Pathogenic/likely pathogenic variants in the SHOX, GHR and IGFALS genes among Indian children with idiopathic short stature

Homozygous 6-bp deletion of IGFALS in a prepubertal boy with short stature

Biallelic IGFALS variants lead to acid‒labile subunit (ALS) deficiency characterized by growth hormone resistance with or without delayed puberty. Here, we report a prepubertal boy with a homozygous 2-amino acid deletion within the fourth N-glycosylation motif (c.1103_1108del, p.N368_S370delinsT) associated with parental consanguinity. He showed short stature consistent with ALS deficiency. This case expands the mutation spectrum of IGFALS to include the elimination of only one N-glycosylation motif of ALS.

Endocrine and cellular physiology and pathology of the insulin-like growth factor acid-labile subunit

The acid-labile subunit (ALS) of the insulin-like growth factor (IGF) binding protein (IGFBP) complex, encoded in humans by IGFALS, has a vital role in regulating the endocrine transport and bioavailability of IGF-1 and IGF-2. Accordingly, ALS has a considerable influence on postnatal growth and metabolism. ALS is a leucine-rich glycoprotein that forms high-affinity ternary complexes with IGFBP-3 or IGFBP-5 when they are occupied by either IGF-1 or IGF-2. These complexes constitute a stable reservoir of circulating IGFs, blocking the potentially hypoglycaemic activity of unbound IGFs. ALS is primarily synthesized by hepatocytes and its expression is lower in non-hepatic tissues. ALS synthesis is strongly induced by growth hormone and suppressed by IL-1β, thus potentially serving as a marker of growth hormone secretion and/or activity and of inflammation. IGFALS mutations in humans and Igfals deletion in mice cause modest growth retardation and pubertal delay, accompanied by decreased osteogenesis and enhanced adipogenesis. In hepatocellular carcinoma, IGFALS is described as a tumour suppressor; however, its contribution to other cancers is not well delineated. This Review addresses the endocrine physiology and pathology of ALS, discusses the latest cell and proteomic studies that suggest emerging cellular roles for ALS and outlines its involvement in other disease states.

Therapeutic efficacy of recombinant human growth hormone in children with different etiologies of dwarfism from a pharmacoeconomic point of view

Treatment outcomes for different causes of childhood dwarfism vary widely, and there are no studies on the economic burden of treatment in relation to outcomes. This paper compared the efficacy and healthcare costs per unit height of recombinant human growth hormone (rhGH) for the treatment of growth hormone deficiency (GHD) and idiopathic short stature (ISS) with a view to providing a more cost-effective treatment option for children. We retrospectively analyzed 117 cases (66 cases of GHD and 51 cases of ISS) of short-stature children who first visited Weifang People's Hospital between 2019.1 and 2022.1 and were treated with rhGH for 1 to 3 years to track the treatment effect and statistically analyzed by using paired t tests, non-parametric tests, and chi-square tests, to evaluate the efficacy of rhGH treatment for GHD and ISS children and the medicinal cost. The annual growth velocity (GV) of children with GHD and ISS increased the fastest during 3 to 6 months after treatment and then gradually slowed down. The GV of the GHD group was higher than that of the ISS group from 0 to 36 months after treatment (P < .05 at 3, 6, 9, and 12 months); the height standard deviation scores (HtSDS) of the children in the GHD and ISS groups increased gradually with the increase of the treatment time, and the changes in the height standard deviation scores (ΔHtSDS) of the GHD group were more significant than those of the ISS group (P < .05 at 3, 6, 9, and 12 months). (2) The medical costs in the pubertal group for a 1-cm increase in height were higher than those of children in the pre-pubertal group at the same stage (3 to 24 months P < .05). The longer the treatment time within the same group, the higher the medical cost of increasing 1cm height. RhGH is effective in treating children with dwarfism to promote height growth, and the effect on children with GHD is better than that of children with ISS; the earlier the treatment time, the lower the medical cost and the higher the comprehensive benefit.

[Effect of recombinant human growth hormone on serum Klotho and fibroblast growth factor 23 in children with idiopathic short stature]

OBJECTIVES

To investigate the changes in the serum levels of Klotho, fibroblast growth factor 23 (FGF23), and insulin-like growth factor-1 (IGF-1) in children with idiopathic short stature (ISS) before and after recombinant human growth hormone (rhGH) treatment, as well as the correlation of Klotho and FGF23 with the growth hormone (GH)/IGF-1 growth axis in these children.

METHODS

A prospective study was conducted on 33 children who were diagnosed with ISS in the Department of Pediatrics, Hebei Provincial People's Hospital, from March 10, 2021 to December 1, 2022 (ISS group). Twenty-nine healthy children, matched for age and sex, who attended the Department of Child Healthcare during the same period, were enrolled as the healthy control group. The children in the ISS group were treated with rhGH, and the serum levels of Klotho, FGF23, and IGF-1 were measured before treatment and after 3, 6, and 9 months of treatment. A correlation analysis was conducted on these indexes.

