Contribution of functionally assessed GHRHR mutations to idiopathic isolated growth hormone deficiency in patients without GH1 mutations.

Isolated growth hormone deficiency (IGHD) is a rare condition mainly caused by mutations in GH1. The aim of this study was to assess the contribution of GHRHR mutations to IGHD in an unusually large group of patients. All GHRHR coding exons and flanking intronic regions were sequenced in 312 unrelated patients with nonsyndromic IGHD. Functional consequences of all newly identified missense variants were assessed in vitro (i.e., study of the expression of recombinant GHRHRs and their ability to activate the cyclic adenosine monophosphate (cAMP) signaling pathway). Genotype-phenotype correlation analyses were performed according to the nature of the identified mutation. We identified 20 different disease-causing GHRHR mutations (truncating and missense loss-of-function mutations), among which 15 are novel, in 24 unrelated patients. Of note, about half (13/24) of those patients represent sporadic cases. The clinical phenotype of patients with at least one missense GHRHR mutation was found to be indistinguishable from that of patients with bi-allelic truncating mutations. This study, which unveils disease-causing GHRHR mutations in 8% (24/312) of IGHD cases, identifies GHRHR as the second IGHD gene most frequently involved after GH1. The finding that 8% of IGHD cases without GH1 mutations are explained by GHRHR molecular defects (including missense mutations), together with the high proportion of sporadic cases among those patients, has important implications for genetic counseling.

The Severity of Congenital Hypothyroidism With Gland-In-Situ Predicts Molecular Yield by Targeted Next-Generation Sequencing.

INTRODUCTION: Congenital hypothyroidism with gland-in-situ (CH-GIS) is usually attributed to mutations in the genes involved in thyroid hormone production. The diagnostic yield of targeted next-generation sequencing (NGS) varied widely between studies. We hypothesized that the molecular yield of targeted NGS would depend on the severity of CH. METHODS: Targeted NGS was performed in 103 CH-GIS patients from the French national screening program referred to the Reference Center for Rare Thyroid Diseases of Angers University Hospital. The custom targeted NGS panel contained 48 genes. Cases were classified as solved or probably solved depending on the known inheritance of the gene, the classification of the variants according to the American College of Medical Genetics and Genomics, the familial segregation, and published functional studies. Thyroid-stimulating hormone at CH screening and at diagnosis (TSHsc and TSHdg) and free T4 at diagnosis (FT4dg) were recorded. RESULTS: NGS identified 95 variants in 10 genes in 73 of the 103 patients, resulting in 25 solved cases and 18 probably solved cases. They were mainly due to mutations in the TG (n = 20) and TPO (n = 15) genes. The molecular yield was, respectively, 73% and 25% if TSHsc was ≥ and < 80 mUI/L, 60% and 30% if TSHdg was ≥ and < 100 mUI/L, and 69% and 29% if FT4dg was ≤ and > 5 pmol/L. CONCLUSION: NGS in patients with CH-GIS in France found a molecular explanation in 42% of the cases, increasing to 70% when TSHsc was ≥ 80 mUI/L or FT4dg was ≤ 5 pmol/L.

The insulin-like growth factor-I response to growth hormone is increased in prepubertal children with obesity and tall stature.

CONTEXT: Children with obesity [body mass index (BMI) > +2 sd score (SDS)] and children with constitutional tall stature [CTS; height > +2 SDS)] have normal-high serum IGF-I levels, associated with a low and broad range of GH secretion, respectively. This suggests increased sensitivity to GH, whereas children with idiopathic short stature (ISS; height < -2 SDS) are believed to have decreased GH sensitivity. OBJECTIVE, DESIGN, AND MAIN OUTCOME MEASURE: To compare the responsiveness to GH in 62 prepubertal children (43 females, 19 males) with obesity, CTS, or ISS and 26 controls (15 females, 11 males; height and BMI -2 to +2 SDS), we used an IGF-I generation test and studied the IGF-I concentration 24 h after a single injection of GH (2 mg/m2). PATIENTS: Twenty patients with obesity, 20 with CTS, 22 with ISS, and 26 controls were studied. The mean age was 8.3 +/- 2.9 yr, with no difference in age or gender between groups. RESULTS: Compared with controls, the mean IGF-I increment was 80% higher in obese children and 36% higher in tall children (P < 0.05 obese or tall vs. control children; P = 0.05 obese vs. tall children). Conversely, the IGF-I increment was similar in short compared with control children, despite a mean baseline IGF-I 62% lower in short children (P < 0.05 vs. controls). In all groups, the IGF-I increment was correlated with the BMI SDS or the fat mass percentage (r = 0.51-0.58, P < 0.05). CONCLUSION: Obese children tend to have greater GH responsiveness than tall children, and both have greater GH responsiveness than controls. GH responsiveness was similar in controls and short children, despite a lower baseline IGF-I in short children. Whether the differences in the IGF-I response to GH between these children reflect differences in the respective anabolic (growth promotion) and metabolic (i.e. insulin action modulation) roles of circulating IGF-I is unknown.

