X­chromosome loss rescues Sertoli cell maturation and spermatogenesis in Klinefelter syndrome.

Klinefelter syndrome (47,XXY) causes infertility with a testicular histology comprising two types of Sertoli cell-only tubules, representing mature and immature-like Sertoli cells, and occasionally focal spermatogenesis. Here, we show that the immature-like Sertoli cells highly expressed XIST and had two X-chromosomes, while the mature Sertoli cells lacked XIST expression and had only one X-chromosome. Sertoli cells supporting focal spermatogenesis also lacked XIST expression and the additional X-chromosome, while the spermatogonia expressed XIST despite having only one X-chromosome. XIST was expressed in Sertoli cells until puberty, where a gradual loss was observed. Our results suggest that a micro-mosaic loss of the additional X-chromosome is needed for Sertoli cells to mature and to allow focal spermatogenesis.

Markers of Fertility in Adolescents With Chronic Endocrinopathies at Transition From Paediatric to Adult Care.

OBJECTIVE: During the process of transition from paediatric to adult health care, counselling concerning fertility is an important issue and is based mainly on serum markers of gonadal function. Here, we analysed these markers in adolescents with various underlying endocrine diseases at the time of transition. METHODS: After reaching near adult height and late puberty (girls: bone age [BA] ≥14 years, and boys: BA ≥16 years), we assessed stages of puberty according to Tanner and measured testes or ovarian volumes and serum markers of gonadal function (anti-Mullerian hormone [AMH], inhibin B, 17ß-estradiol, testosterone). RESULTS: One hundred and ten patients (56 females and 54 males) were included from May 2010 to March 2016 with multiple pituitary hormone deficiency (MPHD; n = 17), growth hormone deficiency (GHD; n = 35), Turner syndrome (TS; n = 27), short stature after being born small for gestational age (SGA; n = 20) and Klinefelter syndrome (KS; n = 11). Female and male adolescents exhibited mature secondary sexual characteristics. The levels of serum inhibin B and AMH were lower in TS and female MPHD than in GHD and SGA, each independently (p < 0.05). The levels of serum AMH were higher whereas serum inhibin B were lower in male MPHD and KS (p < 0.05). Ovary volumes were significantly smaller in patients with TS, and testicular volumes were smaller in patients with KS. CONCLUSIONS: After current established treatments with sex steroids, the development of secondary sexual characteristics was mature. However, impaired markers of fertility have been identified in patients with TS, KS and MPHD, reflecting gonadal dysgenesis in TS and KS, but gonadal immaturity in MPHD as gonadal gonadotropin stimulation is lacking throughout development. Consequently, in patients with MPHD, these markers cannot reliably predict individual fertility, which warrants consideration and incorporation in future treatment concepts.

Giftedness and atypical sexual differentiation: enhanced perceptual functioning through estrogen deficiency instead of androgen excess.

Syndromic autism spectrum conditions (ASC), such as Klinefelter syndrome, also manifest hypogonadism. Compared to the popular Extreme Male Brain theory, the Enhanced Perceptual Functioning model explains the connection between ASC, savant traits, and giftedness more seamlessly, and their co-emergence with atypical sexual differentiation. Overexcitability of primary sensory inputs generates a relative enhancement of local to global processing of stimuli, hindering the abstraction of communication signals, in contrast to the extraordinary local information processing skills in some individuals. Weaker inhibitory function through gamma-aminobutyric acid type A (GABAA) receptors and the atypicality of synapse formation lead to this difference, and the formation of unique neural circuits that process external information. Additionally, deficiency in monitoring inner sensory information leads to alexithymia (inability to distinguish one's own emotions), which can be caused by hypoactivity of estrogen and oxytocin in the interoceptive neural circuits, comprising the anterior insular and cingulate gyri. These areas are also part of the Salience Network, which switches between the Central Executive Network for external tasks and the Default Mode Network for self-referential mind wandering. Exploring the possibility that estrogen deficiency since early development interrupts GABA shift, causing sensory processing atypicality, it helps to evaluate the co-occurrence of ASC with attention deficit hyperactivity disorder, dyslexia, and schizophrenia based on phenotypic and physiological bases. It also provides clues for understanding the common underpinnings of these neurodevelopmental disorders and gifted populations.

Hormone Therapy During Infancy or Early Childhood for Patients with Hypogonadotropic Hypogonadism, Klinefelter or Turner Syndrome: Has the Time Come?

