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The Journal of Clinical Endocrinology... Jul 2021Severe forms of Growth Hormone Insensitivity (GHI) are characterized by extreme short stature, dysmorphism and metabolic anomalies.
CONTEXT
Severe forms of Growth Hormone Insensitivity (GHI) are characterized by extreme short stature, dysmorphism and metabolic anomalies.
OBJECTIVE
Identification of the genetic cause of growth failure in 3 'classical' GHI subjects.
DESIGN
A novel intronic GHR variant was identified, and in vitro splicing assays confirmed aberrant splicing. A 6Ω pseudoexon GHR vector and patient fibroblast analysis assessed the consequences of the novel pseudoexon inclusion and the impact on GHR function.
RESULTS
We identified a novel homozygous intronic GHR variant (g.5:42700940T>G, c.618 + 836T> G), 44bp downstream of the previously recognized intronic 6Ψ GHR pseudoexon mutation in the index patient. Two siblings also harbored the novel intronic 6Ω pseudoexon GHR variant in compound heterozygosity with the known GHR c.181C>T (R43X) mutation. In vitro splicing analysis confirmed inclusion of a 151bp mutant 6Ω pseudoexon not identified in wild-type constructs. Inclusion of the 6Ω pseudoexon causes a frameshift resulting in a non-functional truncated GHR lacking the transmembrane and intracellular domains. The truncated 6Ω pseudoexon protein demonstrated extracellular accumulation and diminished activation of STAT5B signaling following growth hormone stimulation.
CONCLUSION
Novel GHR 6Ω pseudoexon inclusion results in loss of GHR function consistent with a severe GHI phenotype. This represents a novel mechanism of Laron syndrome and is the first deep intronic variant identified causing severe postnatal growth failure. The 2 kindreds originate from the same town in Campania, Southern Italy, implying common ancestry. Our findings highlight the importance of studying variation in deep intronic regions as a cause of monogenic disorders.
PubMed: 34318893
DOI: 10.1210/clinem/dgab550 -
Growth Hormone & IGF Research :... 2020Individuals affected with two genetic syndromes identified in Ecuador have severe short stature and diminished insulin secretion, along with essentially different GH...
UNLABELLED
Individuals affected with two genetic syndromes identified in Ecuador have severe short stature and diminished insulin secretion, along with essentially different GH counterregulatory effects on insulin action, which leads to the appearance of opposing metabolic phenotypes. In the case of Laron syndrome, subjects have enhanced insulin sensitivity and diminished incidence of type 2 diabetes mellitus. In the other clinical entity, individuals have innate insulin resistance, a varying degree of carbohydrate metabolism disturbances, glucose intolerance, and eventually insulin-resistant diabetes mellitus. Since both groups have diminished insulin secretion, the standard homeostatic minimal models for assessment of insulin sensitivity and resistance were used to see if they could properly identify the metabolic status, especially considering that these methodologies are simple and non-invasive procedures.
METHODS
Fasting insulin concentrations, fasting glucose/fasting insulin ratio and various minimal models were determined in individuals from the two syndromic cohorts, as well as in a control group made of first-degree normal relatives of the insulin-resistant phenotype subjects.
RESULTS
The metabolic characteristics of enhanced insulin sensitivity in one of the syndromes and innate insulin resistance in the other could not be properly ascertained by the selected methodology. Furthermore, results were confusing and even discrepant with the clinical findings.
CONCLUSIONS
The standard homeostatic minimal models could not properly identify or discriminate insulin sensitivity and resistance in subjects with inherently diminished secretion. It is thereby suggested that these models should be used with caution in clinical situations where reduced secretion of the metabolic peptide is found or suspected.
Topics: Case-Control Studies; Dwarfism; Glucose Intolerance; Growth Disorders; Human Growth Hormone; Humans; Insulin Resistance; Laron Syndrome; Prognosis; Syndrome
PubMed: 32763832
DOI: 10.1016/j.ghir.2020.101339 -
Growth Hormone & IGF Research :... Jun 2020Laron Syndrome (LS), (OMIM# 262500), a rare recessively inherited disease caused by deletions or mutations of the GH receptor, gene characterized by dwarfism with low or...
