Neuroendocrine, gonadal, placental, and obstetric phenotypes in patients with IHH and mutations in the G-protein coupled receptor, GPR54.

The G protein coupled receptor, GPR54, is a key regulator of puberty and reproductive function. Despite its prismatic role, few patients with mutations in GPR54 and the phenotype of hypogonadotropic hypogonadism have been described. This report explores the neuroendocrine, gonadal, placental and obstetric phenotypes of patients with idiopathic hypogonadotropic hypogonadism (IHH) carrying missense (L148S), nonsense (R331X), and nonstop (X399R) mutations in GPR54. A male patient harboring the mutations R331X and X399R demonstrated (1) increased sensitivity to exogenous pulsatile GnRH compared to a cohort of IHH patients undergoing similar therapy and (2) steady increases in testicular volume, spermatogenesis, and fertility while on long-term GnRH therapy. A female patient homozygous for the L148S mutation had (1) intact responses to exogenous GnRH and gonadotropins, (2) multiple conceptions, (3) two uncomplicated pregnancies of healthy children, suggesting grossly intact placental function, (4) spontaneous initiation of uterine contractions, and (5) lactation for several months post-partum. Taken together, these observations help to tease apart the neuroendocrine and gonadal phenotypes of patients bearing mutations in GPR54.

Long-term effects of a ketogenic diet in obese patients.

BACKGROUND: Although various studies have examined the short-term effects of a ketogenic diet in reducing weight in obese patients, its long-term effects on various physical and biochemical parameters are not known. OBJECTIVE: To determine the effects of a 24-week ketogenic diet (consisting of 30 g carbohydrate, 1 g/kg body weight protein, 20% saturated fat, and 80% polyunsaturated and monounsaturated fat) in obese patients. PATIENTS AND METHODS: In the present study, 83 obese patients (39 men and 44 women) with a body mass index greater than 35 kg/m(2), and high glucose and cholesterol levels were selected. The body weight, body mass index, total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides, fasting blood sugar, urea and creatinine levels were determined before and after the administration of the ketogenic diet. Changes in these parameters were monitored after eight, 16 and 24 weeks of treatment. RESULTS: The weight and body mass index of the patients decreased significantly (P<0.0001). The level of total cholesterol decreased from week 1 to week 24. HDL cholesterol levels significantly increased, whereas LDL cholesterol levels significantly decreased after treatment. The level of triglycerides decreased significantly following 24 weeks of treatment. The level of blood glucose significantly decreased. The changes in the level of urea and creatinine were not statistically significant. CONCLUSIONS: The present study shows the beneficial effects of a long-term ketogenic diet. It significantly reduced the body weight and body mass index of the patients. Furthermore, it decreased the level of triglycerides, LDL cholesterol and blood glucose, and increased the level of HDL cholesterol. Administering a ketogenic diet for a relatively longer period of time did not produce any significant side effects in the patients. Therefore, the present study confirms that it is safe to use a ketogenic diet for a longer period of time than previously demonstrated.

The GPR54 gene as a regulator of puberty.

BACKGROUND: Puberty, a complex biologic process involving sexual development, accelerated linear growth, and adrenal maturation, is initiated when gonadotropin-releasing hormone begins to be secreted by the hypothalamus. We conducted studies in humans and mice to identify the genetic factors that determine the onset of puberty. METHODS: We used complementary genetic approaches in humans and in mice. A consanguineous family with members who lacked pubertal development (idiopathic hypogonadotropic hypogonadism) was examined for mutations in a candidate gene, GPR54, which encodes a G protein-coupled receptor. Functional differences between wild-type and mutant GPR54 were examined in vitro. In parallel, a Gpr54-deficient mouse model was created and phenotyped. Responsiveness to exogenous gonadotropin-releasing hormone was assessed in both the humans and the mice. RESULTS: Affected patients in the index pedigree were homozygous for an L148S mutation in GPR54, and an unrelated proband with idiopathic hypogonadotropic hypogonadism was determined to have two separate mutations, R331X and X399R. The in vitro transfection of COS-7 cells with mutant constructs demonstrated a significantly decreased accumulation of inositol phosphate. The patient carrying the compound heterozygous mutations (R331X and X399R) had attenuated secretion of endogenous gonadotropin-releasing hormone and a left-shifted dose-response curve for gonadotropin-releasing hormone as compared with six patients who had idiopathic hypogonadotropic hypogonadism without GPR54 mutations. The Gpr54-deficient mice had isolated hypogonadotropic hypogonadism (small testes in male mice and a delay in vaginal opening and an absence of follicular maturation in female mice), but they showed responsiveness to both exogenous gonadotropins and gonadotropin-releasing hormone and had normal levels of gonadotropin-releasing hormone in the hypothalamus. CONCLUSIONS: Mutations in GPR54, a G protein-coupled receptor gene, cause autosomal recessive idiopathic hypogonadotropic hypogonadism in humans and mice, suggesting that this receptor is essential for normal gonadotropin-releasing hormone physiology and for puberty.