Managing patients unable to produce sex steroids using gonadotropins to mimic minipuberty in hypogonadotropic hypogonadism, or sex steroids in patients with Klinefelter or Turner syndrome, is promising. There is a need to pursue research in this area, with large prospective cohorts and long-term data before these treatments can be routinely considered.

Macular hypoplasia and high myopia in 48, xxyy syndrome: a unique case of 48, xxyy syndrome that presents with high myopia and macular dysplasia.

BACKGROUND: Among sex chromosome aneuploidies, 48, XXYY syndrome is a rare variant. This condition is marked by the existence of an additional X and Y chromosome in males, leading to a diverse range of physical, neurocognitive, behavioral, and psychological manifestations. Typical characteristics include a tall stature and infertility. Other phenotypes include congenital heart defects, skeletal anomalies, tremors, obesity, as well as the potential for type 2 diabetes and/or peripheral vascular disease. CASE PRESENTATION: A 6-year-old boy, who had been experiencing progressive vision deterioration in both eyes for the past two years, presented with a history of poor vision, delayed motor skills. The patient was diagnosed with micropenis in the pediatric outpatient clinic. Sparse hair, an unusually tall stature and craniofacial dysmorphology characterized by ocular hypertelorism, depressed nasal bridge, and epicanthic folds were observed. Comprehensive ophthalmic examination revealed high myopia and grade 3 macular hypoplasia. Diagnostic investigations including karyotype analysis and whole-exome sequencing identified an anomalous male karyotype comprising two X and two Y chromosomes, confirming a diagnosis of 48, XXYY syndrome. CONCLUSIONS: This study underscores the rare association of high myopia and grade 3 macular dysplasia with 48, XXYY syndrome. To our knowledge, this case marks the first recorded instance of macular dysplasia in a patient with 48, XXYY syndrome. This novel finding enhances our understanding of this syndrome's phenotypic variability.

Mediastinal Germ-cell Tumors Relapse in a Male With Klinefelter Syndrome. Is Longer Surveillance Needed?

Germ cell tumors (GCTs) are a heterogeneous group of pediatric cancers. In up to one-third of male patients, a primary mediastinal location is associated with the presence of Klinefelter syndrome (KS). We describe a case of mediastinal GCT in a patient, with unacknowledged KS, that presented a relapse 7 years from diagnosis, that is, 2 years after the end of the follow-up program usually recommended for patients with GCT. There are no recommendations for screening for KS in patients with mediastinal GCT and there are no specific guidelines for surveillance of GCT in KS patients. Our experience suggests that KS should be suspected in patients with mediastinal GCT, and a longer follow-up plan should be implemented when GCT occurs in patients with KS.

Serum Lipocalin-2 Levels as a Biomarker in Pre- and Post-Pubertal Klinefelter Syndrome Patients: A Pilot Study.

Klinefelter syndrome (KS) is a male genetic disease caused by the presence of an extra X chromosome, causing endocrine disorders mainly responsible for a high rate of infertility and metabolic disorders in adulthood. Scientific research is interested in identifying new biomarkers that can be predictive or prognostic of alterations strictly connected to KS. Lipocalin-2 (LCN-2, also known as NGAL) is a small protein initially identified within neutrophils as a protein related to innate immunity. Serum LCN-2 estimation seems to be a useful tool in predicting the metabolic complications caused by several pathological conditions. However, little is known about its potential role in infertility conditions. The present pilot study aims to investigate the presence of LCN-2 in the serum of a group of pre-pubertal and post-pubertal children affected by KS, compared to healthy controls. We demonstrated for the first time the presence of elevated levels of LCN-2 in the serum of KS patients, compared to controls. This increase was accompanied, in pre-pubertal KS patients, by the loss of correlation with LH and HDL, which instead was present in the healthy individuals. Moreover, in all KS individuals, a positive correlation between LCN-2 and inhibin B serum concentration was found. Despite the limited size of the sample analyzed, our preliminary data encourage further studies to confirm the findings and to extend the study to KS adult patients, to verify the predictive/prognostic value of LCN-2 as new biomarker for metabolic diseases and infertility associated with the pathology.

Generation of iPSC Cell Lines from Patients with Sex Chromosome Aneuploidies.

