Laron Syndrome: A Tale of Two Siblings.

Primary growth hormone (GH) resistance or growth hormone insensitivity syndrome, also called Laron syndrome, is a hereditary disease caused by mutations in the GH receptor or in the post-receptor signaling pathway. This disorder is characterized by postnatal growth failure resembling GH deficiency. Differentiating the two conditions is necessary. We present the cases of two siblings, a 16-year-old female and a 9-year-old male, born from a consanguineous union. Both had normal birth weights with subsequent severe short stature and delayed teeth eruption, with no features suggestive of any systemic illness. Serum insulin-like growth factor 1 (IGF1) and insulin-like growth factor binding protein 3 (IGFBP3) were both low. Suspecting GH deficiency, provocative testing with clonidine was done revealing peak growth hormone >40 ng/mL in both patients. In view of low IGF1 and IGFBP3 and high GH on stimulation, IGF1 generation test was done for both siblings, with values supporting the diagnosis of GH insensitivity or Laron syndrome.

A Recurrent Mutation in Growth Hormone Receptor (GHR) Gene Underlying Laron-type Dwarfism in a Pakistani Family.

Laron syndrome (LS) is a rare autosomal recessively segregating disorder of severe short stature. The condition is characterized by short limbs, delayed puberty, hypoglycemia in infancy, and obesity. Mutations in growth hormone receptor (GHR) have been implicated in LS; hence, it is also known as growth hormone insensitivity syndrome (MIM-262500). Here we represent a consanguineous Pakistani family in which three siblings were afflicted with LS. Patients had rather similar phenotypic presentations marked with short stature, delayed bone age, limited extension of elbows, truncal obesity, delayed puberty, childish appearance, and frontal bossing. They also had additional features such as hypo-muscularity, early fatigue, large ears, widely-spaced breasts, and attention deficit behavior, which are rarely reported in LS. The unusual combination of the features hindered a straightforward diagnosis and prompted us to first detect the regions of shared homozygosity and subsequently the disease-causing variant by next generation technologies, like SNP genotyping and exome sequencing. A homozygous pathogenic variant c.508G>C (p.(Asp170His)) in GHR was detected. The variant is known to be implicated in LS, supporting the molecular diagnosis of LS. Also, we present detailed clinical, hematological, and hormonal profiling of the siblings.

Challenges in the care of individuals with severe primary insulin-like growth factor-I deficiency (SPIGFD): an international, multi-stakeholder perspective.

BACKGROUND: Severe primary insulin-like growth factor-I (IGF-I) deficiency (SPIGFD) is a rare growth disorder characterized by short stature (standard deviation score [SDS] ≤ 3.0), low circulating concentrations of IGF-I (SDS ≤ 3.0), and normal or elevated concentrations of growth hormone (GH). Laron syndrome is the best characterized form of SPIGFD, caused by a defect in the GH receptor (GHR) gene. However, awareness of SPIGFD remains low, and individuals living with SPIGFD continue to face challenges associated with diagnosis, treatment and care. OBJECTIVE: To gather perspectives on the key challenges for individuals and families living with SPIGFD through a multi-stakeholder approach. By highlighting critical gaps in the awareness, diagnosis, and management of SPIGFD, this report aims to provide recommendations to improve care for people affected by SPIGFD globally. METHODS: An international group of clinical experts, researchers, and patient and caregiver representatives from the SPIGFD community participated in a virtual, half-day meeting to discuss key unmet needs and opportunities to improve the care of people living with SPIGFD. RESULTS: As a rare disorder, limited awareness and understanding of SPIGFD amongst healthcare professionals (HCPs) poses significant challenges in the diagnosis and treatment of those affected. Patients often face difficulties associated with receiving a formal diagnosis, delayed treatment initiation and limited access to appropriate therapy. This has a considerable impact on the physical health and quality of life for patients, highlighting a need for more education and clearer guidance for HCPs. Support from patient advocacy groups is valuable in helping patients and their families to find appropriate care. However, there remains a need to better understand the burden that SPIGFD has on individuals beyond height, including the impact on physical, emotional, and social wellbeing. CONCLUSIONS: To address the challenges faced by individuals and families affected by SPIGFD, greater awareness of SPIGFD is needed within the healthcare community, and a consensus on best practice in the care of individuals affected by this condition. Continued efforts are also needed at a global level to challenge existing perceptions around SPIGFD, and identify solutions that promote equitable access to appropriate care. Medical writing support was industry-sponsored.

