Mutation analysis of the muscarinic cholinergic receptor genes in isolated growth hormone deficiency type IB.
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ABSTRACT: Background
Isolated GH deficiency (IGHD) is familial in 5-30% of patients. The most frequent form (IGHD-IB) has autosomal recessive inheritance, and it is known that it can be caused by mutations in the GHRH receptor (GHRHR) gene or in the GH gene. However, most forms of IGHD-IB have an unknown genetic cause. In normal subjects, muscarinic cholinergic stimulation causes an increase in pituitary GH release, whereas its blockade has the opposite effect, suggesting that a muscarinic acetylcholine receptor (mAchR) is involved in stimulating GH secretion. Five types of mAchR (M(1)-M(5)) exist. A transgenic mouse in which the function of the M(3) receptor was selectively ablated in the central nervous system has isolated GH deficiency similar to animals with defective GHRH or GHRHR gene.Objective
We hypothesized that mAchR mutations may cause a subset of familial IGHD.Patients/methods
After confirming the expression of M(1)-M(5) receptor mRNA in human hypothalamus, we analyzed the index cases of 39 families with IGHD-IB for mutations in the genes encoding for the five receptors. Coding sequences for each of the five mAchRs were subjected to direct sequencing.Results
In one family, an affected member was homozygous for a M(3) change in codon 65 that replaces valine with isoleucine (V65I). The V65I receptor was expressed in CHO cells where it had normal ability to transmit methacholine signaling.Conclusion
mAchR mutations are absent or rare (less than 2.6%) in familial IGHD type IB.
SUBMITTER: Mohamadi A
PROVIDER: S-EPMC2708943 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundIsolated growth hormone deficiency (IGHD) is caused by a severe shortage or absence of growth hormone (GH), which results in aberrant growth and development. Patients with IGHD type IV (IGHD4) have a short stature, reduced serum GH levels, and delayed bone age.ObjectivesTo identify the causative mutation of IGHD in a consanguineous family comprising four affected patients with IGHD4 (MIM#618157) and explore its functional impact in silico.MethodsClinical and radiological studies were performed to determine the phenotypic spectrum and hormonal profile of the disease, while whole-exome sequencing (WES) and Sanger sequencing were performed to identify the disease-causing mutation. In-silico studies involved protein structural modeling and docking, and molecular dynamic simulation analyses using computational tools. Finally, data from the Qatar Genome Program (QGP) were screened for the presence of the founder variant in the Qatari population.ResultsAll affected individuals presented with a short stature without gross skeletal anomalies and significantly reduced serum GH levels. Genetic mapping revealed a homozygous nonsense mutation [NM_000823:c.G214T:p.(Glu72*)] in the third exon of the growth-hormone-releasing hormone receptor gene GHRHR (MIM#139191) that was segregated in all patients. The substituted amber codon (UAG) seems to truncate the protein by deleting the C-terminus GPCR domain, thus markedly disturbing the GHRHR receptor and its interaction with the growth hormone-releasing hormone.ConclusionThese data support that a p.Glu72* founder mutation in GHRHR perturbs growth hormone signaling and causes IGHD type IV. In-silico and biochemical analyses support the pathogenic effect of this nonsense mutation, while our comprehensive phenotype and hormonal profiling has established the genotype-phenotype correlation. Based on the current study, early detection of GHRHR may help in better therapeutic intervention.
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Project description:When a child is not following the normal, predicted growth curve, an evaluation for underlying illnesses and central nervous system abnormalities is required, and appropriate consideration should be given to genetic defects causing growth hormone (GH) deficiency (GHD). Because Insulin-like Growth Factor-I (IGF-I) plays a pivotal role, GHD could also be considered as a form of IGF-I deficiency (IGFD). Although IGFD can develop at any level of the GH-releasing hormone (GHRH)-GH-IGF axis, a differentiation should be made between GHD (absent to low GH in circulation) and IGFD (normal to high GH in circulation). The main focus of this review is on the GH gene, the various gene alterations and their possible impact on the pituitary gland. However, although transcription factors regulating the pituitary gland development may cause multiple pituitary hormone deficiency, they may present initially as GHD.
