Central precocious puberty results from the premature activation of the hypothalamic-pituitary-gonadal axis. It mimics physiological pubertal development, although at an inappropriate chronological ...age (before 8 years in girls and 9 years in boys). It can be attributable to cerebral congenital malformations or acquired insults, but the cause in most cases in girls remains unknown. MKRN3 gene defects have been identified in familial disease, with important basic and clinical results. Indeed, genetic analysis of this gene should be included in the routine clinical investigation of familial and idiopathic cases of central precocious puberty. Gonadotropin-releasing hormone agonists are the gold-standard treatment. The assessment and management of this disease remain challenging for paediatric endocrinologists. In this Series paper, we describe current challenges involving the precise diagnosis and adequate treatment of this disorder.
Abstract
The etiology of central precocious puberty (CPP) is multiple and heterogeneous, including congenital and acquired causes that can be associated with structural or functional brain ...alterations. All causes of CPP culminate in the premature pulsatile secretion of hypothalamic GnRH and, consequently, in the premature reactivation of hypothalamic-pituitary-gonadal axis. The activation of excitatory factors or suppression of inhibitory factors during childhood represent the 2 major mechanisms of CPP, revealing a delicate balance of these opposing neuronal pathways. Hypothalamic hamartoma (HH) is the most well-known congenital cause of CPP with central nervous system abnormalities. Several mechanisms by which hamartoma causes CPP have been proposed, including an anatomical connection to the anterior hypothalamus, autonomous neuroendocrine activity in GnRH neurons, trophic factors secreted by HH, and mechanical pressure applied to the hypothalamus. The importance of genetic and/or epigenetic factors in the underlying mechanisms of CPP has grown significantly in the last decade, as demonstrated by the evidence of genetic abnormalities in hypothalamic structural lesions (eg, hamartomas, gliomas), syndromic disorders associated with CPP (Temple, Prader-Willi, Silver-Russell, and Rett syndromes), and isolated CPP from monogenic defects (MKRN3 and DLK1 loss-of-function mutations). Genetic and epigenetic discoveries involving the etiology of CPP have had influence on the diagnosis and familial counseling providing bases for potential prevention of premature sexual development and new treatment targets in the future. Global preventive actions inducing healthy lifestyle habits and less exposure to endocrine-disrupting chemicals during the lifespan are desirable because they are potentially associated with CPP.
Graphical Abstract
Congenital and acquired mechanisms implicated in the etiology of central precocious puberty. ARC, arcuate nucleus; AVPV, anteroventral periventricular nucleus; GABA, gamma-aminobutyric acid; ME, median eminence; MnPO, median preoptic nucleus; PMV, ventral premammillary nucleus; POA, preoptic area; OPG: optic pathways glioma.
Little is known about genetic control of the timing of puberty. This study implicates an imprinted gene,
MKRN3,
in familial central precocious puberty. The data suggest that the encoded protein ...inhibits puberty.
The onset of puberty is first detected as an increase in the amplitude and frequency of pulses of gonadotropin-releasing hormone (GnRH) after a quiescent period during childhood. The reemergence of pulsatile GnRH secretion leads to increases in the secretion of the gonadotropins, luteinizing hormone and follicle-stimulating hormone (FSH), by the pituitary gland and the consequent activation of gonadal function.
1
Early activation of the hypothalamic–pituitary–gonadal axis results in gonadotropin-dependent precocious puberty, also known as central precocious puberty, which is clinically defined by the development of secondary sexual characteristics before the age of 8 years in girls and 9 years in boys. . . .