Identification and In Vitro Functional Verification of Two Novel Mutations of GHR Gene in the Chinese Children with Laron Syndrome.

Purpose: Laron syndrome (LS) is a severe growth disorder caused by GHR gene mutation or post-receptor pathways defect. The clinical features of these patients collected in our present study were summarized, GHR gene variants were investigated and further in vitro functional verification was carried out. Methods: Four patients with LS were collected, their clinical characteristics were summarized, genomic DNA was extracted, and GHR gene was amplified and sequenced. GHR wild type (GHR-WT) and mutant GHR expression plasmids were constructed, and transiently transfected into HepG2 cells and HEK293T cells to observe the subcellular distribution of the GHR protein by immunofluorescence and to determine the expression of GHR and its post-receptor signaling pathway changes by Western blotting. Results: All of the four patients were male, and the median height was -4.72 SDS. Four GHR gene variants including c.587A>C (p.Y196S), c.766C>T (p.Q256*), c.808A>G (p.I270V) and c.1707-1710del (p.E570Afs*30) were identified, and the latter two were novel mutations. The results of mutant GHR plasmids transfection experiments and immunofluorescence assay showed that the subcellular distribution of GHR-Q256* and GHR-E570Afs*30 mutant proteins in HepG2 and HEK293T cells presented with a unique ring-like pattern, gathering around the nucleus, while GHR-Y196S mutant protein was evenly distributed on HepG2 cell membrane similar to GHR-WT. The GHR protein levels of HepG2 cells transiently transfected with GHR-Y196S, GHR-Q256* and GHR-E570Afs*30 were all significantly lower when compared with cells transfected with GHR-WT (P<0.05). Further mutant GHR post-receptor signal transduction investigation demonstrated that GH induced phosphorylated STAT5 levels of HepG2 cells transfected with three mutant plasmids were all significantly decreased in comparison with that of GHR-WT (P<0.05). Conclusions: Two novel GHR gene mutations (I270V and E570Afs*30) were found in our patients with LS. GHR mutations influenced the subcellular distribution and GHR protein levels, then led to the impaired post-receptor signal transduction, suggesting that the GHR mutations contributed to the pathological condition of LS patients.

A 42-Year-Old Woman with Untreated Growth Hormone Insensitivity, Diabetic Retinopathy, and Gene Sequencing Identifies a Variant of Laron Syndrome.

BACKGROUND Growth hormone insensitivity and reduced levels of insulin-like growth factor-1 (IGF-1) are associated with metabolic syndrome that includes obesity, hyperglycemia, type 2 diabetes mellitus, and dyslipidemia. Laron syndrome is a rare autosomal recessive condition associated with insensitivity to growth hormone that results in short stature and metabolic syndrome and is usually diagnosed in childhood. This report is of a 42-year-old Mexican woman with untreated growth hormone insensitivity and diabetic retinopathy, in whom gene sequencing supported the identification of a variant of Laron syndrome. CASE REPORT A 42-year-old Mexican woman with untreated growth hormone insensitivity, metabolic syndrome, and type 2 diabetes mellitus was diagnosed with cataracts, severe retinopathy and hearing loss. She was investigated for genetic causes of reduction in IGF-1. Next-generation sequencing (NGS) showed genetic changes in the growth hormone and IGF-1 axis. The patient's phenotype and genetic changes were consistent with Laron syndrome. CONCLUSIONS The early detection of reduced IGF-1 and identification of the cause of growth hormone insensitivity require international consensus on the approach to diagnosis and treatment methods, including effective IGF-1 replacement therapy. Early diagnosis may reduce the clinical consequences of complications that include short stature the development of metabolic syndrome, type 2 diabetes mellitus, and retinopathy.

Laron syndrome related to homozygous growth hormone receptor c.784>C mutation in a patient with hypoplastic pulmonary arteries.