Autosomal recessive idiopathic hypogonadotropic hypogonadism: genetic analysis excludes mutations in the gonadotropin-releasing hormone (GnRH) and GnRH receptor genes.

Failure of the normal pattern of episodic secretion of GnRH from the hypothalamus results in the clinical syndrome of idiopathic hypogonadotropic hypogonadism (IHH), with failure of pubertal development and infertility. The only gene that has been implicated in normosmic IHH is the GnRH receptor gene (GNRHR), which accounts for 10% of cases. This report presents four families with autosomal recessive IHH, including a consanguineous pedigree from the Middle East. Defects within the genomic coding sequence of the GNRHR, and the GnRH gene itself, GNRH1, were excluded by temperature gradient gel electrophoresis, direct sequencing, and haplotypes created from simple sequence polymorphisms flanking the GNRH1 and GNRHR loci. We concluded that: 1) genetic analysis has excluded sequence variations in GNRH1 and GNRHR in four families with recessive IHH, suggesting the existence of a novel, as-yet-undiscovered gene for this condition, and 2) because mutation analysis of genomic coding sequence will fail to detect mutations deep within introns or regulatory regions, haplotype analysis is the preferred genetic methodology to eliminate the role of specific candidate genes.

A locus for autosomal recessive idiopathic hypogonadotropic hypogonadism on chromosome 19p13.3.

Idiopathic hypogonadotropic hypogonadism (IHH) is traditionally established by 1) the absence of spontaneous pubertal development by age 18 yr and 2) low sex steroids with inappropriately low gonadotropins in the absence of any functional or anatomic cause. To identify a novel disease locus for IHH, a genome wide scan was performed on a large, consanguineous Saudi family with 6 affected individuals. Linkage over a 1.06 Mb interval on chromosome 19p13.3 was established with a maximal two point LOD score of 5.17. Because numerous genes and hypothetical proteins are mapped to this region, further studies will be necessary to determine the precise genetic defect in this family.

Negative feedback effects of gonadal steroids are preserved with aging in postmenopausal women.

There is now evidence for alterations in the neuroendocrine control of the reproductive axis with aging, but its sensitivity to gonadal steroid negative feedback remains controversial. To examine the independent effect of age and gonadal steroid negative feedback, younger (45-55 yr; n = 7) and older (70-80 yr; n = 6) postmenopausal women (PMW) were studied at baseline on no HRT, after 1 month of transdermal estrogen (50 microg/d; E) and again after a further month of E and 7 d of transvaginal progesterone (P) (100 mg bid; E + P). At each admission, blood was sampled every 5 min for 8 h for measurement of gonadotropin free alpha-subunit (FAS), which was used as a marker of GnRH pulse frequency. LH and FSH were measured in pooled samples. Midfollicular and midluteal phase levels of E2 and P were achieved during the E and E + P treatments and were not different between younger and older PMW. There was a negative feedback effect of E and E + P on mean LH (P < 0.0001) and an additional effect of age (P < 0.003), with older women having lower values throughout. Mean FSH was also decreased with E and E + P (P < 0.0001) and was consistently lower in the older women (P < 0.05). Mean FAS levels decreased with hormonal treatment (P < 0.0001) and age (P < 0.001), but the effect of hormonal treatment was attenuated in the older group (P < 0.005). FAS pulse frequency was unchanged with addition of E, but dramatically decreased with E + P (P < 0.002). Both hormonal replacement (P < 0.05) and age (P < 0.005) decreased FAS pulse amplitude, an effect that was attributable entirely to E as there was no additional change with E + P. These studies indicate that: 1) both age and gonadal steroids independently decrease mean LH, FSH, and FAS in PMW; 2) responsiveness to steroid negative feedback on FAS is attenuated with aging in absolute but not relative terms, whereas the effect on mean levels of LH and FSH is clearly preserved; and 3) FAS pulse frequency is unchanged with E2 administration but decreases dramatically with addition of P in both old and young PMW.