Laron Syndrome (LS), (OMIM# 262500), a rare recessively inherited disease caused by deletions or mutations of the GH receptor, gene characterized by dwarfism with low or undetectable serum IGF-I in the presence of high serum GH. In addition to dwarfism, the IGF-I deficiency leads to metabolic abnormalities including aberrations in protein biosynthesis and homeostasis. The only available treatment for LS patients is (r)IGF-I administration. The present study was aimed to determine the plasma concentrations of specific amino acids and their metabolites in the blood of untreated and IGF-I-treated LS patients. The study involved a total of 10 LS patients (3 untreated and 7 treated), 2 heterozygote mothers and 3aged subjects. Forty healthy boys and girls served as controls. The analysis of amino acids and their metabolites was performed using the LC-MS/MS analysis and Waters Acc-Q Tag ultra-derivatization kit. Serum IGF-I levels were measured by a one-step sandwich chemiluminescence immunoassay. The results revealed that long-term IGF-I deficiency in LS patients led to abnormal changes in the plasma amino acids metabolism, such as low levels of plasma citrulline, sarcosine and taurine that increased upon IGF-I replacement. The plasma amino acid levels of the heterozygous family members resembled those of the untreated LS patients, whereas the pattern in the 2 double heterozygote sisters previously treated with IGF-I resembled that of the presently IGF-I-treated patients. In addition, plasma ɑ-amino adipic acid levels were elevated in both untreated and IGF-I-treated patients. In summary our data revealed that LS patients, a condition associated with congenital IGF-I deficiency, have an abnormal plasma amino acid metabolism that is partially restored by IGF-I treatment.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Amino Acids; Biomarkers; Case-Control Studies; Child; Child, Preschool; Female; Follow-Up Studies; Growth Disorders; Hearing Loss, Sensorineural; Humans; Infant; Insulin-Like Growth Factor I; Laron Syndrome; Male; Middle Aged; Pilot Projects; Prognosis; Young Adult
PubMed: 32200226
DOI: 10.1016/j.ghir.2020.02.001 -
Cellular and Molecular Life Sciences :... Mar 2023Signal transducer and activator of transcription (STAT) proteins act downstream of cytokine receptors to facilitate changes in gene expression that impact a range of...
Signal transducer and activator of transcription (STAT) proteins act downstream of cytokine receptors to facilitate changes in gene expression that impact a range of developmental and homeostatic processes. Patients harbouring loss-of-function (LOF) STAT5B mutations exhibit postnatal growth failure due to lack of responsiveness to growth hormone as well as immune perturbation, a disorder called growth hormone insensitivity syndrome with immune dysregulation 1 (GHISID1). This study aimed to generate a zebrafish model of this disease by targeting the stat5.1 gene using CRISPR/Cas9 and characterising the effects on growth and immunity. The zebrafish Stat5.1 mutants were smaller, but exhibited increased adiposity, with concomitant dysregulation of growth and lipid metabolism genes. The mutants also displayed impaired lymphopoiesis with reduced T cells throughout the lifespan, along with broader disruption of the lymphoid compartment in adulthood, including evidence of T cell activation. Collectively, these findings confirm that zebrafish Stat5.1 mutants mimic the clinical impacts of human STAT5B LOF mutations, establishing them as a model of GHISID1.
Topics: Animals; Humans; Zebrafish; STAT5 Transcription Factor; Laron Syndrome; Mutation; Growth Hormone
PubMed: 36995466
DOI: 10.1007/s00018-023-04759-y -
Growth Hormone & IGF Research :... Apr 2020We have shown that subjects with Laron syndrome (LS) due to growth hormone receptor deficiency (GHRD) and their relatives have comparable brain structure and function;...