Laron syndrome, also known as growth hormone insensitivity, is an autosomal recessive disorder characterised by short stature due to mutations or deletions in the growth hormone receptor (GHR), leading to congenital insulin-like growth factor 1 (IGF1) deficiency. Cardiac abnormalities, such as patent ductus arteriosus or peripheral vascular disease are rare in patients with Laron syndrome, but cardiac hypertrophy has been observed after IGF1 therapy. In this report, we present a 10-year-and-5-month-old girl with severe peripheral-type pulmonary artery hypoplasia and Laron syndrome related to homozygous GHR c.784>C mutation.

Cardiac examination in children with Laron syndrome undergoing mecasermin therapy.

BACKGROUND: Laron syndrome (LS), which can be defined as primary growth hormone resistance or insensitivity, is a rare genetic disease inherited by an autosomal recessive trait. Although it is undistinguishable from growth hormone deficiency, LS has high levels of growth hormone, but insulin-like growth factor (IGF-1) cannot be synthesized. Mecasermin treatment is the only option for the patients who suffer from LS. This study aims to research cardiac findings of children with LS, who receive treatment with mecasermin. METHODS: The study enrolled five children four males and one female, 4 M/1 F with LS, two of whom were siblings with a mean age of 6.3±2.1 years, a body weight of 13.36±4.74 kg, a height of 88±8.7 cm, and a body mass index (BMI) of 16.47±3.35. Their demographic data were obtained from their family and files. The children received mecasermin via subcutaneous injection at 0.04-0.12 µg/kg doses twice per day. The duration of mecasermin treatment was 8-53 months. All of them were examined clinically by electrocardiogram and echocardiogram. RESULTS: Their cardiac examinations were normal, except for one case, who had systolic murmur at cardiac auscultation. Arrhythmia was not observed on their electrocardiograms. The echocardiograms did not show a significant congenital cardiac anomaly. Their cardiac measure and functions were within normal ranges. The echocardiogram of the child with the murmur showed mitral and tricuspid insufficiency. The Doppler images showed pulmonary hypertension findings. These findings were proven by angiography. The vasoreactivity test results of that patient were negative. No reason could be found for the observed pulmonary hypertension. We diagnosed this finding as a primary pulmonary hypertension and Bosentan therapy was started. CONCLUSIONS: In this study, we showed that cardiac findings were consistent with previous studies. To the best of our knowledge, the observed pulmonary hypertension in children with LS, who received treatment with or without mecasermin, is reported for first time in the literature.

Compound heterozygosity for two GHR missense mutations in a patient affected by Laron Syndrome: a case report.

BACKGROUND: Mutations localized in the Growth Hormone Receptor (GHR) gene are often associated with the pathogenesis of Laron Syndrome, an autosomal recessive hereditary disorder characterized by severe growth retardation. Biochemically, patients present normal to high circulating GH levels, in presence of very low or undetectable IGF-I levels, which do not rise after rhGH treatment. CASE PRESENTATION: We describe the case of a 3.8 years old girl with symmetrical short stature (-3.76 SDS), low IGF-1 and IGFBP-3, in presence of normal GH levels. Parents were not relatives and there was no family history of short stature. During the second day of birth, she developed severe hypoglycaemia that required glucose infusion. She presented frontal bossing and depressed nasal bridge. IGF-1 generation test showed no response, suggesting a GH resistance evidence. In the hypothesis of Laron Syndrome, we decided to perform a molecular analysis of Growth Hormone Receptor (GHR) gene. This analysis demonstrated that the patient was compound heterozygote for two missense mutations. CONCLUSIONS: GHR gene mutations are a well demonstrated cause of GH insensitivity. In heterozygous patients, probably the normal stature may be achieved by a compensatory mechanism of GH secretion or signalling. On the contrary, in homozygous or compound heterozygous patients these compensatory mechanisms are inadequate, and short stature may be the consequence.

[Laron syndrome: Presentation, treatment and prognosis]. / Syndrome de Laron : aspects diagnostiques, thérapeutiques et pronostiques.

Laron syndrome is a rare cause of short stature due to an abnormality of growth hormone receptor (GHR). It is characterized by poor phenotype-genotype correlation and geographic predilection essentially in the Mediterranean rim, the Middle East and Indian subcontinent. This syndrome corresponds to an endogenous and exogenous complete insensitivity of GH and manifests by early hypoglycemia, an extremely severe short stature and dysmorphic features contrasting with high levels of circulating GH. To date, treatment with recombinant IGF1 is the only treatment option that has improved the terrible prognosis in these patients but does not actually realize the conditions for genuine replacement therapy.