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Project description:Introduction and importanceGrowth hormone (GH) deficiency is the most common hypopituitarism disorder. We highlight the challenges to its diagnosis and management in the setting of a developing country.Case descriptionA 14-year-old came with a chief complaint of inability to menstruate. Menarche was at 12-years old, lasted 7 days, soaking 2 pads/day which discontinued shortly after. Thelarche was at 12-years-old and her breast is at Tanner stage 3. Her axillary and pubic hair are at Tanner stage 1. Height was 120 cm, weight 34.8 kg, height for age z-score < -3. Her lab results were normal for estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin. Bone age was suitable for age. Magnetic resonance imaging revealed pituitary gland hypoplasia (5.3 mm). A hormonal panel 3 years prior showed abnormally low GH level but normal cortisol and thyroid hormone levels. She was diagnosed with isolated growth hormone deficiency (IGHD) with delayed puberty. She was treated with medroxyprogesterone tablets once daily, after which her menstruation restarted. However, due to her economic background, she declined genetic tests, discontinued her medication and amenorrhea recurred.Clinical discussionAmenorrhea present after a brief menarche should alert gynaecologists of a possible multi-hormone disorder with an underlying structural abnormality. IGHD may be due to a structural abnormality, such as pituitary gland hypoplasia. Unfortunately, economic reasons prevented the patient from receiving optimal treatment.ConclusionIGHD rarely presents with a gynaecological complaint. Hormonal and genetic tests along with imaging should be undertaken. Growth hormone supplementation is the treatment of choice.
| S-EPMC9793238 | biostudies-literature
Project description:IntroductionGrowth hormone (GH) secretion and release is a complex and highly regulated process. Any alteration disturbing synthesis, secretion or biological action of GH, results into growth hormone deficiency (GHD). GHD is of two types-isolated growth hormone deficiency (IGHD) and combined pituitary hormone deficiency (CPHD), of which IGHDis more common. The genes implicated in its etiology are growth hormone 1(GH1) and receptor of growth hormone-releasing hormone (GHRHR). Mutations within the coding region and/or either entire or partial deletions of the GH1gene lead to IGHD. In addition, GH1 possesses upstream regulatory elements and a promoter with binding sites for various transcription factors, which control its expression.AimThe study was planned with an aim to identify entire GH1 locus deletion, mutations in the GH1 coding region and sequence variations (polymorphisms) in the promoter region of the gene in patients with IGHD.Materials and methodsThirty patients clinically diagnosed with IGHD and 30 healthy individuals who formed the controls were enrolled for the study. Genomic DNA was isolated from peripheral blood sample and processed for amplification of the desired regions followed by direct sequencing and/or restriction endonuclease digestion.ResultsOut of the 30 IGHD patients screened, 20% of the cases showed consanguinity and 16% had a positive family history. Seven percentage of the patients showed homozygous deletion of the GH1gene while rest of them had heterozygous deletion. Screening of the coding region of GH1 showed sequence variations in exon 1 in 20% of the patients whereas the promoter region showed the presence of polymorphisms-rs2005171 in 20%, rs2005172 in 15% and rs11568828 in 18% of the cases. The haplotype comprising rs2005171 and rs2005172 was observed in four patients.ConclusionThe present study is an attempt to characterize the GH1 locus in IGHD patients. To the best of our knowledge this is the first study of its kind where entire GH1locus, upstream regulatory elements and promoter region have been studied. Such an analysis would provide valuable information on the etiology of IGHD.