RESULTS

There were no significant differences in the serum levels of IGF-1, Klotho, and FGF23 between the ISS and healthy control groups (P>0.05). The serum levels of Klotho, FGF23, and IGF-1 increased significantly in the ISS group after 3, 6, and 9 months of rhGH treatment (P<0.05). In the ISS group, Klotho and FGF23 levels were positively correlated with the phosphate level before treatment (P<0.05). Before treatment and after 3, 6, and 9 months of rhGH treatment, the Klotho level was positively correlated with the IGF-1 level (P<0.05), the FGF23 level was positively correlated with the IGF-1 level (P<0.05), and the Klotho level was positively correlated with the FGF23 level (P<0.05), while Klotho and FGF23 levels were not correlated with the height standard deviation of point (P>0.05).

CONCLUSIONS

The rhGH treatment can upregulate the levels of Klotho, FGF23, and IGF-1 and realize the catch-up growth in children with ISS. Klotho and FGF23 may not directly promote the linear growth of children with ISS, but may have indirect effects through the pathways such as IGF-1 and phosphate metabolism. The consistent changes in Klotho, FGF23 and IGF-1 levels show that there is a synergistic relationship among them in regulating the linear growth of ISS children.

Novel heterozygous mutation in the SHOX gene leading to familial idiopathic short stature: A case report and literature review

BACKGROUND

The pathogenic mutation of short stature homeobox (SHOX) gene is one of the main genetic causes of short stature in children, with an incidence rate of 1/1000~1/2000 and the main clinical manifestations are short stature and (or) limb skeletal abnormalities. SHOX gene mutations are mostly large deletions of regulatory sequence genes, while exon mutations are relatively rare. The pathogenic rate of mutations occurring in exon 5 is only 1/50 000~1/100 000. This study reviewed the clinical data of a child with SHOX gene mutation in exon 5, and analyzed the clinical phenotype, pathogenesis, diagnosis, treatment and prognosis of SHOX gene mutation in combination with relevant literature at home and abroad.

CASE PRESENTATION

The patient was an 8-year-old girl with a height of 105.2 cm (-4.31 standard deviations). Her sitting height/height ratio was 56.8% (>55.5%), and she exhibited high-arched palate, irregular dentition, micrognathia, short fingers, and a normal growth hormone stimulation test. Whole-exome sequencing was performed, and Sanger sequencing was used for site validation. The sequencing results revealed a heterozygous mutation of c.577G > A in exon 5 of the SHOX gene, inherited from the father. The clinical symptoms of the proband were consistent with the phenotype of short stature idiopathic familial associated with SHOX gene mutations. The father, grandfather, uncle, and sister of the proband all had the c.577G > A heterozygous mutation. Therefore, the clinical diagnosis was childhood short stature caused by SHOX gene defects. The SHOX: c.577G > A mutation is likely to be the genetic etiology of familial idiopathic short stature in this family, and this novel mutation enriches the mutation spectrum of the SHOX gene.

CONCLUSION

This is the first case report of familial idiopathic dwarfism caused by mutation at the c.577G > A locus of exon 5 of SHOX gene in the world. This novel mutation enriches the mutation spectrum of the SHOX gene. It is important to emphasize genetic testing, including the SHOX gene, in patients with familial idiopathic short stature and to provide timely growth hormone therapy to individuals with short stature caused by SHOX gene mutations in order to improve their adult height.

LCN2 is a new diagnostic biomarker and potential therapeutic target in idiopathic short stature

Idiopathic short stature (ISS) is the most common paediatric endocrine disease. However, the underlying pathology of ISS remains unclear. Currently, there are no effective diagnostic markers or therapeutic strategies available for ISS. In this study, we aimed to identify differential plasma protein expression and novel biomarkers in patients with ISS, and elucidate the biological functions of candidate proteins in ISS pathogenesis. Four specimen pairs from four ISS children and age‐/sex‐matched control individuals were subjected to proteomics analysis, and 340 samples of children with a mean age 9.73 ± 0.24 years were utilized to further verify the differentially expressed proteins by enzyme‐linked immunosorbent assay (ELISA). The receiver‐operating characteristic (ROC) curve and the area under the ROC curve (AUC) were plotted. A total of 2040 proteins were identified, of which 84 were differentially expressed. In vitro and in vivo experiments confirmed the biological functions of these candidate proteins. LCN2 overexpression in ISS was verified using ELISA. Meanwhile, LCN2 showed high sensitivity and specificity in discriminating children with ISS from those with growth hormone deficiency, precocious puberty and normal control individuals. The upregulated expression of LCN2 not only suppressed food intake but also impaired chondrocyte proliferation and bone growth in chondrocytes and rats. As a result, the rats presented a short‐stature phenotype. Subsequently, we found that bone growth inhibition recovered after LCN2 overexpression was stopped in immature rats. To our knowledge, this is the first study to report that LCN2 may be a significant target for ISS diagnosis and treatment.