Effects of GH/IGF-I Axis on Retinal Vascular Morphology: Retinal Vascular Characteristics in a Clinical Setting with Severe IGF-I Deficiency.

BACKGROUND: The purpose of this study was to assess retinal vascular characteristics of patients with Laron syndrome (LS) as a genetic model of IGF-I deficiency before and after rhIGF1/IGFBP3 treatment and to compare them with healthy controls. METHODS: A total of 28 subjects (11 LS, and 17 controls) were enrolled. Patients with LS received combined rhIGF1/rhIGFBP3 1-2 mg/kg/d in a single dose and digital fundus imaging was performed. The number of branching points and tortuosity of retinal vessels were studied. Pre- and post-treatment findings were compared with each other and with controls. RESULTS: The number of branching points was significantly lower in patients with LS in comparison to controls (12.73 ± 3.41, and 17.47 ± 5.82 respectively, p = 0.012). This difference persisted after treatment (12.09 ± 2.66 post-treatment LS versus controls, p = 0.017). Tortuosity indices of nasal arteries (NA) were significantly less in LS than that of controls (upper NA 1.07 ± 0.04 and 1.12 ± 0.06 respectively p = 0.022; lower NA 1.07 ± 0.03 and 1.13 ± 0.07 respectively, p = 0.004). This difference also persisted following treatment (p < 0.05). Remaining vessels did not differ in tortuosity index. There was no significant difference of tortuosity index and number of branching points before and after treatment in patients with LS. CONCLUSION: Retinal vascular development may be adversely affected in the setting of severe IGF-I deficiency confirming a major role for GH/IGF-I axis during retinal vascular development in humans antenatally. Resolution of IGF-I deficiency following birth using rhIGF1, however, may not reverse these changes, suggesting that IGF-I may be necessary but insufficient by itself for postnatal angiogenesis.

A half-century of studies of growth hormone insensitivity/Laron syndrome: A historical perspective.

UNLABELLED: A growth hormone (GH) dependent substance responsible for sulfate uptake by costal cartilage of hypophysectomized rats, labeled sulfation factor, was reported in 1957. In 1962 the radioimmunoassay for GH was described. The clinical picture of severe GH deficiency but with high serum concentrations of GH was reported in 3 siblings in 1966 and followed by a 1968 report of 22 patients belonging to 14 consanguineous oriental Jewish families in Israel. Defective sulfation factor generation was demonstrated in 15 of these individuals and in a 1971 report; FFA response to IV GH and growth response to GH injections suggested competitive saturation of peripheral tissue receptors by an abnormal GH. However, studies published in 1973 demonstrated normal fractionation of their circulating GH, and normal binding of GH from 22 patients to various antisera used for radioimmunoassay. In 1976, the Israeli investigators reported that circulating GH from 7 patients reacted normally in the recently developed radioreceptor assay for GH. In 1984, using hepatic microsome pellets, they demonstrated that the defect was a failure of GH binding to receptors. Characterization of the human GH receptor (GHR) gene, reported in 1989, included the initial description of a genetic defect of the GHR in 2 of 9 Israeli patients. At about the same time began the identification in Ecuador of what was to become the largest population of GH insensitivity in the world, ~100 individuals, and the only substantial population with a common mutation of the GH receptor. Treatment studies with recombinant IGF-I began in 1990. Growth response was modest compared to that of GH treated GH deficient subjects. The spectrum of GH insensitivity has expanded beyond GH receptor deficiency to include postreceptor abnormalities: IGF-I gene mutation (1996); IGF-I receptor mutation (2003); signal transducer and activator of transcription 5b mutation (2003); and mutation of the GH-dependent acid labile subunit (2004). CONCLUSION: Rare conditions of GH insensitivity caused by GH receptor and postreceptor abnormalities have provided insights into the processes of growth, body composition, and metabolism.

Growth hormone insensitivity: diagnostic and therapeutic approaches.