The identification of loss-of-function mutations in MKRN3 in patients with central precocious puberty in association with the decrease in MKRN3 expression in the medial basal hypothalamus of mice ...before the initiation of reproductive maturation suggests that MKRN3 is acting as a brake on gonadotropin-releasing hormone (GnRH) secretion during childhood. In the current study, we investigated the mechanism by which MKRN3 prevents premature manifestation of the pubertal process. We showed that, as in mice, MKRN3 expression is high in the hypothalamus of rats and nonhuman primates early in life, decreases as puberty approaches, and is independent of sex steroid hormones. We demonstrated that Mkrn3 is expressed in Kiss1 neurons of the mouse hypothalamic arcuate nucleus and that MKRN3 repressed promoter activity of human KISS1 and TAC3, 2 key stimulators of GnRH secretion. We further showed that MKRN3 has ubiquitinase activity, that this activity is reduced by MKRN3 mutations affecting the RING finger domain, and that these mutations compromised the ability of MKRN3 to repress KISS1 and TAC3 promoter activity. These results indicate that MKRN3 acts to prevent puberty initiation, at least in part, by repressing KISS1 and TAC3 transcription and that this action may involve an MKRN3-directed ubiquitination-mediated mechanism.
Abstract
Context
Coronavirus disease 2019 (COVID-19) is a proinflammatory and prothrombotic condition, but its impact on adrenal function has not been adequately evaluated.
Case report
A 46-year-old ...woman presented with abdominal pain, hypotension, and skin hyperpigmentation after COVID-19 infection. The patient had hyponatremia, serum cortisol <1.0 µg/dL, adrenocorticotropin (ACTH) of 807 pg/mL, and aldosterone <3 ng/dL. Computed tomography (CT) findings of adrenal enlargement with no parenchymal and minimal peripheral capsular enhancement after contrast were consistent with bilateral adrenal infarction. The patient had autoimmune hepatitis and positive antiphospholipid antibodies, but no previous thrombotic events. The patient was treated with intravenous hydrocortisone, followed by oral hydrocortisone and fludrocortisone.
Discussion
We identified 9 articles, including case reports, of new-onset adrenal insufficiency and/or adrenal hemorrhage/infarction on CT in COVID-19. Adrenal insufficiency was hormonally diagnosed in 5 cases, but ACTH levels were measured in only 3 cases (high in 1 case and normal/low in other 2 cases). Bilateral adrenal nonhemorrhagic or hemorrhagic infarction was identified in 5 reports (2 had adrenal insufficiency, 2 had normal cortisol levels, and 1 case had no data). Interestingly, the only case with well-characterized new-onset acute primary adrenal insufficiency after COVID-19 had a previous diagnosis of antiphospholipid syndrome. In our case, antiphospholipid syndrome diagnosis was established only after the adrenal infarction triggered by COVID-19.
Conclusion
Our findings support the association between bilateral adrenal infarction and antiphospholipid syndrome triggered by COVID-19. Therefore, patients with positive antiphospholipid antibodies should be closely monitored for symptoms or signs of acute adrenal insufficiency during COVID-19.
Pubertal timing is influenced by complex interactions among genetic, nutritional, environmental, and socioeconomic factors. The role of MKRN3, an imprinted gene located in the Prader–Willi syndrome ...critical region (chromosome 15q11–13), in pubertal initiation was first described in 2013 after the identification of deleterious MKRN3 mutations in five families with central precocious puberty (CPP) using whole-exome sequencing analysis. Since then, additional loss-of-function mutations of MKRN3 have been associated with the inherited premature sexual development phenotype in girls and boys from different ethnic groups. In all of these families, segregation analysis clearly demonstrated autosomal dominant inheritance with complete penetrance, but with exclusive paternal transmission, consistent with the monoallelic expression of MKRN3 (a maternally imprinted gene). Interestingly, the hypothalamic Mkrn3 mRNA expression pattern in mice correlated with a putative inhibitory input on puberty initiation. Indeed, the initiation of puberty depends on a decrease in factors that inhibit the release of GnRH combined with an increase in stimulatory factors. These recent human and animal findings suggest that MKRN3 plays an inhibitory role in the reproductive axis to represent a new pathway in pubertal regulation.
