Genetic disorders of GH action pathway

Insulin-like growth factor 1 (IGF-1) is an anabolic hormone with several biological activities, such as proliferation, mitochondrial protection, cell survival, tissue growth and development, anti-inflammatory, antioxidant, antifibrogenic and antiaging. This hormone plays an important role in embryological and postnatal states, being essential for normal foetal and placental growth and differentiation. During gestation, the placenta is one of the major sources of IGF-1, among other hormones. This intrauterine organ expresses IGF-1 receptors and IGF-1 binding proteins (IGFBPs), which control IGF-1 activities. Intrauterine growth restriction (IUGR) is the second most frequent cause of perinatal morbidity and mortality, defined as the inability to achieve the expected weight for gestational age. Different studies have revealed that IUGR infants have placental dysfunction and low circulating levels of insulin, IGF-1, IGF-2 and IGFBPs. Such data suggest that IGF-1 deficiency in gestational state may be one of the major causes of foetal growth retardation. The aim of this review is to study the epidemiology, physiopathology and possible causes of IUGR. Also, it intends to study the possible role of the placenta as an IGF-1 target organ. The purpose is to establish if IUGR could be considered as a novel condition of IGF-1 deficiency and if its treatment with low doses of IGF-1 could be a suitable therapeutic strategy.

New England Journal of Medicine, 2003

Approximately 10 percent of infants with intrauterine growth retardation remain small, and the causes of their growth deficits are often unclear. We postulated that mutations in the gene for the insulin-like growth factor I receptor (IGF-IR) might underlie some cases of prenatal and postnatal growth failure. methods We screened two groups of children for abnormalities in the IGF-IR gene. In one group of 42 patients with unexplained intrauterine growth retardation and subsequent short stature, we used single-strand conformation polymorphism analysis, followed by direct DNA sequencing of any abnormalities found. A second cohort consisted of 50 children with short stature who had elevated circulating IGF-I concentrations. Complete sequencing of the IGF-IR gene was performed with DNA from nine children. We also studied a control group of 43 children with normal birth weights. results In the first cohort, we identified one girl who was a compound heterozygote for point mutations in exon 2 of the IGF-IR gene that altered the amino acid sequence to Arg108Gln in one allele and Lys115Asn in the other. Fibroblasts cultured from the patient had decreased IGF-I-receptor function, as compared with that in control fibroblasts. No such mutations were found in the 43 controls. In the second group, we identified one boy with a nonsense mutation (Arg59stop) that reduced the number of IGF-I receptors on fibroblasts. Both children had intrauterine growth retardation and poor postnatal growth. conclusions Mutations in the IGF-IR gene that lead to abnormalities in the function or number of IGF-I receptors may also retard intrauterine and subsequent growth in humans.

2010

Hormone Research in Paediatrics, 2010

Background/Aims: GH insensitivity and IGF deficiency may result from aberrations of the GH receptor (GHR). We describe a 4-year-old child with modest growth failure and normal serum concentrations of GH-binding protein (GHBP), but clinical evidence of GH insensitivity. Method: Serum and DNA samples from the proband and his parents were analyzed. Results: The child had a height of –4 SD, elevated serum GH concentrations, abnormally low serum IGF-I and IGFBP-3 concentrations and normal GHBP concentrations. DNA analysis revealed compound heterozygosity for mutations of GHR, including a previously reported R211H mutation and a novel duplication of a nucleotide in exon 9 (899dupC), the latter resulting in a frameshift and a premature stop codon. Treatment with recombinant DNA-derived IGF-I resulted in growth acceleration. Conclusion: Mutations affecting the intracellular domain of the GHR can result in GH insensitivity and IGF deficiency, despite normal serum concentrations of GHBP. The ...