INTRODUCTION: Growth hormone resistance defines several genetic (primary) and acquired (secondary) pathologies that result in completely or partially interrupted activity of growth hormone. An archetypal disease of this group is the Laron-type dwarfism caused by mutations in growth hormone receptors. The diagnosis is based on high basal levels of growth hormone, low insulin like growth factor-I (IGF-1) level, unresponsiveness to IGF generation test and genetic testing. Recombinant IGF-1 preparations are used in the treatment CONCLUSION: In this article, clinical characteristics, diagnosis and therapeutic approaches of the genetic and other diseases leading to growth hormone insensitivity are reviewed.

The E180splice mutation in the GHR gene causing Laron syndrome: witness of a Sephardic Jewish exodus from the Iberian Peninsula to the New World?

Laron syndrome (LS) is a genetic disorder caused by mutations in the growth hormone receptor (GHR) gene. The most frequent GHR mutation is E180splice (rs121909360), which was initially found in an inbred population of Spanish descent in Ecuador and subsequently in Israel, Brazil, Chile, and the United States. The aim of the present study is to determine if the E180splice mutation arose from a common origin. We studied 22 patients with LS from Ecuador, Israel (of Moroccan origin), Brazil, Chile, and the United States (of Mexican origin) who were homozygous for the E180splice mutation and compared them to control individuals for markers surrounding the GHR, intragenic polymorphisms, and Y-chromosome STR. An identical haplotype was found in all but one of the subjects carrying the E180splice mutation: D5S665: 150/150; D5S2082: 192/192; D5S2087: 246/246; rs6179 G/G; and rs6180 C/C. One patient differed from the others only at D5S2082 (168/192). This haplotype is rare (~1%) in control individuals and confirmed that the E180splice-associated haplotype was not derived from independent origins but represented recombination from a common ancestor. The analysis of paternal lineage markers showed that 50% belong to haplogroup R1b (found in Portugal and Spain) and 40% to haplogroups J and E (typical in the Middle East and in Eastern European Jews). The germline E180Splice mutation appears to have originated from a single common ancestor. The presence of Y-chromosome markers associated with Sephardic populations in persons harboring the E180splice mutation provides genetic evidence in support of the historical tracking of the exodus of this specific population.

Phenotypes, investigation and treatment of primary IGF-1 deficiency.

GH insensitivity, also known as primary IGF-1 deficiency (PIGFD), presents as growth failure, and in its severe form is associated with dysmorphic and metabolic abnormalities. PIGFD is caused by genetic defects in the GH-IGF-1 axis. The field of PIGFD due to mutations affecting GH action has evolved since the original description of the extreme phenotype related to homozygous GH receptor mutations over 40 years ago. A continuum of genetic, phenotypic, and biochemical abnormalities can be defined associated with clinically relevant defects in linear growth. A systematic protocol of investigation assessing Gh secretion and the IGF system will lead to a diagnosis of PIGFD. PIGFD can be effectively treated with rhIGF-1, the optimal recommended maintenance dose being 120 µg/kg twice daily by SC injection. Most therapeutic experience is in severely affected patients with the Laron syndrome phenotype, who show growth acceleration and may reach normal adult height. Further controlled studies are needed in more mildly affected subjects.

Spectrum of insulin-like growth factor deficiency.

There are eight known genetic causes of short stature characterized by low serum IGF-1 (IGF-1 deficiency, IGFD) and normal GH secretion. One of these (GHSR defect) is a form of secondary IGFD, although the GH peak in provocation tests can be normal. Bioinactive GH (GH1 mutations) can disturb GH secretion, but also GH binding and signaling. The remaining conditions are classified as primary IGFD (GH insensitivity). The clinical phenotype of GH receptor (GHR) defects is variable. Of the three GH signal transduction defects, a STAT5B defect is well established, but abnormalities in the MAPK pathway (such as PTPN11 mutations in Noonan syndrome) and NF-ĸB pathway (IĸBα mutation) may also cause IGFD. Homozygous IGFALS defects are relatively common, and lead to moderate growth failure, very low serum IGF-1 and even lower IGFBP-3, while a heterozygous IGFALS mutation decreases height by 1 SD. Most cases with a homozygous IGF1 defect are very short, microcephalic, and deaf, but heterozygous mutations may also lead to short stature. IGFD can also have a digenic or oligogenic origin. The diagnostic yield of genetic testing in children with a height <-2.5 SDS and a serum IGF-1 <-2 appears sufficient to perform genetic tests for known candidate genes.