Somatic cell reprogramming allows the generation of human induced pluripotent stem cells (iPSCs) from patient's cells. The derived iPSCs provide an unlimited source of patient-specific cells that can be virtually differentiated in any cell of the human body. The generation of iPSCs has important implications for all human medicine fields, as they can be used for drug discovery, regenerative medicine, and developmental studies. Klinefelter Syndrome (KS) is the most common chromosome aneuploidy in males. KS is typically characterized by a 47,XXY karyotype, representing 80-90% of KS patients. In rare cases, high-grade sex chromosome aneuploidies (SCAs), 48,XXXY; 48,XXYY; 49,XXXXY, are also observed in males. Since the advent of the reprogramming technique, a few KS-iPSCs have been described. Here, we detail the methodology for generating primary fibroblasts from patients' skin biopsies and the subsequent derivation of iPSCs using an efficient integrative-free mRNA-based somatic reprogramming approach.

Detection of chromosomal aneuploidy in ancient genomes.

Ancient DNA is a valuable tool for investigating genetic and evolutionary history that can also provide detailed profiles of the lives of ancient individuals. In this study, we develop a generalised computational approach to detect aneuploidies (atypical autosomal and sex chromosome karyotypes) in the ancient genetic record and distinguish such karyotypes from contamination. We confirm that aneuploidies can be detected even in low-coverage genomes ( ~ 0.0001-fold), common in ancient DNA. We apply this method to ancient skeletal remains from Britain to document the first instance of mosaic Turner syndrome (45,X0/46,XX) in the ancient genetic record in an Iron Age individual sequenced to average 9-fold coverage, the earliest known incidence of an individual with a 47,XYY karyotype from the Early Medieval period, as well as individuals with Klinefelter (47,XXY) and Down syndrome (47,XY, + 21). Overall, our approach provides an accessible and automated framework allowing for the detection of individuals with aneuploidies, which extends previous binary approaches. This tool can facilitate the interpretation of burial context and living conditions, as well as elucidate past perceptions of biological sex and people with diverse biological traits.

A rare case of adult-onset spastic paraparesis associated with Klinefelter syndrome.

REPORT: The rare association of Klinefelter syndrome and the clinical presentation of a late onset chronic progressive spastic paresis. CLINICAL PRESENTATION AND GENETICS: An infertile, 61-year-old man, presented with late adult onset of gait problems, deep muscle pain, and bladder problems. He presented for the first time, years after onset with a spastic paraparesis with high arched feet. His parents had already died, but the patient described high arched feet with his mother. There is no further certain information about the parents. After thorough investigation, an additional X chromosome was found, whereafter the diagnosis of Klinefelter syndrome could be made. Other acquired and genetic causes for spastic paraparesis or hereditary motor neuropathy are excluded. CONCLUSION: This rare case, together with three other literature reports by Sasaki (Intern Med 58(3):437-440, 2019), Sajra (Med Arh 61(1):52-53, 2007) and Matsubara et al., (J Neurol Neurosurg Psychiatry 57(5):640-642, 1994). suggests that Klinefelter syndrome can be associated with spastic paraparesis, besides the other various neuropsychiatric symptoms that are more commonly described.

Testosterone Replacement Therapy in Klinefelter Syndrome-Follow-up Study Associating Hemostasis and RNA Expression.

BACKGROUND: Men with Klinefelter syndrome (KS) develop hypergonadotropic hypogonadism, are in need of testosterone replacement therapy (TRT), and present with a more than 4-fold increased risk of thrombosis. TRT in KS has the potential to modify thrombotic risk, but data are scarce. AIM: To assess effects of 18 months of TRT on hemostasis in KS and identify genes associated with the prothrombotic phenotype. METHODS: Untreated and TRT-treated men with KS were included at baseline and matched to healthy controls. TRT was initiated in untreated KS and all groups were reassessed after 18 months of follow-up. Thrombin generation was evaluated with or without thrombomodulin, and fibrin clot lysis was evaluated by turbidity measurements. RNA expression was assessed in blood, fat, and muscle tissue of patients with TRT-treated KS and controls. RESULTS: Thrombin generation with thrombomodulin was slightly increased in untreated KS, but overall KS was not associated with a hypercoagulable state. KS presented with fibrinolytic impairment associated with higher body fat and higher levels of fibrinogen. Eighteen months of TRT in KS was associated with a reduction in body fat and fibrinogen, attenuating the prothrombotic profile. The expression of ENPP4 was higher in men with KS and served as a key player among a group of genes associated with impaired fibrinolysis. CONCLUSION: KS is associated with a specific expression profile contributing to fibrinolytic impairment and increased thrombotic risk in the patients. TRT in patients with KS has the potential for alleviating the prothrombotic phenotype, in particular by reducing body fat and fibrinogen.

