Characterization of a novel fast-growing zebrafish: a new approach to growth hormone transgenesis.

The manipulation of the somatotropic axis, governing growth, has been a focus of numerous transgenic approaches aimed at developing fast-growing fish for research, medicine and aquaculture purposes. However, the excessively high growth hormone (GH) levels in these transgenic fish often result in deformities that impact both fish health and consumer acceptance. In an effort to mitigate these issues and synchronize exogenous GH expression with reproductive processes, we employed a novel transgenic construct driven by a tilapia luteinizing hormone (LH) promoter. This approach was anticipated to induce more localized and lower exogenous GH secretion. In this study, we characterized the growth and reproduction of these transgenic LHp-GH zebrafish using hormonal and physiological parameters. Our findings reveal that LHp-GH fish exhibited accelerated growth in both length and weight, along with a lower feed conversion ratio, indicating more efficient feed utilization, all while maintaining unchanged body proportions. These fish demonstrated higher expression levels of LH and GH in the pituitary and elevated IGF-1 levels in the liver compared to wild-type fish. An examination of reproductive function in LHp-GH fish unveiled lower pituitary LH and FSH contents, smaller follicle diameter in female gonads, and reduced relative fecundity. However, in transgenic males, neither the distribution of spermatogenesis stages nor sperm concentrations differed significantly between the fish lines. These results suggest that coupling exogenous GH expression with endogenous LH expression in females directs resource investment toward somatic growth at the expense of reproductive processes. Consequently, we conclude that incorporating GH under the LH promoter represents a suitable construct for the genetic engineering of commercial fish species, providing accelerated growth while preserving body proportions.

Case report: Long term response to growth hormone in a child with Silver-Russell syndrome-like phenotype due to a novel paternally inherited IGF2 variant.

Silver-Russell syndrome (SRS, OMIM, 180860) is a rare genetic disorder with a wide spectrum of symptoms. The most common features are intrauterine growth retardation (IUGR), poor postnatal development, macrocephaly, triangular face, prominent forehead, body asymmetry, and feeding problems. The diagnosis of SRS is based on a combination of clinical features. Up to 60% of SRS patients have chromosome 7 or 11 abnormalities, and <1% show abnormalities in IGF2 signaling pathway genes (IGF2, HMGA2, PLAG1 and CDKN1C). The underlying genetic cause remains unknown in about 40% of cases (idiopathic SRS). We report a novel IGF2 variant c.[-6-2A>G] (NM_000612) in a child with severe IUGR and clinical features of SRS and confirm the utility of targeted exome sequencing in patients with negative results to common genetic analyses. In addition, we report that long-term growth hormone treatment improves height SDS in this patient.

Identification and functional analysis of first heterozygous frameshift mutation in the GHRH gene in a Chinese boy with isolated growth hormone deficiency.

BACKGROUND: Isolated growth hormone deficiency (IGHD) is a rare genetically heterogeneous disorder caused primarily by mutations in GH1 and GH releasing hormone receptor (GHRHR). The aim of this study was to identify the molecular etiology of a Chinese boy with IGHD. METHODS: Whole-exome sequencing, sanger sequencing and bioinformatic analysis were performed to screen for candidate mutations. The impacts of candidate mutation on gene expression, intracellular localization and protein function were further evaluated by in vitro assays. RESULTS: A novel heterozygous frameshift mutation in the GHRH gene (c.91dupC, p.R31Pfs*98) was identified in a Chinese boy clinically diagnosed as having IGHD. The mutation was absent in multiple public databases, and considered as deleterious using in silico prediction, conservative analysis and three-dimensional homology modeling. Furthermore, mRNA and protein expression levels of mutant GHRH were significantly increased than wild-type GHRH (p < 0.05). Moreover, mutant GHRH showed an aberrant accumulation within the cytoplasm, and obviously reduced ability to stimulate GH secretion and cAMP accumulation in human GHRHR-expressing pituitary GH3 cells compared to wild-type GHRH (p < 0.05). CONCLUSION: Our study discovered the first loss-of function mutation of GHRH in a Chinese boy with IGHD and provided new insights on IGHD pathogenesis caused by GHRH haploinsufficiency.