Journal of the Endocrine Society

Context: Autosomal-recessive mutations in the growth hormone receptor (GHR) are the most common causes for primary growth hormone insensitivity (GHI) syndrome with classical GHI phenotypically characterized by severe short stature and marked insulin-like growth factor (IGF)-I deficiency. We report three families with dominant-negative heterozygous mutations in the intracellular domain of the GHR causing a nonclassical GHI phenotype. Objective: To determine if the identified GHR heterozygous variants exert potential dominant-negative effects and are the cause for the GHI phenotype in our patients. Results: All three mutations (c.964dupG, c.920_921insTCTCAAAGATTACA, and c.945+2T>C) are predicted to result in frameshift and early protein termination. In vitro functional analysis of variants c.964dupG and c.920_921insTCTCAAAGATTACA (c.920_921ins14) suggests that these variants are expressed as truncated proteins and, when coexpressed with wild-type GHR, mimicking the heterozygous sta...

European Journal of Endocrinology, 2004

OBJECTIVE: GH insensitivity syndrome (GHIS; Laron syndrome) is clinically characterized by severe postnatal growth failure and very low serum levels of IGF-I despite increased secretion of GH. This mainly autosomal recessive syndrome is clinically indistinguishable from isolated GH deficiency (IGHD). Fifty-one different mutations in the GH receptor (GHR) gene have been discovered, whereas only three deletions causing the disorder have been reported so far. In this report, we describe a consanguineous family from Sri Lanka with a novel deletion of 4097 bp in length encompassing exon 5. SUBJECTS AND METHODS: Parents of normal phenotype presented their second child (boy) to our clinic at the age of 7 months with severe growth retardation and the clinical features of IGHD (58 cm, -6.1 standard deviation score (SDS); 5.7 kg, -3.4 SDS). Assessment, however, revealed GHIS with absent GH-binding protein. Thereafter, the patient received intermittent recombinant human IGF-I (rhIGF-I; 80 micr...

Growth Hormone & IGF Research, 2007

Objective: Genetic factors play an expanding role in understanding growth hormone (GH) disorders, therefore the German KIMS Pharmacogenetics Study was initiated with the aim of genotyping various GH-/IGF-I-axis-related genes of GH-deficient adult patients to investigate genotype:phenotype relationships and response to GH therapy. Patients and methods: 129 consecutively enrolled GH-deficient adult patients were genotyped for variant 1 (V1) of the alternatively spliced noncoding exons in the 5 0-untranslated region and for the nine coding exons of the GH receptor (GHR) gene, which obviously play a striking role in the function of the GH-IGF-I-axis. After detection of a heterozygous, non-synonymous mutation R179C in exon 6 in one single patient with acquired GH-deficiency (GHD) in late adulthood, analysis of her clinical data followed, leading to the diagnosis of mild short stature (À1.5 SD). For further endocrine evaluation, five pituitary stimulation tests (arginine) of this patient were statistically compared to stimulation tests (arginine) of ten GH-deficient control patients, retrospectively. Results: The formerly in patients with Laron syndrome and idiopathic short stature reported mutation R179C leads to an amino acid change from an arginine residue (codon CGC) to a cysteine residue (codon TGC) in position 179 of the extracellular domain of the GHR. Statistical analysis revealed significant decreased IGF-I/GH 0 ratio (p = 0.004) and IGF-I/GH max ratio (p = 0.