Microdissection testicular sperm extraction outcomes in azoospermic patients with bilateral orchidopexy.

BACKGROUND: Cryptorchidism is considered to be one of the most common causes of non-obstructive azoospermia. There are several surgical techniques to retrieve sperm in these patients. Microdissection testicular sperm extraction (m-TESE) is a recent sperm retrieval technique which is considered to be a safe, non-blind, and feasible method. OBJECTIVES: This study aimed to investigate sperm retrieval rate (SRR) by the mTESE method in patients who have undergone orchidopexy due to bilateral cryptorchidism. MATERIALS AND METHODS: In this retrospective study, 56 ex-cryptorchid patients, who underwent mTESE due to post orchidopexy azoospermia, were included. Patients with hypogonadotropic hypogonadism, Klinefelter syndrome, azoospermia factors (AZF) microdeletion, or chromosomal translocation were excluded from the study. Data were obtained from medical files. RESULTS: SRR in this study was 46%. Patients were divided into two groups of negative (n = 30) and positive (n = 26) based on the sperm extraction outcomes. There was no statistically significant difference between two groups regarding the mean age at mTESE, mean age at orchidopexy, testicular size, and serum testosterone concentration. However, testicular location, histological patterns, FSH, and LH level showed to have statistically significant relation with sperm retrieval results. But, according to our logistic regression, none of the included variable in the model including FSH, LH, histopathology, and testis location have a significant effect on the presence of the sperm. DISCUSSION: In the present study, SRR was significantly higher in patients with scrotal testis and low level of FSH and LH. CONCLUSIONS: Performing mTESE could be recommended in ex-cryptorchid patients with post orchidopexy NOA. Preoperative testicular biopsy seems to be unnecessary while clinical criteria can perfectly define NOA.

Mixed hypogonadism: a neglected combined form of hypogonadism.

PURPOSE: Kallmann syndrome is a rare disease characterized by delayed puberty, infertility and anosmia. We report the clinical and genetic characteristics of three patients with Kallmann syndrome who presented with Klinefelter syndrome and defined this neglected combined form of hypogonadism as mixed hypogonadism. METHODS: Clinical data and examinations were obtained, including laboratory examination and magnetic resonance imagination (MRI) of the olfactory structures. Congenital hypogonadotropic hypogonadism (CHH) related genes were screened by next generation sequencing (NGS). RESULTS: Three patients with Kallmann syndrome were included. They had co-existence with Klinefelter syndrome and showed hypogonadotropic hypogonadism. Patient 1 was complicated with germinoma. CONCLUSION: Mixed hypogonadism was defined as hypogonadotropic hypogonadism in Klinefelter syndrome or primary testicular disease. Clinicians should be alert to mixed hypogonadism when spermatogenesis induction failed in patients with CHH or gonadotropin levels decrease in patients with Klinefelter syndrome.

Age, Sperm Retrieval, and Testicular Histology in Klinefelter Syndrome.

PURPOSE: We sought to examine sperm retrieval and testicular histology in males of different ages with Klinefelter syndrome. MATERIALS AND METHODS: We identified all males with Klinefelter syndrome who underwent microdissection testicular sperm extraction at our institution from 1995 to 2020. Patients were divided into adolescent (<20 years) and adult (≥20 years) cohorts. Histology and sperm retrieval were compared using chi-square statistics. Multivariable logistic regression models were used to examine factors associated with successful sperm retrieval. RESULTS: We identified 217 males with Klinefelter syndrome, of whom 59 were adolescents and 158 were adults. Adults were stratified into 10-year groupings (20-29 years, n = 62; 30-39 years, n = 88; ≥40 years, n = 8). Approximately 17% of adolescents had testis histology containing germ cells compared with 15% of the 20 to 29-year cohort, 14% of the 30 to 39-year cohort, and 0% over 40 years. In comparison to adolescents (53%), the sperm retrieval rate was significantly higher in the 20 to 29-year cohort (71%, P = .04) and lower in the ≥40-year cohort (13%, P = .03). In multivariable analysis, the presence of hypospermatogenesis on testis biopsy (OR 5.8, P = .03) was associated with higher odds of successful sperm retrieval. CONCLUSIONS: Younger males more frequently had germ cell-containing testis histology, however this finding was not associated with a higher odds of sperm retrieval. Reproductive urologists should counsel azoospermic males with Klinefelter syndrome that sperm retrieval during adolescence for fertility preservation is not required and can be performed in young adulthood.