Molecular diagnosis is an important indicator for response to growth hormone therapy in children with short stature.

BACKGROUND: Significant differences have been observed in the efficacy of recombinant human growth hormone (rhGH) treatment for short children. The present study aimed to identify the genetic etiology of short stature and to assess the role of molecular diagnosis in predicting responses to rhGH treatment. METHODS: A total of 407 short children were included in the present study, 226 of whom received rhGH treatment. Whole-exome sequencing (WES) was conducted on short children to identify the underlying genetic etiology. Correlations between molecular diagnosis and the efficacy of rhGH treatment were examined. RESULTS: Pathogenic or likely pathogenic mutations were identified in 86 of the 407 patients (21.1%), including 36 (41.9%) novel variants. Among the multiple pathways affecting short stature, genes involved in fundamental cellular processes (38.7%) play a larger role, especially the RAS-MAPK pathway. In general, patients without pathogenic mutations responded better to rhGH than those with mutations. Furthermore, patients with hormone signaling pathway mutations had a better response to rhGH, while those with paracrine factor mutations had a worse response to rhGH. CONCLUSIONS: This study highlights the utility of WES in identifying genetic etiology in children with short stature. Identifying likely causal mutations is an important factor in predicting rhGH response.

The Genetic Landscape of Children Born Small for Gestational Age with Persistent Short Stature.

INTRODUCTION: Among children born small for gestational age, 10-15% fail to catch up and remain short (SGA-SS). The underlying mechanisms are mostly unknown. We aimed to decipher genetic aetiologies of SGA-SS within a large single-centre cohort. METHODS: Out of 820 patients treated with growth hormone (GH), 256 were classified as SGA-SS (birth length and/or birth weight <-2 SD for gestational age and life-minimum height <-2.5 SD). Those with the DNA triplet available (child and both parents) were included in the study (176/256). Targeted testing (karyotype/FISH/MLPA/specific Sanger sequencing) was performed if a specific genetic disorder was clinically suggestive. All remaining patients underwent MS-MLPA to identify Silver-Russell syndrome, and those with unknown genetic aetiology were subsequently examined using whole-exome sequencing or targeted panel of 398 growth-related genes. Genetic variants were classified using ACMG guidelines. RESULTS: The genetic aetiology was elucidated in 74/176 (42%) children. Of these, 12/74 (16%) had pathogenic or likely pathogenic (P/LP) gene variants affecting pituitary development (LHX4, OTX2, PROKR2, PTCH1, POU1F1), the GH-IGF-1 or IGF-2 axis (GHSR, IGFALS, IGF1R, STAT3, HMGA2), 2/74 (3%) the thyroid axis (TRHR, THRA), 17/74 (23%) the cartilaginous matrix (ACAN, various collagens, FLNB, MATN3), and 7/74 (9%) the paracrine chondrocyte regulation (FGFR3, FGFR2, NPR2). In 12/74 (16%), we revealed P/LP affecting fundamental intracellular/intranuclear processes (CDC42, KMT2D, LMNA, NSD1, PTPN11, SRCAP, SON, SOS1, SOX9, TLK2). SHOX deficiency was found in 7/74 (9%), Silver-Russell syndrome in 12/74 (16%) (11p15, UPD7), and miscellaneous chromosomal aberrations in 5/74 (7%) children. CONCLUSIONS: The high diagnostic yield sheds a new light on the genetic landscape of SGA-SS, with a central role for the growth plate with substantial contributions from the GH-IGF-1 and thyroid axes and intracellular regulation and signalling.

Insulin-like growth factors and aging: lessons from Laron syndrome.

The growth hormone (GH)-insulin-like growth factor-1 (IGF1) signaling pathway emerged in recent years as a key determinant of aging and longevity. Disruption of this network in different animal species, including flies, nematodes and mouse, was consistently associated with an extended lifespan. Epidemiological analyses have shown that patients with Laron syndrome (LS), the best-characterized disease under the umbrella of the congenital IGF1 deficiencies, seem to be protected from cancer. While aging and cancer, as a rule, are considered diametrically opposite processes, modern lines of evidence reinforce the notion that aging and cancer might, as a matter of fact, be regarded as divergent manifestations of identical biochemical and cellular underlying processes. While the effect of individual mutations on lifespan and health span is very difficult to assess, genome-wide screenings identified a number of differentially represented aging- and longevity-associated genes in patients with LS. The present review summarizes recent data that emerged from comprehensive analyses of LS patients and portrays a number of previously unrecognized targets for GH-IGF1 action. Our article sheds light on complex aging and longevity processes, with a particular emphasis on the role of the GH-IGF1 network in these mechanisms.

