto di prokr1b sulla migrazione dei neuroni GnRH, e` stata inoltre generata una linea ZF knockout per il gene prokr1b. L` analisi delle fibre nervose dei neuroni GnRH in questa linea knockout ha mostrato gli stessi difetti di migrazione osservati durante gli esperimenti di downregolazione confermando cosi il ruolo di prokr1b nella migrazione dei neuroni GnRH. In conclusione, il presente lavoro di dottorato rappresenta l`applicazione di un approccio multidisciplinare per studiare i meccanismi genetici e molecolari coinvolti nel CHH, concentrandosi sul ruolo del gene PROKR2 in questa patologia. Attraverso analisi genetiche e` stato infatti possibile identificare nuove varianti genetiche di PROKR2 le quali, attraverso esperimenti in vitro, sono state farmacologicamente caratterizzate permettendo di evidenziare come le varianti possano influenzare in maniera differente le via di trasduzione del segnale intracellulari mediate dal recettore o il meccanismo di traslocazione in membrana. Infine, attraverso esperimenti di knockdown e knockout, e` stato identificato in zebrafish il gene ortologo di PROKR2 umano e generato un nuovo modello in vivo, che potrebbe essere importante al fine di svelare il ruolo preciso del pathway prochineticine nella patogenesi di CHH.
Congenital hypogonadotropic hypogonadism (CHH) is a rare disease characterized by delayed/absent puberty and infertility due to an inadequate secretion or action of gonadotrophin-releasing hormone (GnRH). CHH is genetically heterogeneous but, due to the infertility of affected individuals, most frequently emerges in a sporadic form, though numerous familial cases have also been registered. In around 50-60% of cases, CHH is associated with a variety of non-reproductive abnormalities, most commonly anosmia/hyposmia, which defines Kallmann syndrome (KS) by its presence. Broadly speaking, genetic defects that directly impact on hypothalamic secretion, regulation, or action of GnRH result in a pure neuroendocrine phenotype called normosmic CHH (nCHH), whereas genetic defects that impact of embryonic migration of GnRH neurons to the hypothalamus most commonly result in KS, though nCHH can also arise. CHH represents a difficult unresolved puzzle, although more than 25 genes have been described to be involved in CHH, molecular variants can explain only 35-45% of reported cases. These evidences raise in the last year the idea that CHH is an oligogenic complex genetic disease characterized by variable expressivity and penetrance. With the purpose to better understand the genetic component of CHH, the first part of this work was focused on genetic screening of the principal twelve genes involved in CHH on the largest cohort of Italian patients. Screening of a cohort of 512 CHH patients allows the identification of 204 total variants in 32.2% of clinical cases. The analysis of variants displays a oligogenicity of 4.6%, confirming the oligogenic nature of CHH. Between the genes that appeared more frequently involved in the identified allelic variant, PROKR2 gene appears in 7.5% of the cases. Indeed we identified a total of 17 PROKR2 allelic variants, being four novel variants (p.G70S, p.D99N, p.C208S, p.M278K). PROKR2 gene is known to have an important and not fully understood role in GnRH neurons migration, and mutations of this gene in humans can cause KS or nCHH syndromes with a phenotypic heterogeneity of reproductive and olfactory defects. Consequently we decided to focus the second part of this work on characterization of these variants in vitro and in vivo with the aim to better elucidate the role of prokineticin receptor 2 in CHH and GnRH neurons migration. PROKR2 GPCR signal transduction pathways functionality was studied in the above mentioned 4 novel and in other 4 already described variants that lack extensive functional studies (p.R47W, p.M64V, p.R85H, p.P290S). The functional study revealed that these missense allelic variants can affect protein targeting and signaling pathways with variable degree. In particular p.G70S, p.C208S and p.P290S are the more compromised with a general impairment for both protein trafficking and Gs/Gq intracellular transduction pathways, while p.R47W, p.M64V and p.R85H variants are mainly affected in their