Clinical impact of variants in non-coding regions of SHOX - Current knowledge

The short stature homeobox-containing (SHOX) is the most frequently analysed gene in patients classified as short stature patients (ISS) or diagnosed with Leri-Weill dyschondrosteosis (LWD), Langer mesomelic dysplasia (LMD), or Madelung deformity (MD). However, clinical testing of this gene focuses primarily on single nucleotide variants (SNV) in its coding sequences and copy number variants (CNV) overlapping SHOX gene. This review summarizes the clinical impact of variants in noncoding regions of SHOX. RECENT FINDINGS: CNV extending exclusively into the regulatory elements (i.e., not interrupting the coding sequence) are found more frequently in downstream regulatory elements of SHOX. Further, duplications are more frequent than deletions. Interestingly, downstream duplications are more common than deletions in patients with ISS or LWD but no such differences exist for upstream CNV. Moreover, the presence of specific CNVs in the patient population suggests the involvement of additional unknown factors. Some of its intronic variants, notably NM_000451.3(SHOX):c.-9delG and c.-65C>A in the 5'UTR, have unclear clinical roles. However, these intronic SNV may increase the probability that other CNV will arise de novo in the SHOX gene based on homologous recombination or incorrect splicing of mRNA. SUMMARY: This review highlights the clinical impact of noncoding changes in the SHOX gene and the need to apply new technologies and genotype-phenotype correlation in their analysis.

Exploring the genetic causes of isolated short stature. What has happened to idiopathic short stature?

Statural growth is underpinned by development of the growth plate during the process of endochondral ossification, which is strongly regulated by numerous local factors (intracellular, paracrine and extracellular matrix factors) and systemic factors (nutrition, hormones, proinflammatory cytokines and extracellular fluids). This explains why growth retardation can be associated with numerous pathologies, particularly genetic syndromes, hormonal or inflammatory conditions, or gastrointestinal disorders having a nutritional impact. However, in most cases (80%), no specific aetiology is found after clinical investigation and conventional additional tests have been carried out. In such cases, "idiopathic" short stature is diagnosed, which includes patients presenting with constitutional delay of growth and development and familial short stature, but also patients with very subtle constitutional skeletal dysplasia which are not easily identifiable. In recent years, new methods of genetic investigation (e.g. gene panels, exome or genome sequencing) have made it possible to identify many genetic variants associated with apparently isolated short stature. Indeed, it is still difficult to estimate the proportion of patients presenting with idiopathic short stature for which a molecular diagnosis of monogenic conditions could be made. This estimate varies hugely depending on the thoroughness of the clinical, laboratory and radiological assessments performed prior to molecular analysis, since retrospective analysis of positive cases usually reveals subtle signs of underlying syndromes or rare skeletal disorders. Molecular diagnosis in children is important to be able to offer genetic counselling and to organise patient management. Moreover, improved understanding of the molecular basis of these cases of short stature opens up numerous possibilities for more specific treatments targeting the growth plate. © 2022 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Analysis of Prevalence, Influencing Factors, and Countermeasures of Short Stature in Children and Adolescents Aged 6∼14 in Furong District, Changsha City, in 2020

In recent years, children's and adolescents' growth and development issues have received increasing attention with the socioeconomic development. The etiology of child short stature involves heredity, race, sex, nutrition, and a variety of endocrine hormones, which is very complex. The age of 6∼14 is the key period of children's development. Understanding the height characteristics, the prevalence of short stature, and its influencing factors at this stage and formulating preventive measures as soon as possible are conducive to improving the average height of children and reducing the incidence of short stature. In this study, cluster sampling was used to select 56,865 children and adolescents aged 6∼14 years old from 40 primary and secondary schools in Furong District of Changsha City, and the height of each child and adolescent was measured. The results showed that the overall crude prevalence of short stature in children aged 6∼14 in Furong District of Changsha is 2.82%. Growth hormone level <10 μg/L, pubertal retardation, familial short stature, low egg intake, and intrauterine growth retardation are independent risk factors affecting the occurrence of short stature. In order to improve the status quo of short stature of children aged 6∼14 in Furong District, Changsha City, targeted intervention should be strengthened for people with combined high risk factors.

