Congenital Idiopathic Hypogonadotropic Hypogonadism Research Articles

A novel compound variant in GNRHR causing congenital idiopathic hypogonadotropic hypogonadism in a young male Korean patient.

Idiopathic hypogonadotropic hypogonadism (IHH) is a disease that shows symptoms of no or incomplete sexual maturation after 18 years old. The mutation of gonadotropin releasing hormone receptor gene (GNRHR) has been reported as the cause in 16% of total IHH patients. An 18-year-old adolescent was referred to endocrinology department for hypogonadism. He was born with cryptorchidism, had small testes at the age of 7 years, and showed low testosterone levels. Management of his hypogonadism was delayed due to his uncontrolled nephrotic syndrome. There were no abnormal findings on the brain MRI; atrophied testes discovered on his pelvis MRI; low levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were observed. In the HCG simulation test, testosterone levels showed no significant increase, rising from 1.11 to 1.15 ng/dL. The patient harbored a novel compound heterozygous variant of c.514G>A (p.Gly172Arg) and c.113G>A (p.Arg38Gln) in the GNRHR gene. Here, we report a case of new GNRHR compound variant c.514G>A (p.Gly172Arg) and c.113G>A (p.Arg38Gln) in a Korean adolescent for hypogonadotropic hypogonadism.

Reproductive endocrine phenotypes relating to CHD7 mutations in humans.

Mutations in the gene CHD7 cause CHARGE syndrome, a rare multi-organ syndromic disorder. Gonadal defects are common in individuals with CHARGE syndrome (seen in ∼60-80% of cases) and represent the letter "G" in the CHARGE syndrome acronym. The gonadal defect in CHARGE syndrome results from congenital deficiency of the hypothalamic hormone Gonadotropin-releasing hormone (GnRH), which manifests clinically as pubertal failure and infertility, and biochemically as hypogonadotropic hypogonadism (low sex steroid hormone levels with inappropriately normal or low gonadotropin levels). In addition to the gonadal endocrine abnormalities, in a small minority of individuals with CHARGE, additional endocrine defects including growth hormone deficiency, multiple pituitary hormone deficits and primary hypothyroidism may also be seen. CHD7 mutations disrupt the targeting of olfactory axons and the migration of GnRH-synthesizing neurons during embryonic development, resulting in congenital idiopathic hypogonadotropic hypogonadism (IHH) and anosmia (or hyposmia), two features that define human Kallmann syndrome. Since Kallmann syndrome is one of the constituent phenotypes within CHARGE, recent studies have investigated the role of CHD7 mutations in individuals with IHH and established that deleterious missense mutations in CHD7 are associated with Kallmann syndrome as well as normosmic form of IHH. These missense mutations affect the ATPase and nucleosome remodeling activities of the CHD7 protein. These observations suggest that CHD7 protein function is critical for the ontogeny of GnRH neurons and neuroendocrine regulation of GnRH secretion.

Kisspeptin Responsiveness Signals Emergence of Reproductive Endocrine Activity: Implications for Human Puberty

Some patients with idiopathic hypogonadotropic hypogonadism (IHH) undergo spontaneous activation of their hypothalamic-pituitary-gonadal axis resulting in normalization of steroidogenesis and/or gametogenesis, a phenomenon termed reversal. To assess the responsiveness of the GnRH neuronal network to exogenous kisspeptin administration in IHH patients who have undergone reversal. Six men with congenital IHH and evidence for reversal. Subjects underwent q10 min blood sampling to measure GnRH-induced LH secretion at baseline and in response to iv boluses of kisspeptin (0.24-2.4 nmol/kg) and GnRH (75 ng/kg). Individuals with sustained reversal of their hypogonadotropism (spontaneous LH pulses) responded to exogenous kisspeptin with a GnRH-induced LH pulse. Individuals who had reversal but then subsequently suffered relapse of their IHH (loss of spontaneous LH pulsatility) did not respond to kisspeptin. The ability of kisspeptin to stimulate a GnRH-induced LH pulse correlates with the presence of endogenous LH pulses. These data suggest that reversal of hypogonadotropism, and by extension sexual maturation, may be due to the acquisition of kisspeptin responsiveness.