targeting to the cell membrane, event thought with a still conserved activation. Interestingly, p.M278K and p.D99N variants showed a virtual lack of the Gs-pathway activation in the presence of a conserved response to the Gq-pathway stimulation. These findings indicate the need to evaluate the integrity of both PROKR2-dependent cAMP and IP intracellular accumulation for a more appropriate functional testing of novel identified allelic variants. The final part of this work was focused on generating an in vivo model for studying the role of PROKR2 in the migration of GnRH neurons using zebrafish animal model. Few data are available on literature about prokineticin receptors in zebrafish. Preliminary bioinformatics analysis revealed the presence of two well-conserved loci in the zebrafish genome, located on chr1, named prokr1a, and a predicted region on chr13 named prokr1b. To assess their expression during zebrafish development, we perfomed Real-Time qRT-PCR and whole mount In Situ Hybridization (WISH). For investigating the functional roles of prokr1a and prokr1b, knockdown experiments were performed injecting morpholino sequences. Downregulation of prokr1b, but not prokr1a affects the migration/architecture of GnRH3 neurons supporting the idea that prokr1b is the homologous gene of human PROKR2. To further analyze the impact of prokr1b on GnRH neurons migration, a ZF prokr1b knockout line was generated. Analysis of GnRH fibers network in zebrafish knockout line display the same migration defects observed during downregulation assay, confirming the role of prokr1b in the migrations of GnRH neurons. In conclusion, in the present work we applied a multidisciplinary approach to better elucidate the genetic and molecular mechanisms involved in CHH, focusing on the role of PROKR2 gene. Starting from genetic analysis we identified PROKR2 variants that were pharmacologically characterized by in vitro experiments to evaluate how these variants can affect signaling pathway or receptor membrane traslocation. Moreover, with expression and knockdown experiments, we identified the zebrafish PROKR2 human ortholog and generate a new in vivo model, that will be important in order to unravel the precise role of the prokineticin pathway in the pathogenesis of CHH.

O Hipogonadismo hipogonadotrófico isolado (HHI) congênito é uma síndrome clínica rara causada por defeito na produção ou secreção do hormônio liberador de gonadotrofinas (GnRH) pelo hipotálamo ou por resistência hipofisária à ação do GnRH. O HHI é mais prevalente em homens e cerca de 50% a 60% dos indivíduos afetados apresentam anosmia ou hiposmia associada, caracterizando a síndrome de Kallmann. Diversos genes já foram associados à patogênese do HHI congênito, porém, a maioria dos casos ainda permanece sem diagnóstico molecular definido. Até recentemente, a identificação das causas genéticas dos pacientes com HHI era realizada por sequenciamento de genes candidatos, empregando a técnica de Sanger. No entanto, com o número crescente de genes descritos nos últimos anos, esse processo vem se tornando impraticável. Novas metodologias de sequenciamento (sequenciamento paralelo em larga escala) foram desenvolvidas permitindo a genotipagem simultânea de diversas regiões, com maior velocidade e menor custo relativo. O atual projeto foi desenvolvido com o objetivo de rastrear genes candidatos em pacientes portadores de HHI congênito utilizando-se o sequenciamento paralelo em larga escala, visando ampliar o conhecimento genético do HHI. Realizamos o sequenciamento paralelo em larga escala (SPLE) de 130 pacientes com HHI congênito utilizando um painel contendo 36 genes relacionados ao HHI. Inicialmente, identificamos 104 variantes, potencialmente patogênicas em 77 pacientes (59,2%). Após a filtragem inicial, foi realizada uma análise individualizada de cada variante e com isso foram mantidos 41 (31,5%) pacientes com variantes classificadas como patogênicas ou provavelmente patogênicas. Os genes KAL1, FGFR1, CHD7 e GNRHR foram os mais frequentemente afetados. Esses resultados confirmam a importância dos genes classicamente associados ao HHI congênito. Destaca-se a alta prevalência de variantes no CHD7 (10,8%), gene bastante extenso, levando à