BACKGROUND
We have shown that subjects with Laron syndrome (LS) due to growth hormone receptor deficiency (GHRD) and their relatives have comparable brain structure and function; moreover, the brain of individuals affected with GHRD appears like those of younger people. While the functionally absent growth hormone receptor and the diminished concentrations of the insulin-like growth factor-I have been associated to these findings, the role of the insulin-glucose axis is emerging as an unavoidable consideration when determining the aetiology of these observations. In consequence, we decided to search for the potential and discrete associations between the neurological findings and several parameters of carbohydrate metabolism that might exist in the subjects affected with GHRD.
SUBJECTS AND METHODS
Individuals affected with GHRD were compared to relative controls. Besides standard measures of anthropometry, body composition and brain characteristics, the elements of the carbohydrate metabolism (CHO), including glucose, insulin, triacylglycerol and the free insulin growth factor binding protein 1 (IGFBP1) concentrations were determined. In addition, the correlations existing between the parameters of CHO and brain characteristics were established.
RESULTS
Besides the phenotypical characteristics of GHRD subjects, including those of brain structure and function, enhanced insulin sensitivity, and other minor, we observed that the insulin-regulated IGFBP1 had a consistent negative correlation with the main elements of the carbohydrate metabolism only in the individuals affected with the disease, and not in their relatives.
CONCLUSIONS
When compared to their relatives, subjects with GHRD who lack the counter-regulatory effects of GH on the insulin axis, despite their increased risk factor profile due to obesity and increased body fat percentage, have a healthy and younger looking brain associated to an enhanced and coordinated insulin sensitivity. Furthermore, it was observed that in the GHRD subjects IGFBP1 negatively correlates, in a constant and systematic manner, with the main elements of the CHO metabolism. These observations suggest a direct relationship between an efficient insulin sensitivity and a healthy brain.
Topics: Adipose Tissue; Adult; Blood Glucose; Body Composition; Brain; Carbohydrate Metabolism; Case-Control Studies; Family; Fasting; Female; Functional Neuroimaging; Humans; Insulin; Insulin Resistance; Insulin-Like Growth Factor Binding Protein 1; Laron Syndrome; Magnetic Resonance Imaging; Male; Middle Aged; Obesity; Postprandial Period; Receptors, Somatotropin; Triglycerides
PubMed: 32145513
DOI: 10.1016/j.ghir.2020.02.004 -
Growth Hormone & IGF Research :... Apr 2020The efficacy and safety of IGF-1 therapy in patients with severe primary IGF-I deficiency has been evaluated for more than two decades. Most of the therapeutic...
The efficacy and safety of IGF-1 therapy in patients with severe primary IGF-I deficiency has been evaluated for more than two decades. Most of the therapeutic experience comes from treating the more severe IGF-I deficient patients, who usually present with a phenotype characteristic of growth hormone receptor deficiency or Laron syndrome. Although most of these patients do not experience enough catchup growth to bring their height into normal range, many individuals achieve an adult height significantly greater than what would have been predicted in the absence of IGF-1 therapy. In the last couple of years a few reports on the benefit of IGF-1 therapy for patients with milder types of IGF-I deficiency have also been published, with variable height outcomes. More short children with prior diagnosis of idiopathic short stature are now being diagnosed with specific molecular defects of the growth hormone/IGF-I axis. Because of this, the clinical spectrum of primary IGF-I deficiency is widening to include many patients with such a milder phenotype, creating a need for well-designed long-term clinical studies evaluating the growth response to growth promoting agents such as rhIGF-1 in these individuals.
Topics: Child; Child, Preschool; Human Growth Hormone; Humans; Insulin-Like Growth Factor Binding Protein 3; Insulin-Like Growth Factor I; Laron Syndrome; Pituitary Function Tests; Receptors, Somatotropin; Recombinant Proteins; Severity of Illness Index
PubMed: 31982729
DOI: 10.1016/j.ghir.2020.01.001 -
International Journal of Molecular... Feb 2021Anti-Müllerian hormone (AMH) is secreted by Sertoli or granulosa cells. Recent evidence suggests that AMH may play a role in the pathogenesis of hypogonadotropic...