Novel compound heterozygous Thyroglobulin mutations c.745+1G>A/c.7036+2T>A associated with congenital goiter and hypothyroidism in a Vietnamese family. Identification of a new cryptic 5' splice site in the exon 6.

Several patients were identified with dyshormonogenesis caused by mutations in the thyroglobulin (TG) gene. These defects are inherited in an autosomal recessive manner and affected individuals are either homozygous or compound heterozygous for the mutations. The aim of the present study was to identify new TG mutations in a patient of Vietnamese origin affected by congenital hypothyroidism, goiter and low levels of serum TG. DNA sequencing identified the presence of compound heterozygous mutations in the TG gene: the maternal mutation consists of a novel c.745+1G>A (g.IVS6 + 1G>A), whereas the hypothetical paternal mutation consists of a novel c.7036+2T>A (g.IVS40 + 2T>A). The father was not available for segregation analysis. Ex-vivo splicing assays and subsequent RT-PCR analyses were performed on mRNA isolated from the eukaryotic-cells transfected with normal and mutant expression vectors. Minigene analysis of the c.745+1G>A mutant showed that the exon 6 is skipped during pre-mRNA splicing or partially included by use of a cryptic 5' splice site located to 55 nucleotides upstream of the authentic exon 6/intron 6 junction site. The functional analysis of c.7036+2T>A mutation showed a complete skipping of exon 40. The theoretical consequences of splice site mutations, predicted with the bioinformatics tool NNSplice, Fsplice, SPL, SPLM and MaxEntScan programs were investigated and evaluated in relation with the experimental evidence. These analyses predicted that both mutant alleles would result in the abolition of the authentic splice donor sites. The c.745+1G>A mutation originates two putative truncated proteins of 200 and 1142 amino acids, whereas c.7036+2T>A mutation results in a putative truncated protein of 2277 amino acids. In conclusion, we show that the c.745+1G>A mutation promotes the activation of a new cryptic donor splice site in the exon 6 of the TG gene. The functional consequences of these mutations could be structural changes in the protein molecule that alter the biosynthesis of thyroid hormones.

Divergent effect of endogenous and exogenous sex steroids on the insulin-like growth factor I response to growth hormone in short normal adolescents.

The lower responsiveness to GH in women than in men is probably due to a divergent effect of gonadal steroids. It is unknown, however, how the progressive increase in sex steroid production that occurs during puberty affects this responsiveness. To compare the effects of puberty and sex steroid administration on responsiveness to GH, we used the IGF-I generation test, in which the peak IGF-I level 24 h after a single injection of GH (2 mg/m2) was studied in 117 healthy short subjects (56 females and 61 males). The subjects, aged 8-16 yr, were divided into four groups: prepuberty, early puberty, midpuberty, or pubertal delay. In the latter group, the IGF-I response was determined before and after priming with oral 17beta-estradiol in girls and im testosterone in boys. We also tested for an association between body composition (by dual energy x-ray absorptiometry) and the IGF-I response to GH. The IGF-I increment in response to GH (change in IGF-I from baseline) was correlated with the growth velocity sd score (P < 0.05). Progression throughout puberty was associated with an increase in both baseline IGF-I (P < 0.05) and the IGF-I increment in response to GH (P < 0.05), with no gender difference. Pubertal category (pre-, early, and midpuberty; P < 0.05) and fat percentage (P < 0.05) were the main positive predictors of the IGF-I increment in response to GH, expressed as micrograms per liter as well as sd score, independently of baseline IGF-I. After sex steroid priming, both the GH peak in response to insulin-induced hypoglycemia and baseline IGF-I were increased (P < 0.05, after vs. before sex steroid). However, the IGF-I increment in response to GH decreased after oral 17beta-estradiol (P < 0.05), whereas it was unchanged after testosterone administration. Endogenous gonadal steroid secretion appears to result in increased responsiveness to GH in peripubertal girls and boys. By contrast, exogenous estrogen and testosterone, respectively, produce a relative decrease and no change in responsiveness to GH in similar populations, possibly through the achievement of sex steroid concentrations exceeding physiological ranges for age. Fat percentage was a positive determinant of the responsiveness to GH, suggesting a link between the energy stores and the anabolic action of GH.