Genetic causes of growth hormone insensitivity beyond GHR

Growth hormone insensitivity (GHI) syndrome, first described in 1966, is classically associated with monogenic defects in the GH receptor (GHR) gene which result in severe post-natal growth failure as consequences of insulin-like growth factor I (IGF-I) deficiency. Over the years, recognition of other monogenic defects downstream of GHR has greatly expanded understanding of primary causes of GHI and growth retardation, with either IGF-I deficiency or IGF-I insensitivity as clinical outcomes. Mutations in IGF1 and signaling component STAT5B disrupt IGF-I production, while defects in IGFALS and PAPPA2, disrupt transport and release of circulating IGF-I, respectively, affecting bioavailability of the growth-promoting IGF-I. Defects in IGF1R, cognate cell-surface receptor for IGF-I, disrupt not only IGF-I actions, but actions of the related IGF-II peptides. The importance of IGF-II for normal developmental growth is emphasized with recent identification of defects in the maternally imprinted IGF2 gene. Current application of next-generation genomic sequencing has expedited the pace of identifying new molecular defects in known genes or in new genes, thereby expanding the spectrum of GH and IGF insensitivity. This review discusses insights gained and future directions from patient-based molecular and functional studies.

A Novel Diagnostic Predictive Model for Idiopathic Short Stature in Children

OBJECTIVE

Idiopathic short stature (ISS), an endocrine-related disease, is difficult to diagnose. Previous studies have shown that many children with some inflammation-related diseases often have short stature, but whether inflammation is the underlying mechanism of ISS has not been studied. Here, we attempt to explore the role of inflammation in the occurrence and development of ISS and to demonstrate an available clinical diagnostic model of ISS.

METHODS

Frozen serum samples were collected from ISS patients (n = 4) and control individuals (n = 4). Isobaric tags for relative and absolute quantitation (iTRAQ) combined with LC-MS/MS analysis were applied to quantitative proteomics analysis. To assess clusters of potentially interacting proteins, functional enrichment (GO and KEGG) and protein-protein interaction network analyses were performed, and the crucial proteins were detected by Molecular Complex Detection (MCODE). Furthermore, serum levels of two selected proteins were measured by ELISA between ISS patients (n = 80) and controls (n = 80). In addition, experiments in vitro were used to further explore the effects of crucial proteins on endochondral ossification.

RESULTS

A total of 437 proteins were quantified, and 84 DEPs (60 upregulated and 24 downregulated) were identified between patients with ISS and controls. Functional enrichment analysis showed that the DEPs were primarily enriched in blood microparticle, acute inflammatory response, protein activation cascade, collagen-containing extracellular matrix, platelet degranulation, etc. According to the results of top 10 fold change DEPs and MCODE analysis, C1QA and C1QB were selected to further experiment. The expression levels of C1QA and C1QB were validated in serum samples. Based on the logistic regression analysis and ROC curve analysis, we constructed a novel diagnostic model by serum levels of C1QA and C1QB with a specificity of 91.2% and a sensitivity of 75% (AUC = 0.900, p <0.001). Finally, the western blotting analysis confirmed the expression levels of OCN, OPN, RUNX2, and Collagen X were downregulated in chondrocytes, and the outcome of Collagen II was upregulated.

CONCLUSION

Our study is the first to demonstrate the significant role of inflammation in the development of ISS. In addition, we identify C1QA and C1QB as novel serum biomarkers for the diagnosis of ISS.

Spectrum of amyloglucosidase mutations in Asian Indian patients with Glycogen storage disease type III

Glycogen storage disease type III (GSD III) is a rare autosomal recessive inborn error of glycogen degradation pathway due to deficiency or reduced activity of glycogen debranching enzyme (GDE) that results in accumulation of abnormal glycogen in the liver, muscle, and heart. The cardinal hallmarks are hepatomegaly, fasting hypoglycemia, seizures, growth retardation, progressive skeletal myopathy, and cardiomyopathy in few. To date, 258 mutations in amyloglucosidase (AGL) gene have been identified worldwide. However, the mutation spectrum in the Asian Indian region is yet to be well characterized. We investigated 24 patients of Asian origin from 21 unrelated families with a provisional diagnosis of GSD III based on clinical and biochemical criteria. Molecular diagnosis was assessed by bidirectional sequencing and the impact of novel missense variants on the tertiary (three-dimensional) structure of GDE was evaluated by molecular modeling approach. Eighteen different pathogenic variants were identified, out of which 78% were novel. Novel variants included five nonsense, three small duplications and two small deletions, a splice site variant, and three missense variants. Variations in Exons 4, 14, 19, 24, 27, and 33 accounted for 61% of the total pathogenic variants identified and Allele p.Gly798Alafs*3 showed a high allele frequency of 11%. Molecular modeling study of novel pathogenic missense variants indicated the probable underlying molecular mechanism of adverse impact of variations on the structure and catalytic function of human GDE. Our study is the first large study on GSD III from the Asian subcontinent, which further expands the mutation spectrum of AGL.