Growth Axis Somatostatin, Growth Hormone Receptor, and Insulin-like Growth Factor-1 Genes Express and Are Affected by the Injection of Exogenous Growth Hormone in Chinemys reevesii.

In this study, to explore the effect of growth hormone changes on the related genes and regulatory roles of the turtle, PCR amplification, real-time fluorescence quantitative analysis, and enzyme cutting technology were used to clone and sequence the somatostatin (SS) gene, growth hormone receptor (GHR), and insulin-like growth factor-1 (IGF-I) sequence of Chinemys reevesii. The effects of human growth hormone on the mRNA expression of growth-axis-related genes SS, GHR, and IGF-1 in different sexes were observed. The study of the SS gene in turtles using real-time fluorescence quantitative PCR showed that the SS gene was mainly expressed in the nervous system and the digestive system, with the highest expression found in the brain, while the GHR gene and the IGF-I gene were expressed in all tissues of Chinemys reevesii. The SS gene was expressed in the brain, pituitary, liver, stomach, and intestine, with the highest expression in the brain and the lowest expression in the liver. Within 4 weeks of the injection of exogenous growth hormone, the expression level of the SS gene in the brain of both sexes first increased and then decreased, showing a parabolic trend, and the expression level of the experimental group was lower than that of the control group. After the injection of growth hormone (GH), the expression of the GHR gene in the liver of both sexes showed a significant increase in the first week, decreasing to the control group level in the second week, and then gradually increasing. Finally, a significant level of difference in the expression of the GHR gene was reached at 3 and 4 weeks. In terms of the IGF-I gene, the changing trend of the expression level in the liver was the same as that of the GHR gene. After the injection of exogenous growth hormone, although the expression of the SS gene increased the inhibition of the secretion of the GHR gene by the Reeves' turtle, exogenous growth hormone could replace the synthesis of GH and GHR, accelerating the growth of the turtle. The experiments showed that the injection of recombinant human growth hormone affects the expression of SS, GHR, and IGF-1 genes, and promotes the growth of the Reeves' turtle.

Growth hormone receptor agonists and antagonists: From protein expression and purification to long-acting formulations.

Recombinant human growth hormone (rhGH) and GH receptor antagonists (GHAs) are used clinically to treat a range of disorders associated with GH deficiency or hypersecretion, respectively. However, these biotherapeutics can be difficult and expensive to manufacture with multiple challenges from recombinant protein generation through to the development of long-acting formulations required to improve the circulating half-life of the drug. In this review, we summarize methodologies and approaches used for making and purifying recombinant GH and GHA proteins, and strategies to improve pharmacokinetic and pharmacodynamic properties, including PEGylation and fusion proteins. Therapeutics that are in clinical use or are currently under development are also discussed.

The benefit of rhGH therapy in a Chinese child with 12q14 microdeletion syndrome: a case report.

OBJECTIVES: The 12q14 microdeletion syndrome is a rare genetic condition characterized by intrauterine growth restriction, proportionate short stature, failure to thrive, and intellectual disability. Few reports have discussed the therapeutic aspect of patients with 12q14 microdeletion syndrome. Herein, we report the first case of 12q14 microdeletion patient treated with rhGH without growth hormone deficiency. CASE PRESENTATION: The patient presented with feeding difficulties during infancy, failure to thrive, intellectual disability and subtle dysmorphic facial features. The patient first visited the clinic at 5 years and 3 months, his height was 91.4 cm (-4.9 SD) and weight 10.0 kg (-2.86 SD). The growth hormone level was within the normal range. Bone radiological testing revealed no significant abnormalities. Genetic analysis identified a 6.97 Mb deletion at the chromosome 12q14.1-q14.3 region in the proband. Recombinant human growth hormone therapy was initiated, which lasted for 12 months, and the new height was 101.0 cm (-4.0 SD) and weight 12.0 kg (-3.6 SD). CONCLUSIONS: This report first showed that patient with 12q14 microdeletion, although without growth hormone deficiency, can benefit from human growth hormone therapy.