dificuldade técnica de sequenciá-lo pelos métodos tradicionais, até então sem estudos nessa coorte. O CHD7 é um gene originalmente associado à complexa síndrome de CHARGE, porém, nos últimos anos vem sendo cada vez mais associados ao HHI congênito. Dentre os resultados, ressaltamos a identificação de uma mutação inédita no gene GNRH1, causa rara de HHI, e a identificação de variantes deletérias no gene IGSF10, recentemente descrito associado ao atraso puberal, mas sem papel claro no fenótipo de HHI, em dois pacientes que tiveram reversibilidade do hipogonadismo. Variantes provavelmente patogênicas em genes com poucas descrições ou até mesmo sem relatos de associação ao fenótipo de HHI (SPRY4, FLRT3, IGSF1, NSMF, SOX10 e OTX2) também foram identificadas nessa coorte, ampliando nosso conhecimento genético do HHI. A oligogenicidade, previamente descrita com prevalência de 2,5% a 7%, em nosso estudo esteve presente em 22% dos pacientes, demonstrando uma ampliação das descrições de oligogenicidade quando comparados aos estudos prévios utilizando somente a técnica de Sanger. A nova técnica de sequenciamento genético (SPLE), utilizada em nosso estudo, foi capaz de ampliar de 22% para 31,5% (41 em 130 pacientes) a porcentagem de pacientes com diagnóstico molecular definido, quando comparado aos dados prévios utilizando a técnica de Sanger, mostrando-se rápida, confiável e eficaz
Congenital isolated hypogonadotropic hypogonadism (IHH) is a rare condition caused by GnRH deficiency, due to defective hypothalamic gonadotropin-releasing hormone (GnRH) production or secretion, or by pituitary resistance to the GnRH action. Congenital IHH is more prevalent in men and about 50% to 60% of affected individuals present with associated anosmia or hyposmia, characterizing Kallmann\'s syndrome. Several genes have already been associated with the pathogenesis of congenital IHH, but most cases still remain without a molecular diagnosis. Until recently, identification of the genetic causes of IHH was performed by sequencing candidate genes using the Sanger technique. However, with the growing number of genes and the genetic complexity of IHH, it has become almost impossible to keep the screening of all candidate genes updated using the traditional techniques. The advent of next-generation sequencing (NGS) has allowed the simultaneous genotyping of several regions, faster and with lower relative cost. The present project was developed with the objective of tracking candidate genes in patients with congenital IHH using large-scale parallel sequencing, in aiming to increase the genetic knowledge of this rare condition. A total of 130 unrelated patients with IHH was studied by targeted NGS, using a panel containing 36 IHH associated genes. Initially, 104 potentially pathogenic variants were identified in 77 patients (59.2%). However, after an individualized analysis of each variant, the number of patients considered to carry pathogenic or probably pathogenic variants dropped to 41 (31.5%). The genes KAL1, FGFR1, CHD7 and GNRHR were the most frequently affected and these results confirm the importance of genes classically associated with IHH. It is noteworthy the high prevalence of variants in CHD7 (10.8%), a rather extensive gene, leading to technical difficulty of sequencing by traditional methods, which had not been studied in this cohort. CHD7 is the causative gene of CHARGE syndrome, however it has been recently identified in a growing number of congenital IHH patients with or without additional features of the syndrome. Among the results, we emphasize a novel mutation in the GNRH1 gene, a rare cause of IHH, and the identification of deleterious variants in the IGSF10 gene, recently associated with pubertal delay but without a clear role in the IHH phenotype, in two patients with reversible hypogonadism. Probably pathogenic variants in genes with few descriptions or even no reports of association with the IHH phenotype (SPRY4, FLRT3, IGSF1, NSMF, SOX10 and OTX2) were also identified in this cohort, increasing the genetic knowledge of IHH. Oligogenicity, previously described with a prevalence of 2.5% to 7%, was observed in 22% of our patients, demonstrating an increase in oligogenicity cases when compared to previous studies using only the Sanger sequencing. In conclusion, targeted NGS was able to increase the percentage of patients with molecular diagnosis from 22% to 31.5% in our cohort when compared to the previous data using the Sanger sequencing, and has been shown to be a fast, reliable and effective tool in the molecular diagnosis of congenital IHH