Anti-Müllerian hormone (AMH) is secreted by Sertoli or granulosa cells. Recent evidence suggests that AMH may play a role in the pathogenesis of hypogonadotropic hypogonadism (HH) and that its serum levels could help to discriminate HH from delayed puberty. Moreover, the growth hormone (GH)/insulin-like growth factor 1 (IGF1) system may be involved in the function of gonadotropin-releasing hormone (GnRH) neurons, as delayed puberty is commonly found in patients with GH deficiency (GHD) or with Laron syndrome, a genetic form of GH resistance. The comprehension of the stimuli enhancing the migration and secretory activity of GnRH neurons might shed light on the causes of delay of puberty or HH. With these premises, we aimed to better clarify the role of the AMH, GH, and IGF1 on GnRH neuron migration and GnRH secretion, by taking advantage of previously established models of immature (GN11 cell line) and mature (GT1-7 cell line) GnRH neurons. Expression of Amhr, Ghr, and Igf1r genes was confirmed in both cell lines. Cells were then incubated with increasing concentrations of AMH (1.5-150 ng/mL), GH (3-1000 ng/mL), or IGF1 (1.5-150 ng/mL). All hormones were able to support GN11 cell chemomigration. AMH, GH, and IGF1 significantly stimulated GnRH secretion by GT1-7 cells after a 90-min incubation. To the best of our knowledge, this is the first study investigating the direct effects of GH and IGF1 in GnRH neuron migration and of GH in the GnRH secreting pattern. Taken together with previous basic and clinical studies, these findings may provide explanatory mechanisms for data, suggesting that AMH and the GH-IGF1 system play a role in HH or the onset of puberty.
Topics: Animals; Anti-Mullerian Hormone; Cell Movement; Cells, Cultured; Gonadotropin-Releasing Hormone; Human Growth Hormone; Insulin-Like Growth Factor I; Mice; Neurons
PubMed: 33671044
DOI: 10.3390/ijms22052445 -
Malaysian Orthopaedic Journal Mar 2020Marjolin's ulcer is an atypical malignancy that develops from deep scars of chronically traumatised skin. Laron syndrome (LS) is a rare autosomal recessive growth...
Marjolin's ulcer is an atypical malignancy that develops from deep scars of chronically traumatised skin. Laron syndrome (LS) is a rare autosomal recessive growth retardation from a mutation in the growth hormone receptor (GHR) gene leading to defective GHR, growth hormone insensitivity and eventual low levels of insulin-like growth factor type 1 (IGF-1). Affected individuals present with proportionate dwarfism and other characteristic physical defects, but at the same time are conferred protection against cancer due to low serum levels of IGF-1. We report an exceptional case of Marjolin's ulcer in the foot of a female LS patient 30 years after she sustained flame burns as a 6-month-old baby. Three months before coming to us, she had a 2x3cm ulcer that turned into a rapidly enlarging fungating mass involving the leg, ankle, and foot. Histopathologic analysis of an incision biopsy showed well-differentiated squamous cell carcinoma. The extent of her lesion precluded wide excision. Below knee amputation was done. A second biopsy confirmed the histopathologic diagnosis. This is the first reported case in the literature of Marjolin's ulcer in LS which raises the possibility that IGF-1 deficiency does not completely protect against squamous cell cancer.
PubMed: 32296486
DOI: 10.5704/MOJ.2003.012 -
Clinical Endocrinology Apr 2020To report a novel mutation in GHR and to characterize a novel mechanism of nonclassical growth hormone insensitivity.
OBJECTIVE
To report a novel mutation in GHR and to characterize a novel mechanism of nonclassical growth hormone insensitivity.