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Project description:BackgroundThe study aimed to compare the growth responses to 3 years of growth hormone (GH) treatment in children and adolescents with GH deficiency (GHD) according to idiopathic, organic, isolated (IGHD), and multiple pituitary hormone deficiency (MPHD).MethodsTotal 163 patients aged 2-18 years (100 males and 63 females; 131 idiopathic and 32 organic GHD; 129 IGHD and 34 MPHD) were included from data obtained from the LG Growth Study. Parameters of growth responses and biochemical results were compared during the 3-year GH treatment.ResultsThe baseline age, bone age (BA), height (Ht) standard deviation score (SDS), weight SDS, mid-parental Ht SDS, predicted adult Ht (PAH) SDS, and insulin like growth factor-1 (IGF-1) SDS were significantly higher in the organic GHD patients than in the idiopathic GHD patients, but peak GH on the GH-stimulation test, baseline GH dose, and mean 3-year-GH dosage were higher in the idiopathic GHD patients than in the organic GHD patients. The prevalence of MPHD was higher in the organic GHD patients than in the idiopathic GHD patients. Idiopathic MPHD subgroup showed the largest increase for the ΔHt SDS and ΔPAH SDS during GH treatment, and organic MPHD subgroup had the smallest mean increase after GH treatment, depending on ΔIGF-1 SDS and ΔIGF binding protein-3 (IGFBP-3) SDS. The growth velocity and the parental-adjusted Ht gain were greater in the idiopathic GHD patients than the organic GHD patients during the 3-year GH treatment, which may have been related to the different GH dose, ΔIGF-1 SDS, and ΔIGFBP-3 SDS between two groups. Multiple linear regression analysis revealed that baseline IGF-1 SDS, BA, and MPH SDS in idiopathic group and baseline HT SDS in organic group are the most predictable parameters for favorable 3-year-GH treatment.ConclusionThe 3-year-GH treatment was effective in both idiopathic and organic GHD patients regardless of the presence of MPHD or underlying causes, but their growth outcomes were not constant with each other. Close monitoring along with appropriate dosage of GH and annual growth responses, not specific at baseline, are more important in children and adolescents with GHD for long-term treatment.Trial registrationClinicalTrials.gov Identifier: NCT01604395.
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Project description:BackgroundA case of isolated growth hormone deficiency type IA (IGHD IA) caused by novel compound heterozygous mutation in the GH1 gene was reported in this study, which aimed to provide insights that will benefit future diagnosis and treatment.Case presentationWe analyzed and summarized the clinical data and genetic test results from a patient with IGHD admitted in March 2019 to the Department of Pediatrics Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. We described the results from a 1-year-9-months old female, whose chief complaint was "growth retardation for more than one year". Her birth length was 49.0 cm, and her birth weight was 3.05 kg. Suboptimal intake (breastfeeding) jaundice lasted for approximately two months following birth. When evaluated at the age of 1-year-9-months old, the patient's height was 61.0 cm (- 7.24 SD), and her weight was 6.4 kg (- 1.50 SD). The patient's physical characteristics included yellowish hair, large and unclosed anterior fontanelles, raised forehead, and a low and flat nose. The major abnormalities observed from the auxiliary examinations included low GH (< 0.05 μg/l), low IGF-1 (16.99 μg/l), and elevated TSH (6.97 mIU/l). Genetic testing revealed two heterozygous variants: a splicing mutation (NG_011676.1(NM_022560.4): c.10 + 1G>T, inherited from her mother) in intron 1 of the GH1 gene and a deletion that encompassed the same gene (chr17: 61973811-61996255, inherited from her father). After hormone replacement therapy with L-thyroxine and recombinant human GH (rhGH), the patient's thyroid function returned to normal, and her serum IGF-1 level significantly improved, which resulted in an accelerated increase in height.ConclusionThis study described a case of IGHD caused by novel compound heterozygous mutations in the GH1 gene. This study suggested that closer attention should be directed to genetic testing and diagnosis based on clinical characteristics to avoid misdiagnosis.
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Project description:ContextDominant-negative GH1 mutations cause familial isolated growth hormone deficiency type II (IGHD II), which is characterized by GH deficiency, occasional multiple anterior pituitary hormone deficiencies, and anterior pituitary hypoplasia. The basis of the variable expression and progression of IGHD II among relatives who share the same GH1 mutation is poorly understood.ObjectiveWe hypothesized that the cellular ratios of mutant/normal GH1 transcripts would correlate with the severity of the IGHD II phenotype. We determined the relative amounts of mutant and normal GH1 transcripts in cell lines and correlated transcript ratios with severity.Design and patientsMembers of the same IGHD II kindred were genotyped for the GH1 E3+1 G/A mutation by DNA sequencing. Ratios of their 17.5-kDa (mutant)/22-kDa (normal) GH1 transcripts were determined in cultured lymphocytes (CLs), and these ratios were correlated with height sd scores obtained before GH replacement therapy.ResultsRatios of 17.5-/22-kDa GH1 transcripts in CLs from family members with the same IGHD II mutation correlated with differences in their height SD scores.ConclusionsOur findings suggest that expression levels of both the mutant and normal GH1 allele are important in the pathogenesis of IGHD II, that the ratio of mutant/normal transcripts may be a predictive marker of the penetrance and severity of IGHD II, and that CLs may be useful as surrogates to study GH1 transcript expression of subjects whose anterior pituitary cells are not available.