Currently, NGS-based genetic testing has become an indispensable component of the comprehensive diagnostic workup in rare endocrine diseases. For this reason, our clinical genetics laboratory has designed a custom NGS panel including all the known candidate and susceptibility genes for Congenital Hypogonadotropic Hypogonadism (CHH) and Pheochromocytoma/Paraganglioma (Pheo/PGL/HNPGL), respectively. In addition, the VHL mutational screening has been developed to diagnose the von Hippel-Lindau syndrome (VHL) in suspected cases. This study aimed to evaluate the diagnostic yield basedon genetic testing in the above-mentioned rare endocrine diseases. After the NGS sequencing, a comprehensive bioinformatic analysis of each variant was performed in order to evaluate their pathogenicity and genotype-phenotype correlations were examined. The first part of this thesis focused on CHH, which is a congenital disorder covering a widespectrum of signs/symptoms, from classical forms with absent puberty, including Kallmannsyndrome and other syndromic conditions, to milder forms with Adult-Onset Hypogonadism (AOH). To date more than 40 candidate genes have been identified in approximately 40-50% of cases with a genetic diagnosis of CHH. We have enrolled 26 affected patients, of whom 12 showed the classic forms of disease whereas 14 were AOH. The total genetic diagnostic yield of our NGS panel, including 34 candidate genes with strong/definitive clinical evidence, was 23%, with the highest diagnostic rate in classic forms (42%) and the lowest one in the AOH (7%). The majority of mutated genes are well knowncausative genes, with the exception of DMXL2, for which only a few familial cases have beendescribed so far. Interestingly, the unique case of AOH with a clear genetic diagnosis carriedan affected DMXL2 allele, which is responsible for a mild reproductive phenotype, according to the literature. Our finding contributes to elucidate the role of DMXL2 gene in the aetiology of CHH. The second part of this thesis focused on rare endocrine tumours. Among them, Pheo/PGL/HNPGL arise from neural crest cells and affect adrenal gland (Pheo) or extra-adrenal sites (PGL/HNPGL). More than 20 susceptibility genes have been reported to predispose to Pheo/PGL/HNPGL, with a diagnostic yield of approximately 30%. On the other hand, the VHL syndrome is a monogenic disorder arising from germline mutations in the VHL gene and involving multiple organs. All these conditions follow an autosomal mode of inheritance, with an incomplete and age-dependent penetrance related to the specific gene defect. We have enrolled 95 patients affected by Pheo/PGL/HNPGL and 8 suspected VHL cases. Concerning the former, our NGS panel containing 15 susceptibility genes revealed a genetic diagnostic yield of 20%, with the highest diagnostic rate in PGLs (33%) and the lowest one in Pheos (14%). The majority of mutated genes belongs to the SDHx family, in line with previous data. Interestingly, one Pheo patient carrying two germline defects in the SDHD and VHL genes received a diagnosis of VHL syndrome, thanks to the gene panel results. Regarding patients with suspected VHL, we diagnosed a “true” VHL syndrome in 25% of cases. This study highlights the power of genetic testing as a diagnostic tool with relevant implications in genetic counselling and clinical management of the mutation carriers. Based on our results, CHH patients should be well-characterized prior to genetic testing, as the presence of a disease-causing genotype is almost exclusively found in classic forms. Hence, the genotype of AOH patients seems to be different from those with CHH. In case of rare endocrine tumours, we confirmed that genetic testing is relevant for correct and early diagnosis, leading to a better prognosis and to an appropriate treatment, of both the patient and her/his family members through an active surveillance.