Impaired aerobic exercise adaptation in children and adolescents with craniopharyngioma is associated with hypothalamic involvement.

OBJECTIVE: Many patients treated for craniopharyngioma (CP) complain of a relative incapacity for physical activity. Whether this is due to an objective decrease in adaptation to exercise is unclear. We assessed exercise tolerance in children with surgically treated CP and appropriate pituitary hormone replacement therapy compared with healthy controls and we examined the potential relationships with hypothalamic involvement, GH replacement, and the catecholamine deficiency frequently observed in these subjects. DESIGN AND METHODS: Seventeen subjects (12 males and five females) with CP and 22 healthy controls (14 males and eight females) aged 15.3±2.5 years (7.3-18 years) underwent a standardized cycle ergometer test. Maximum aerobic capacity was expressed as the ratio of VO(2max) to fat-free mass (VO(2max)/FFM), a measure independent of age and fat mass in children. RESULTS: VO(2max)/FFM was 20% lower in children with CP compared with controls (P<0.05), even after adjustment for gender. Children with hypothalamic involvement (n=10) had a higher percentage of fat mass (P<0.05) than those without hypothalamic involvement (n=7) and lower VO(2max)/FFM (P<0.05), whereas children without hypothalamic involvement had VO(2max)/FFM close to that of controls (P>0.05). GH treatment was associated with a significant positive effect on aerobic capacity (P<0.05) only in the absence of hypothalamic involvement. No relationship was found between exercise capacity parameters and daily urine epinephrine excretion or epinephrine peak response to insulin-induced hypoglycemia. CONCLUSIONS: Children with CP have a decrease in aerobic capacity mainly related to hypothalamic involvement. The hypothalamic factors altering aerobic capacity remain to be determined.

Genomic imbalances detected by array-CGH in patients with syndromal ocular developmental anomalies.

In 65 patients, who had unexplained ocular developmental anomalies (ODAs) with at least one other birth defect and/or intellectual disability, we performed oligonucleotide comparative genome hybridisation-based microarray analysis (array-CGH; 105A or 180K, Agilent Technologies). In four patients, array-CGH identified clinically relevant deletions encompassing a gene known to be involved in ocular development (FOXC1 or OTX2). In four other patients, we found three pathogenic deletions not classically associated with abnormal ocular morphogenesis, namely, del(17)(p13.3p13.3), del(10)(p14p15.3), and del(16)(p11.2p11.2). We also detected copy number variations of uncertain pathogenicity in two other patients. Rearranged segments ranged in size from 0.04 to 5.68 Mb. These results show that array-CGH provides a high diagnostic yield (15%) in patients with syndromal ODAs and can identify previously unknown chromosomal regions associated with these conditions. In addition to their importance for diagnosis and genetic counselling, these data may help identify genes involved in ocular development.

Baseline inhibin B and anti-Mullerian hormone measurements for diagnosis of hypogonadotropic hypogonadism (HH) in boys with delayed puberty.

CONTEXT: The diagnosis of isolated hypogonadotropic hypogonadism (IHH) in boys with delayed puberty is challenging, as may be the diagnosis of hypogonadotropic hypogonadism (HH) in boys with combined pituitary hormone deficiency (CPHD). Yet, the therapeutic choices for puberty induction depend on accurate diagnosis and may influence future fertility. OBJECTIVE: The aim was to assess the utility of baseline inhibin B (INHB) and anti-Mullerian hormone (AMH) measurements to discriminate HH from constitutional delay of puberty (CDP). Both hormones are produced by Sertoli cells upon FSH stimulation. Moreover, prepubertal AMH levels are high as a reflection of Sertoli cell integrity. PATIENTS: We studied 82 boys aged 14 to 18 yr with pubertal delay: 16 had IHH, 15 congenital HH within CPHD, and 51 CDP, as confirmed by follow-up. Subjects were genital stage 1 (testis volume<3 ml; 9 IHH, 7 CPHD, and 23 CDP) or early stage 2 (testis volume, 3-6 ml; 7 IHH, 8 CPHD, and 28 CDP). RESULTS: Age and testis volume were similar in the three groups. Compared with CDP subjects, IHH and CPHD subjects had lower INHB, testosterone, FSH, and LH concentrations (P<0.05), whereas AMH concentration was lower only in IHH and CPHD subjects with genital stage 1, likely reflecting a smaller pool of Sertoli cells in profound HH. In IHH and CPHD boys with genital stage 1, sensitivity and specificity were 100% for INHB concentration of 35 pg/ml or less. In IHH and CPHD boys with genital stage 2, sensitivities were 86 and 80%, whereas specificities were 92% and 88%, respectively, for an INHB concentration of 65 pg/ml or less. The performance of testosterone, AMH, FSH, and LH measurements was lower. No combination or ratio of hormones performed better than INHB alone. CONCLUSION: Discrimination of HH from CDP with baseline INHB measurement was excellent in subjects with genital stage 1 and fair in subjects with genital stage 2.