European journal of endocrinology, 1998

The causes of growth retardation of children with thalassaemia major are multifactorial. We studied the GH response to provocation by clonidine and glucagon, measured the circulating concentrations of insulin, IGF-I, IGF-binding protein-3 (IGFBP-3) and ferritin, and evaluated IGF-I generation after a single dose of GH (0.1 mg/kg per dose) in 15 prepubertal patients with thalassaemia, 15 age-matched children with constitutional short stature (CSS) (height standard deviation score less than ¹2, with normal GH response to provocation) and 11 children with isolated GH deficiency (GHD). Children with thalassaemia had significantly lower peak GH response to provocation by clonidine and glucagon (6:2 Ϯ 2:3 and 6:8 Ϯ 2:1 mg/l respectively) than the CSS group (18:6 Ϯ 2:7 and 16:7 Ϯ 3:7 mg/l respectively). They had significantly decreased circulating concentrations of IGF-I and IGFBP-3 (47:5 Ϯ 19 ng/ml and 1:2 Ϯ 0:27 mg/l respectively) compared with those with CSS (153 Ϯ 42 ng/ ml and 2:06 Ϯ 0:37 mg/l respectively), but the IGF-I and IGFBP-3 concentrations were not different from those with GHD (56 Ϯ 25 ng/ml and 1:1 Ϯ 0:32 mg/l respectively). These data demonstrate that the GH-IGF-I-IGFBP-3 axis in thalassaemic children is defective. Serum ferritin concentration correlated significantly with GH peak response to provocation (r ¼ ¹0:36, P < 0:05) and circulating IGF-I (r ¼ ¹0:47, P < 0:01) and IGFBP-3 (r ¼ ¹0:42, P < 0:01) concentrations. In the IGF-I generation test, after GH injection, the thalassaemic children had significantly lower IGF-I and IGFBP-3 levels 86:7 Ϯ 11:2 ng/ml and 2:05 Ϯ 0:51 mg/l respectively) than those in the CSS group (226 Ϯ 45:4 ng/ ml and 2:8 Ϯ 0:43 mg/l respectively). The IGF-I response was significantly higher in children with GHD (158 Ϯ 50 ng/ml) than in thalassaemic children. Six short (height standard deviation score less than ¹2) thalassaemic children who had defective GH response to provocation (<10 mg/l), all the children with GHD and eight short normal children (CSS) were treated for 1 year with human GH (18 units/m 2 per week divided into daily s.c. doses). After 1 year of GH therapy there was a marked acceleration of growth velocity in both thalassaemic children (from 3:8 Ϯ 0:6 cm/year to 7:2 Ϯ 0:8 cm/year) and controls. However, the linear acceleration of growth velocity on GH therapy was significantly slower in thalassaemic children (3:3 Ϯ 0:3 cm/year increment) compared with those with CSS (5:3 Ϯ 0:4 cm/year increment) and GHD (6:9 Ϯ 1:2 cm/year increment) (P < 0:05). Their circulating IGF-I concentration (105 Ϯ 36 ng/ml) was significantly lower than those for CSS (246 Ϯ 58 ng/ml) and GHD (189 Ϯ 52 ng/ml) after 1 year of GH therapy. These data prove that some children with b-thalassaemia major have a defective GH-IGF-I-IGFBP-3 axis and suggest the presence of partial resistance to GH.

Journal of Medical Genetics, 2003

The Journal of Clinical Endocrinology and Metabolism, 1999

Measurement of the insulin-like growth factors (IGFs) and their binding proteins has become commonplace in the indirect assessment of the integrity of the GH axis. However, the relative effect of GH deficiency (GHD) on each component of the IGF axis and the merit of any one parameter as a diagnostic test have not been defined in a homogeneous population across all ages. We therefore measured IGF-I, IGF-II, IGF-binding protein-1 (IGFBP-1), IGFBP-2, IGFBP-3, and acid labile subunit (ALS) in 27 GHD subjects (aged 5-82 yr) from an extended kindred in Northeast Brazil with an identical GHRH receptor mutation and in 55 indigenous controls (aged 5-80 yr). The effect of GHD on the theoretical distribution of IGFs between the IGFBPs and the ternary complex was also examined. All components of the IGF axis, measured and theoretical, showed complete separation between GHD and control subjects, except IGFBP-1 and IGFBP-2 concentrations, which did not differ. The most profound effects of GHD were on total IGF-I, IGF-I in the ternary complex, and ALS. The proportion of IGF-I associated with IGFBP-3 remained constant throughout life, but was significantly lower in