Context Congenital hypogonadotropic hypogonadism (CHH) is a rare condition caused by GnRH deficiency. Several genes have been associated with the pathogenesis of CHH, but most cases still remain ...without a molecular diagnosis. The advent of next-generation sequencing (NGS) has allowed the simultaneous genotyping of several regions, faster, making possible the extension of the genetic knowledge of CHH. Objective Genetic characterization of a large cohort of Brazilian CHH patients. Design and patients A cohort of 130 unrelated patients (91 males, 39 females) with CHH (75 normosmic CHH, 55 Kallmann syndrome) was studied using a panel containing 36 CHH-associated genes. Results Potential pathogenic or probably pathogenic variants were identified in 43 (33%) CHH patients. The genes ANOS1, FGFR1 and GNRHR were the most frequently affected. A novel homozygous splice site mutation was identified in the GNRH1 gene and a deletion of the entire coding sequence was identified in SOX10. Deleterious variants in the IGSF10 gene were identified in two patients with reversible normosmic CHH. Notably, 6.9% of the patients had rare variants in more than one gene. Rare variants were also identified in SPRY4, IL17RD, FGF17, IGSF1 and FLRT3 genes. Conclusions This is a large study of the molecular genetics of CHH providing new genetic findings for this complex and heterogeneous genetic condition. NGS has been shown to be a fast, reliable and effective tool in the molecular diagnosis of congenital CHH and being able to targeting clinical genetic testing in the future.
Abstract
Context
Primary aldosteronism (PA) is the most common cause of endocrine hypertension (HT). HT remission (defined as blood pressure <140/90 mm Hg without antihypertensive drugs) has been ...reported in approximately 50% of patients with unilateral PA after adrenalectomy. HT duration and severity are predictors of blood pressure response, but the prognostic role of somatic KCNJ5 mutations is unclear.
Objective
To determine clinical and molecular features associated with HT remission after adrenalectomy in patients with unilateral PA.
Methods
We retrospectively evaluated 100 patients with PA (60 women; median age at diagnosis 48 years with a median follow-up of 26 months). Anatomopathological analysis revealed 90 aldosterone-producing adenomas, 1 carcinoma, and 9 unilateral adrenal hyperplasias. All patients had biochemical cure after unilateral adrenalectomy. KCNJ5 gene was sequenced in 76 cases.
Results
KCNJ5 mutations were identified in 33 of 76 (43.4%) tumors: p.Gly151Arg (n = 17), p.Leu168Arg (n = 15), and p.Glu145Gln (n = 1). HT remission was reported in 37 of 100 (37%) patients. Among patients with HT remission, 73% were women (P = 0.04), 48.6% used more than three antihypertensive medications (P = 0.0001), and 64.9% had HT duration <10 years (P = 0.0015) compared with those without HT remission. Somatic KCNJ5 mutations were associated with female sex (P = 0.004), larger nodules (P = 0.001), and HT remission (P = 0.0001). In multivariate analysis, only a somatic KCNJ5 mutation was an independent predictor of HT remission after adrenalectomy (P = 0.004).
Conclusion
The presence of a KCNJ5 somatic mutation is an independent predictor of HT remission after unilateral adrenalectomy in patients with unilateral PA.
The impact of KCNJ5 somatic mutations on hypertension remission after adrenalectomy brings new insight into the postoperative follow-up of patients with PA.
Precision medicine employs digital tools and knowledge of a patient’s genetic makeup, environment and lifestyle to improve diagnostic accuracy and to develop individualised treatment and prevention ...strategies. Precision medicine has improved management in a number of disease areas, most notably in oncology, and it has the potential to positively impact others, including endocrine disorders. The accuracy of diagnosis in young patients with growth disorders can be improved by using biomarkers. Insulin-like growth factor I (IGF-I) is the most widely accepted biomarker of growth hormone secretion, but its predictive value for recombinant human growth hormone treatment response is modest and various factors can affect the accuracy of IGF-I measurements. These factors need to be taken into account when considering IGF-I as a component of precision medicine in the management of growth hormone deficiency. The use of genetic analyses can assist with diagnosis by confirming the aetiology, facilitate treatment decisions, guide counselling and allow prompt intervention in children with pubertal disorders, such as central precocious puberty and testotoxicosis. Precision medicine has also proven useful during the transition of young people with endocrine disorders from paediatric to adult services when patients are at heightened risk of dropping out from medical care. An understanding of the likelihood of ongoing GH deficiency, using tools such as MRI, detailed patient history and IGF-I levels, can assist in determining the need for continued recombinant human growth hormone treatment during the process of transitional care.
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