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Project description:IntroductionThe growth hormone deficiency (GHD) diagnosis is controversial especially due to low specificity of growth hormone (GH) stimulation tests. It is therefore believed that children diagnosed with GHD form a heterogeneous group with growth disorder frequently independent on GH function. No study evaluating the complex etiology of growth failure in children with diagnosed GHD has been performed thus far.AimsTo discover genetic etiology of short stature in children with diagnosed GHD from families with short stature.MethodsFifty-two children diagnosed with primary GHD and vertically transmitted short stature (height SDS in the child and his/her shorter parent <-2 SD) were included to our study. The GHD diagnosis was based on growth data suggestive of GHD, absence of substantial disproportionality (sitting height to total height ratio <-2 SD or >+2 SD), IGF-1 levels <0 for age and sex specific SD and peak GH concentration <10 ug/L in two stimulation tests. All children were examined using next-generation sequencing methods, and the genetic variants were subsequently evaluated by American College of Medical Genetics standards and guidelines.ResultsThe age of children at enrollment into the study was 11 years (median, IQR 9-14 years), their height prior to GH treatment was -3.0 SD (-3.6 to -2.8 SD), IGF-1 concentration -1.4 SD (-2.0 to -1.1 SD), and maximal stimulated GH 6.3 ug/L (4.8-7.6 ug/L). No child had multiple pituitary hormone deficiency or a midbrain region pathology. Causative variant in a gene that affects growth was discovered in 15/52 (29%) children. Of them, only 2 (13%) had a genetic variant affecting GH secretion or function (GHSR and OTX2). Interestingly, in 10 (67%) children we discovered a primary growth plate disorder (ACAN, COL1A2, COL11A1, COL2A1, EXT2, FGFR3, NF1, NPR2, PTPN11 [2x]), in one (7%) a genetic variant impairing IGF-1 action (IGFALS) and in two (12%) a variant in miscellaneous genes (SALL4, MBTPS2).ConclusionsIn children with vertically transmitted short stature, genetic results frequently did not correspond with the clinical diagnosis of GH deficiency. These results underline the doubtful reliability of methods standardly used to diagnose GH deficiency.
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Project description:Congenital growth hormone deficiency (GHD) is a rare disease caused by disorders affecting the morphogenesis and function of the pituitary gland. It is sometimes found in isolation but is more frequently associated with multiple pituitary hormone deficiency. In some cases, GHD may have a genetic basis. The many clinical signs and symptoms include hypoglycaemia, neonatal cholestasis and micropenis. Diagnosis should be made by laboratory analyses of the growth hormone and other pituitary hormones, rather than by cranial imaging with magnetic resonance imaging. When diagnosis is confirmed, hormone replacement should be initiated. Early GH replacement therapy leads to more positive outcomes, including reduced hypoglycaemia, growth recovery, metabolic asset, and neurodevelopmental improvements.
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Project description:Splicing mutations in the human GH (hGH) gene (GH-1) that cause skipping of exon 3 result in a form of GH deficiency termed isolated GH deficiency type II (IGHD II). The GH-1 gene contains five exons; constitutive splicing produces the wild-type 22-kDa hormone, whereas skipping of exon 3 results in transcripts encoding a 17.5-kDa isoform that acts as a dominant-negative to block secretion of the wild-type hormone. Common characteristics of IGHD II include short stature due to impaired bone elongation, growth, and, in severe cases, anterior pituitary hypoplasia. Typically, IGHD II is treated by sc delivery of hGH, which can rescue stature but, unfortunately, does not inhibit pituitary hypoplasia. Direct destruction of transcripts encoding the dominant-negative 17.5-kDa isoform should both rescue stature and prevent hypoplasia. Here, we have used delivery of short hairpin RNAs to rescue a murine model of IGHD II by specifically targeting transcripts encoding the 17.5-kDa isoform using RNA interference. To our knowledge, this is the first example where a short hairpin RNA has been expressed to specifically degrade an incorrectly spliced transcript and rescue a dominant-negative disease phenotype in vivo.
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