Gonadotropins for pubertal induction in males with hypogonadotropic hypogonadism: systematic review and meta-analysis.

OBJECTIVE: Hypogonadotropic hypogonadism is characterized by inadequate secretion of pituitary gonadotropins, leading to absent, partial, or arrested puberty. In males, classical treatment with testosterone promotes virilization but not testicular growth or spermatogenesis. To quantify treatment practices and efficacy, we systematically reviewed all studies investigating gonadotropins for the achievement of pubertal outcomes in males with hypogonadotropic hypogonadism. DESIGN: Systematic review and meta-analysis. METHODS: A systematic review of Medline, Embase, Global Health, and PsycINFO databases in December 2022. Risk of Bias 2.0/Risk Of Bias In Non-randomized Studies of Interventions/National Heart, Lung, and Blood Institute tools for quality appraisal. Protocol registered on PROSPERO (CRD42022381713). RESULTS: After screening 3925 abstracts, 103 studies were identified including 5328 patients from 21 countries. The average age of participants was <25 years in 45.6% (n = 47) of studies. Studies utilized human chorionic gonadotropin (hCG) (n = 93, 90.3% of studies), human menopausal gonadotropin (n = 42, 40.8%), follicle-stimulating hormone (FSH) (n = 37, 35.9%), and gonadotropin-releasing hormone (28.2% n = 29). The median reported duration of treatment/follow-up was 18 months (interquartile range 10.5-24 months). Gonadotropins induced significant increases in testicular volume, penile size, and testosterone in over 98% of analyses. Spermatogenesis rates were higher with hCG + FSH (86%, 95% confidence interval [CI] 82%-91%) as compared with hCG alone (40%, 95% CI 25%-56%). However, study heterogeneity and treatment variability were high. CONCLUSIONS: This systematic review provides convincing evidence of the efficacy of gonadotropins for pubertal induction. However, there remains substantial heterogeneity in treatment choice, dose, duration, and outcomes assessed. Formal guidelines and randomized studies are needed.

Gonadotropin-Releasing Hormone Receptor (GnRHR) and Hypogonadotropic Hypogonadism.

Human sexual and reproductive development is regulated by the hypothalamic-pituitary-gonadal (HPG) axis, which is primarily controlled by the gonadotropin-releasing hormone (GnRH) acting on its receptor (GnRHR). Dysregulation of the axis leads to conditions such as congenital hypogonadotropic hypogonadism (CHH) and delayed puberty. The pathophysiology of GnRHR makes it a potential target for treatments in several reproductive diseases and in congenital adrenal hyperplasia. GnRHR belongs to the G protein-coupled receptor family and its GnRH ligand, when bound, activates several complex and tissue-specific signaling pathways. In the pituitary gonadotrope cells, it triggers the G protein subunit dissociation and initiates a cascade of events that lead to the production and secretion of the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) accompanied with the phospholipase C, inositol phosphate production, and protein kinase C activation. Pharmacologically, GnRHR can be modulated by synthetic analogues. Such analogues include the agonists, antagonists, and the pharmacoperones. The agonists stimulate the gonadotropin release and lead to receptor desensitization with prolonged use while the antagonists directly block the GnRHR and rapidly reduce the sex hormone production. Pharmacoperones include the most recent GnRHR therapeutic approaches that directly correct the misfolded GnRHRs, which are caused by genetic mutations and hold serious promise for CHH treatment. Understanding of the GnRHR's genomic and protein structure is crucial for the most appropriate assessing of the mutation impact. Such mutations in the GNRHR are linked to normosmic hypogonadotropic hypogonadism and lead to various clinical symptoms, including delayed puberty, infertility, and impaired sexual development. These mutations vary regarding their mode of inheritance and can be found in the homozygous, compound heterozygous, or in the digenic state. GnRHR expression extends beyond the pituitary gland, and is found in reproductive tissues such as ovaries, uterus, and prostate and non-reproductive tissues such as heart, muscles, liver and melanoma cells. This comprehensive review explores GnRHR's multifaceted role in human reproduction and its clinical implications for reproductive disorders.