Exogenous kisspeptin administration as a probe of GnRH neuronal function in patients with idiopathic hypogonadotropic hypogonadism.

Idiopathic hypogonadotropic hypogonadism (IHH) results from defective synthesis, secretion, or action of GnRH. Kisspeptin is a potent stimulus for GnRH secretion. We probed the functional capacity of the GnRH neuronal network in patients with IHH. Eleven subjects with congenital IHH (9 men and 2 women) and one male subject who underwent reversal of IHH were studied. Six of the twelve subjects had an identified genetic cause of their IHH: KAL1 (n = 1), FGFR1 (n = 3), PROKR2 (n = 1), GNRHR (n = 1). Subjects underwent q10 min blood sampling to measure GnRH-induced LH secretion at baseline and in response to intravenous boluses of kisspeptin (0.24 nmol/kg) and GnRH (75 ng/kg) both pre- and post-six days of treatment with exogenous GnRH (25 ng/kg sc every 2 h). All subjects with abiding IHH failed to demonstrate a GnRH-induced LH response to exogenous kisspeptin. In contrast, the subject who achieved reversal of his hypogonadotropism demonstrated a robust response to kisspeptin. The functional capacity of the GnRH neuronal network in IHH patients is impaired, as evidenced by their inability to respond to the same dose of kisspeptin that effects a robust GnRH-induced LH response in healthy men and luteal-phase women. This impairment is observed across a range of genotypes, suggesting that it reflects a fundamental property of GnRH neuronal networks that have not been properly engaged during pubertal development. In contrast, a patient who had experienced reversal of his hypogonadotropism responded to exogenous kisspeptin.

An Usual Case of Congenital Pulmonary Stenosis

Congenital idiopathic hypogonadotropic hypogonadism (IHH) is caused by the lack of production or physiological response to gonadotropin releasing hormone (GnRH). A wide variety of genetic mutations have been implicated in the disorder demonstrating autosomal dominant, recessive and X-linked inheritance patterns. Diagnosis of IHH is complicated by its similarity in presentation to a constitutional delay of puberty (CDP) and often goes undiagnosed in patients under the age of 18. Once IHH is identified, the effects of the disturbed HPA axis must be addressed. In this report, we offer a brief overview of the diagnosis and management of IHH and present the case of a 27 year old male with undiagnosed IHH.

Congenital Idiopathic Hypogonadotropic Hypogonadism: A Case Report

Congenital idiopathic hypogonadotropic hypogonadism (IHH) is caused by the lack of production or physiological response to gonadotropin releasing hormone (GnRH). A wide variety of genetic mutations have been implicated in the disorder demonstrating autosomal dominant, recessive and X-linked inheritance patterns. Diagnosis of IHH is complicated by its similarity in presentation to a constitutional delay of puberty (CDP) and often goes undiagnosed in patients under the age of 18. Once IHH is identified, the effects of the disturbed HPA axis must be addressed. In this report, we offer a brief overview of the diagnosis and management of IHH and present the case of a 27 year old male with undiagnosed IHH.

Deletion of Otx2 in GnRH Neurons Results in a Mouse Model of Hypogonadotropic Hypogonadism

GnRH is the central regulator of reproductive function responding to central nervous system cues to control gonadotropin synthesis and secretion. GnRH neurons originate in the olfactory placode and migrate to the forebrain, in which they are found in a scattered distribution. Congenital idiopathic hypogonadotropic hypogonadism (CIHH) has been associated with mutations or deletions in a number of genes that participate in the development of GnRH neurons and expression of GnRH. Despite the critical role of GnRH in mammalian reproduction, a comprehensive understanding of the developmental factors that are responsible for regulating the establishment of mature GnRH neurons and the expression of GnRH is lacking. orthodenticle homeobox 2 (OTX2), a homeodomain protein required for the formation of the forebrain, has been shown to be expressed in GnRH neurons, up-regulated during GnRH neuronal development, and responsible for increased GnRH promoter activity in GnRH neuronal cell lines. Interestingly, mutations in Otx2 have been associated with human hypogonadotropic hypogonadism, but the mechanism by which Otx2 mutations cause CIHH is unknown. Here we show that deletion of Otx2 in GnRH neurons results in a significant decrease in GnRH neurons in the hypothalamus, a delay in pubertal onset, abnormal estrous cyclicity, and infertility. Taken together, these data provide in vivo evidence that Otx2 is critical for GnRH expression and reproductive competence.