Sex-specific effects of Cre expression in Syn1Cre mice.

The Cre-loxP system has been used to generate cell-type specific mutations in mice, allowing researchers to investigate the underlying biological mechanisms of disease. However, the Cre-recombinase alone can induce phenotypes that confound comparisons among genotypes if the appropriate Cre control is not included. In this study, we characterised behavioural, morphological and metabolic phenotypes of the pan-neuronal Syn1Cre line. We found that these mice possess intact neuromuscular parameters but have reduced exploratory activity and a male-specific increase in anxiety-like behaviour. Moreover, we observed a male-specific deficit in learning and long-term memory of Syn1Cre mice that could be a result of decreased visual acuity. Furthermore, we found that over-expression of human growth hormone (hGH) from Syn1Cre results in a male-specific reduction in body weight and femur length, potentially through decreased hepatic Igf1 expression. However, metabolic characteristics of Syn1Cre mice such as glucose metabolism, energy expenditure and feeding were unaffected by the presence of Syn1Cre. In conclusion, our data demonstrate that Syn1Cre expression has effects on behavioural and morphological traits. This finding highlights the importance of including the Cre control in all comparisons, while the male-specific effects on some phenotypes highlight the importance of including both sexes.

Recombinant production of antibody antigen-binding fragments with an N-terminal human growth hormone tag in mammalian cells.

Antigen-binding fragments (Fabs) of antibodies are both key biopharmaceuticals and valuable tools for basic life science. To streamline the production of diverse Fabs by capitalizing on standard and highly optimized protein production protocols, we here explore a method to prepare recombinant Fabs as secreted fusion proteins with an N-terminal human growth hormone domain and an octa-histidine tag. These tagged Fabs can be purified with standard immobilized metal chelate affinity chromatography. We first demonstrated Fab overproduction using the rat monoclonal antibody NZ-1. Optimization of linker residues enabled the complete removal of the tags by TEV protease, leaving only two additional residues at the N-terminus of the heavy chain. We purified NZ-1 Fab at ∼4 µg/mL of culture supernatant and further confirmed that the NZ-1 Fab from the fusion protein maintained its native fold and binding affinity for target cell-surface antigens. We also showed that several other Fabs of mouse IgG1s, the major subclass in mice, could be produced with the same procedure. Our preparation method can provide greater flexibility in functional and structural modifications of target Fabs because specialized purification techniques are not necessary.

An Attempt to Identify the Medaka Receptor for Somatolactin Alpha Using a Reverse Genetics Approach.

Somatolactin alpha (SLα) is a fish-specific hormone involved in body color regulation. The growth hormone (GH) is another hormone that is expressed in all vertebrates and promotes growth. These peptide hormones act by binding to receptors (SLα receptor (SLR) and GH receptor (GHR)); however, the relationships between these ligands and their receptors vary among species. Here, we first performed phylogenetic tree reconstruction by collecting the amino-acid sequences classified as SLR, GHR, or GHR-like from bony fish. Second, we impaired SLR or GHR functions in medaka (Oryzias sakaizumii) using CRISPR/Cas9. Lastly, we analyzed SLR and GHR mutants for phenotypes to deduce their functions. Phylogenetic tree reconstruction was performed using a total of 222 amino-acid sequences from 136 species, which revealed that many GHRa and GHRb are vaguely termed as GHR or GHR-like, while showing no orthologous/paralogous relationships. SLR and GHR mutants were successfully established for phenotyping. SLR mutants exhibited premature lethality after hatching, indicating an essential role for SLR in normal growth. GHR mutations did not affect viability, body length, or body color. These results provide no evidence that either SLR or GHR functions as a receptor for SLα; rather, phylogenetically and functionally, they seem to be receptors for GH, although their (subfunctionalized) roles warrant further investigation.