Klinefelter syndrome presenting as metastatic bilateral breast cancer: missed diagnostic opportunities.

Klinefelter syndrome (KS) is the most common cause of primary hypogonadism in male patients; however, the diagnosis of KS is frequently delayed or missed. This delay can lead to undesirable outcomes for patients, especially considering that individuals with KS have a higher risk of developing specific malignancies, including breast cancer, non-Hodgkin's lymphoma and mediastinal germ cell tumours. We present a case of a male patient in his 60s, where the established diagnosis of metastatic bilateral breast cancer prompted us to investigate and subsequently confirm a diagnosis of KS. This case highlights the diagnostic challenges of KS and emphasises the unfavourable consequences of a delayed diagnosis. We aim to raise awareness and enhance physicians' understanding of KS and its non-reproductive manifestations, with a view to promote early recognition and improve patient outcomes.

The testicular microvasculature in Klinefelter syndrome is immature with compromised integrity and characterized by excessive inflammatory cross-talk.

STUDY QUESTION: Does Klinefelter syndrome (KS) lead to a distinct gene expression pattern at single-cell level in the testes that could provide insight into the reported microvascular dysfunction in the testes? SUMMARY ANSWER: A distinct gene expression pattern within microvascular-associated cells of males with KS suggests excessive endothelial cell (EC) activation, disorganized vessel formation, and the presence of immature vessels with compromised integrity. WHAT IS KNOWN ALREADY: Recent studies show that males with KS exhibit microvascular dysfunction in their testes, which affects blood flow and is associated with lower circulating levels of testosterone. STUDY DESIGN, SIZE, DURATION: A comparative cross-sectional study of males with KS (n = 6), non-obstructive azoospermia (NOA) (n = 5), cryptozoospermia (n = 3), and controls (n = 15) was carried out. PARTICIPANTS/MATERIALS, SETTING, METHODS: We analyzed publicly available single-cell RNA sequencing data of testicular cells from males with KS, males with NOA, males with cryptozoospermia, and controls. The integration of these datasets allowed us to analyze gene expression profiles and communication patterns among the cell types within the testis and to identify capillary ECs to investigate changes at the microvascular level. MAIN RESULTS AND THE ROLE OF CHANCE: Rooted in changes at the single-cell level, our study demonstrates a shift in gene expression forming the foundation for altered cellular communication, microvascular remodeling, and pro-inflammatory responses within the testes of males with KS. We identified genes that were dysregulated in capillary ECs from males with KS (Padj < 0.05). Specifically, the unique microvascular gene expression in males with KS indicated enhanced capillary EC activation and increased inflammatory cross-talk, leading to impaired vessel maturation and increased EC barrier permeability. LIMITATIONS, REASONS FOR CAUTION: Our study is constrained by an unbalanced design, with varying sample sizes and number of cells within each group. We acknowledge the restricted access to clinical information. In addition, our findings were deduced from changes in gene expression, which limits us to infer potential biological consequences arising from these alterations. Furthermore, the absence of a pre-pubertal age group limits the generalizability of our findings and warrants further investigation. WIDER IMPLICATIONS OF THE FINDINGS: This study offers novel insights into the testicular pathophysiology in KS and underscores the potential contribution of microvascular dysfunction to the hypogonadism and infertility observed in males with KS. While this study aims to better understand the microvascular dysfunction in KS, the precise connections to testosterone deficiency and testicular atrophy remain to be fully elucidated. STUDY FUNDING/COMPETING INTEREST(S): A.S. was supported by the Independent Research Fund Denmark (0134-00130B). C.H.G. was supported by Novo Nordisk Foundation (NNF15OC0016474, NNF20OC0060610), 'Fonden til lægevidenskabens fremme', the Familien Hede Nielsen foundation and the Independent Research Fund Denmark (0134-00406A). E.B.J. was supported by Aarhus University and E.B.J. and C.H.G by the Independent Research Fund Denmark (2096-00165A). J.M.K. was supported by Lundbeckfonden (R307-2018-3667), Carlsberg Fonden (CF19-0687), Novo Nordisk Fonden (0073440) and Steno Diabetes Center Aarhus (SDCA). The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.