Congenital Idiopathic Hypogonadotropic Hypogonadism: Evidence of Defects in the Hypothalamus, Pituitary, and Testes

Idiopathic hypogonadotropic hypogonadism (IHH) with normal smell (normosmic IHH) or anosmia (Kallmann syndrome) is associated with defects in the production or action of GnRH. Accordingly, most IHH patients respond to physiological pulsatile GnRH replacement by normalizing serum LH, FSH, and testosterone (T) levels and achieving gametogenesis; some patients, however, show atypical responses. Interestingly, several IHH-associated genes are expressed in multiple compartments of the hypothalamic-pituitary-gonadal axis. The aim of the study was to investigate whether the clinical, biochemical, or genetic characteristics of IHH men with atypical responses to GnRH indicate alternative or additional defects in the hypothalamic-pituitary-gonadal axis. We studied 90 IHH men undergoing long-term pulsatile GnRH treatment over 30 yr. We conducted a retrospective study of response to GnRH at a Clinical Research Center. Physiological regimens of pulsatile s.c. GnRH were administered for at least 12 months. Dose-response studies using i.v. GnRH pulses assessed the pituitary LH response. We measured serum T, LH, FSH, and inhibin B levels, sperm in ejaculate, and determined the sequence of IHH-associated genes. Twenty-six percent of subjects displayed atypical responses to GnRH: 1) 10 remained hypogonadotropic and hypogonadal, demonstrating pituitary and testicular defects; 2) eight achieved spermatogenesis and normal T but only with hypergonadotropism, indicating impaired testicular responsiveness to gonadotropins; and 3) five remained azoospermic despite achieving adult testicular volumes and normal hormonal profiles, suggesting primary defects in spermatogenesis. Mutations were identified only in KAL1 across groups. In addition to hypothalamic GnRH deficiency, IHH men can have primary pituitary and/or testicular defects, which are unmasked by GnRH replacement.

Congenital Idiopathic Hypogonadotropic Hypogonadism: Evidence of Defects in the Hypothalamus, Pituitary, and Testes

Congenital Idiopathic Hypogonadotropic Hypogonadism: Evidence of Defects in the Hypothalamus, Pituitary, and Testes

Genetics of hypogonadotropic hypogonadism.

Determining the physiologic influences that modulate GnRH secretion, the prime initiator of reproductive function in the human, is fundamental not only to our understanding of the rare condition of congenital idiopathic hypogonadotropic hypogonadism (IHH), but also common disorders such as constitutional delay of puberty and hypothalamic amenorrhea. IHH is characterized by low levels of sex steroids and gonadotropins, normal findings on radiographic imaging of the hypothalamic-pituitary regions, and normal baseline and reserve testing of the remainder of the hypothalamic-pituitary axes. Failure of the normal pattern of episodic GnRH secretion results in delay of puberty and infertility. IHH is characterized by rich clinical and genetic heterogeneity, variable modes of inheritance, and association with other anomalies. To date, 4 genes have been identified as causes of IHH in the human; KAL [the gene for X-linked Kallmann syndrome (IHH and anosmia)], DAX1 [the gene for X-linked adrenal hypoplasia congenita (IHH and adrenal insufficiency)], GNRHR (the GnRH receptor), and PC1 (the gene for prohormone convertase 1, causing a syndrome of IHH and defects in prohormone processing). As these mutations account for less than 20% of all IHH cases, discovery of additional gene mutations will continue to advance our understanding of this intriguing syndrome.