High birth weight and early postnatal weight gain protect obese children and adolescents from truncal adiposity and insulin resistance: metabolically healthy but obese subjects?

OBJECTIVE: Low birth weight (LBW), no early catch-up weight, and subsequent fat accumulation have been associated with increased risks of insulin resistance from childhood onward and later cardiovascular disease. We sought to clarify the effects of high birth weight (HBW) and postnatal weight gain on insulin resistance. RESEARCH DESIGN AND METHODS: A total of 117 obese children aged 10.4 +/- 2.4 years were divided into three groups according to fetal growth after exclusion of maternal diabetes. They were comparable for age, sex, puberty, and percent body fat. Customized French birth weight standards, adjusted for maternal characteristics and gestation number, identified subjects with true altered fetal growth: 32 had increased fetal growth according to customized standards (HBWcust), 52 were eutrophic, and 33 had restricted fetal growth according to customized standards (LBWcust). Fat distribution by dual-energy X-ray absorptiometry, insulin sensitivity indexes from an oral glucose tolerance test (OGTT), and leptin, adiponectin, and visfatin levels were compared between groups. RESULTS: The HBWcust subjects had a higher adiponectin level, higher whole-body insulin sensitivity index (WBISI), and lower hepatic insulin resistance index, lower insulin and free fatty acid concentrations during OGTT, and lower trunk fat percent than eutrophic (P < 0.05) and LBWcust subjects (P < 0.05). Besides birth weight, weight gain between 0 and 2 years was a positive predictor (P < 0.05) of WBISI, whereas weight gain after 4 years was a negative predictor (P < 0.05). CONCLUSIONS: HBW and early weight gain may program insulin sensitivity and adipose tissue metabolism and contribute to so-called metabolically healthy obesity.

Effect of single and multiple courses of prenatal corticosteroids on 17-hydroxyprogesterone levels: implication for neonatal screening of congenital adrenal hyperplasia.

Measurement of 17-hydroxyprogesterone (17-OHP) from filter-paper blood is widely used to screen for congenital adrenal hyperplasia (CAH). However, in pregnancies with an expected preterm delivery, prenatal treatment with steroids to induce pulmonary maturation could suppress the fetal adrenals and interfere with this screening. In 160 infants who were born between 25 and 35 wk of gestation, we measured 17-OHP in filter-paper blood at 72-96 h and compared the values between those who had not received antenatal steroids (n=50) and those who had (n=110). A single course of steroids was two 12-mg injections of betamethasone given within a 24-h interval: 30 infants received a half single course, 45 received a full single course, and 35 received multiple courses. Results are expressed as medians (25th percentile; 75th percentile). Blood 17-OHP differed significantly among groups: 23.7 (14.2; 30.7) nmol/L, 26.1 (15.0; 50.1) nmol/L, 20.1 (13.8; 29.1) nmol/L, and 14.9 (9.5; 26.2) nmol/L (for, respectively, no steroid, half a single course, a full single course, and multiple courses; p <0.05, multiple comparisons with the Kruskal-Wallis test). However, only infants who were treated with multiple antenatal courses of steroids had lower blood 17-OHP than those who were untreated (p <0.05 with the Mann-Whitney U test). In multiple regression analysis, steroid treatment and intrauterine growth retardation were significant negative predictors of blood 17-OHP, whereas respiratory distress syndrome was a significant positive predictor (multiple R=0.50, p <0.001). Multiple courses of steroids in preterm infants decrease 17-OHP values by approximately 30% in filter-paper blood, thus raising the risk of false-negative results in screening programs for CAH.