👤 Duarte Pignatelli

Congenital hypogonadotropic hypogonadism (CHH) is a rare and genetically heterogeneous disorder characterized by absent or incomplete puberty due to impaired gonadotropin-releasing hormone (GnRH) function. A subset of individuals with CHH also present with developmental anomalies, including midline defects such as cleft lip and/or palate (CLP). This study investigates the genetic overlap between CHH and CLP. A total of 336 individuals diagnosed with CHH were clinically assessed for associated phenotypes, including CLP. High-throughput sequencing was performed using a targeted gene panel encompassing known CHH- and CLP-related genes. Variants were analyzed and classified according to the American College of Medical Genetics and Genomics (ACMG) criteria for pathogenicity. CLP was present in 21 patients with CHH (6%). Pathogenic or likely pathogenic variants in genes associated with both CHH and CLP-such as FGFR1 and CHD7-were identified in eight individuals. Furthermore, 17% of the patients with CHH without CLP harbored deleterious variants in genes implicated in clefting, including DVL3, PLCB4, NIPBL, and EDNRA. Evidence of digenic inheritance involving both CHH- and CLP-related genes was observed in multiple cases. FGFR1 variants were the most frequently detected and were commonly associated with anosmia and additional developmental anomalies. These findings highlight a genetic and phenotypic continuum between CHH and CLP, underscoring the involvement of shared developmental pathways. The high prevalence of FGFR1 variants in patients with CHH and CLP supports its role as a pleiotropic gene. Understanding the overlapping genetic mechanisms may enhance diagnostic precision and inform personalized management strategies for affected individuals. Show less

What is the contribution of genetic defects in Portuguese patients with congenital hypogonadotropic hypogonadism (CHH)? Approximately one-third of patients with CHH were found to have a genetic cause for their disorder, with causal pathogenic and likely pathogenic germline variants distributed among 10 different genes; cases of oligogenic inheritance were also included. CHH is a rare and genetically heterogeneous disorder characterized by deficient production, secretion, or action of GnRH, LH, and FSH, resulting in delayed or absent puberty, and infertility. Genetic screening was performed on a cohort of 81 Portuguese patients with CHH (36 with Kallmann syndrome and 45 with normosmic hypogonadotropic hypogonadism) and 263 unaffected controls. The genetic analysis was performed by whole-exome sequencing followed by the analysis of a virtual panel of 169 CHH-associated genes. The main outcome measures were non-synonymous rare sequence variants (population allele frequency <0.01) classified as pathogenic, likely pathogenic, and variants of uncertain significance (VUS). A genetic cause was identified in 29.6% of patients. Causal pathogenic and likely pathogenic variants were distributed among 10 of the analysed genes. The most frequently implicated genes were N/A. The identification of a large number of VUS presents challenges in interpretation and these may require reclassification as more evidence becomes available. Non-coding and copy number variants were not studied. Functional studies of the variants were not undertaken. This study highlights the genetic heterogeneity of CHH and identified several novel variants that expand the mutational spectrum of the disorder. A significant proportion of patients remained without a genetic diagnosis, suggesting the involvement of additional genetic, epigenetic, or environmental factors. The high frequency of VUS underscores the importance of cautious variant interpretation. These findings contribute to the understanding of the genetic architecture of CHH and emphasize the need for further studies to elucidate the underlying mechanisms and identify additional causes of CHH. This research was funded by the Portuguese Foundation for Science and Technology (grant numbers PTDC/SAU-GMG/098419/2008, UIDB/00709/2020, CEECINST/00016/2021/CP2828/CT0002, and 2020.04924.BD) and by Sidra Medicine-a member of the Qatar Foundation (grant number SDR400038). The authors declare no competing interests. Show less