CONTEXT
Laron syndrome (LS) is a well-described disorder of growth hormone insensitivity due to mutations in the growth hormone receptor (GHR) that leads to short stature. Biochemically, LS patients classically have elevated levels of growth hormone (GH), but low levels of insulin-like growth factor (IGF)-1, IGF binding protein (IGFBP)-3 and GH binding protein (GHBP).
DESIGN
Case presentation with in vitro functional studies.
PATIENTS
A young male Caucasian child with short stature was found to have growth hormone insensitivity manifested by elevated levels of GH and GHBP.
MEASUREMENTS
Growth hormone stimulation tests revealed baseline GH level of 20.9 µg/L and maximum stimulated GH level of 52.7 µg/L and GHBP level of 4868 pmol/L. GHR gene sequencing revealed a novel heterozygous nonsense mutation (c.800G > A, p.Trp267*) in the transmembrane domain of the receptor. Immunoblot analysis of transfected GHR p.Trp267* in HEK293 revealed inhibition of GH-induced STAT5 signalling that was overcome with increasing doses of recombinant human GH.
RESULTS
Using an in vitro model, we show that elevated levels of GHBP inhibit the action of GH. Furthermore, our studies demonstrate that this inhibition by GHBP can be overcome by increasing doses of recombinant human GH.
CONCLUSIONS
To our knowledge, this is the first study to demonstrate in vitro that elevated levels of GHBP attenuate the effect of GH and inhibit GH-induced signalling, thereby leading to short stature. Though this inhibition was overcome in vitro with supraphysiologic doses of GH, significantly above endogenously available GH, it remains to be seen whether such an effect can be replicated in vivo.
Topics: Carrier Proteins; Child; Codon, Nonsense; Growth Hormone; HEK293 Cells; Human Growth Hormone; Humans; Insulin-Like Growth Factor I; Male; Receptors, Somatotropin
PubMed: 31883394
DOI: 10.1111/cen.14148 -
The Journal of Biological Chemistry Jan 2022SEC23B is one of two vertebrate paralogs of SEC23, a key component of the coat protein complex II vesicles. Complete deficiency of SEC23B in mice leads to perinatal...
SEC23B is one of two vertebrate paralogs of SEC23, a key component of the coat protein complex II vesicles. Complete deficiency of SEC23B in mice leads to perinatal death caused by massive degeneration of professional secretory tissues. However, functions of SEC23B in postnatal mice and outside professional secretory tissues are unclear. In this study, we generated a Sec23b KO mouse and a knockin (KI) mouse with the E109K mutation, the most common human mutation in congenital dyserythropoietic anemia type II patients. We found that E109K mutation led to decreases in SEC23B levels and protein mislocalization. However, Sec23b mice showed no obvious abnormalities. Sec23b hemizygosity (Sec23b) was partially lethal, with only half of expected hemizygous mice surviving past weaning. Surviving Sec23b mice exhibited exocrine insufficiency, increased endoplasmic reticulum stress and apoptosis in the pancreas, and phenotypes consistent with chronic pancreatitis. Sec23b mice had mild to moderate anemia without other typical congenital dyserythropoietic anemia type II features, likely resulting from exocrine insufficiency. Moreover, Sec23b mice exhibited severe growth restriction accompanied by growth hormone (GH) insensitivity, reminiscent of Laron syndrome. Growth restriction is not associated with hepatocyte-specific Sec23b deletion, suggesting a nonliver origin of this phenotype. We propose that inflammation associated with chronic pancreatic deficiency may explain GH insensitivity in Sec23b mice. Our results reveal a genotype-phenotype correlation in SEC23B deficiency and indicate that pancreatic acinar is most sensitive to SEC23B deficiency in adult mice. The Sec23b mice provide a novel model of chronic pancreatitis and growth retardation with GH insensitivity.
Topics: Anemia, Dyserythropoietic, Congenital; Animals; Mice; Mutation, Missense; Pancreatitis, Chronic; Phenotype; Vesicular Transport Proteins
PubMed: 34954140
DOI: 10.1016/j.jbc.2021.101536