Sustained secretion of human growth hormone from TheraCyte devices encapsulated with PiggyBac-engineered retinal pigment epithelium cells.

Growth hormone (GH) deficiency is characterized by impaired growth and development, and is currently treated by repeated administration of recombinant human GH (hGH). Encapsulated cell therapy (ECT) may offer a less demanding treatment-strategy for long-term production and release of GH into circulation. We used PiggyBac-based (PB) transposon delivery for engineering retinal pigment epithelial cells (ARPE-19), and tested a series of viral and non-viral promoters as well as codon-optimization to enhance transgene expression. Engineered cells were loaded into TheraCyte macrocapsules and secretion was followed in vitro and in vivo. The cytomegalovirus (CMV) promoter supports strong and persistent transgene expression, and we achieved clonal cell lines secreting over 6 µg hGH/106 cells/day. Codon-optimization of the hGH gene did not improve secretion. ARPE-19 cells endured encapsulation in TheraCyte devices, and resulted in steady hormone release for at least 60 days in vitro. A short-term pilot experiment in immunodeficient SCID mice demonstrated low systemic levels of hGH from a single 40 µL capsule implanted subcutaneously. No significant increase in weight increase or systemic hGH was detected after 23 days in the GH-deficient lit/SCID mouse model using 4.5 µL capsules loaded with the highest secreting clone of ARPE-19 cells. Our results demonstrate that PB-mediated engineering of ARPE-19 is an efficient way to generate hormone secreting cell lines compatible with macroencapsulation, and our CMV-driven expression cassette allows for identification of clones with high level and long-term secretory activity without addition of insulator elements. Our results pave the way for further in vivo studies of encapsulated cell therapy.

Efficacy and safety of growth hormone therapy in children with Noonan syndrome.

Patients with Noonan syndrome typically have a target height <2 standard deviations compared to the general population, and half of the affected adults remain permanently below the 3rd centile for height, though their short stature might result from a multifactorial etiology, not-yet fully understood. The secretion of growth hormone (GH) following the classic GH stimulation tests is often normal, with baseline insulin-like growth factor-1 (IGF-1) levels at the lower normal limits, but patients with Noonan syndrome have also a possible moderate response to GH therapy, leading to a final increased height and substantial improvement in growth rate. Aim of this review was to evaluate both safety and efficacy of GH therapy in children and adolescents with Noonan syndrome, also evaluating as a secondary aim the possible correlations between the underlying genetic mutations and GH responses.

Short stature related to Growth Hormone Insensitivity (GHI) in childhood.

Linear growth during childhood is the result of the synergic contribution of different factors. The best growth determinant system during each period of life is represented by the growth hormone-insulin-like growth factor axis (GH-IGF), even if several other factors are involved in normal growth. Within the broad spectrum of growth disorders, an increased importance has been placed on growth hormone insensitivity (GHI). GHI was reported for the first time by Laron as a syndrome characterized by short stature due to GH receptor (GHR) mutation. To date, it is recognized that GHI represents a wide diagnostic category, including a broad spectrum of defects. The peculiar characteristic of GHI is the low IGF-1 levels associated with normal or elevated GH levels and the lack of IGF-1 response after GH administration. Recombinant IGF-1 preparations may be used in the treatment of these patients.

Amino acid substitutions in human growth hormone affect secondary structure and receptor binding.

The interaction between human Growth Hormone (hGH) and hGH Receptor (hGHR) has basic relevance to cancer and growth disorders, and hGH is the scaffold for Pegvisomant, an anti-acromegaly therapeutic. For the latter reason, hGH has been extensively engineered by early workers to improve binding and other properties. We are particularly interested in E174 which belongs to the hGH zinc-binding triad; the substitution E174A is known to significantly increase binding, but to now no explanation has been offered. We generated this and several computationally-selected single-residue substitutions at the hGHR-binding site of hGH. We find that, while many successfully slow down dissociation of the hGH-hGHR complex once bound, they also slow down the association of hGH to hGHR. The E174A substitution induces a change in the Circular Dichroism spectrum that suggests the appearance of coiled-coiling. Here we show that E174A increases affinity of hGH against hGHR because the off-rate is slowed down more than the on-rate. For E174Y (and certain mutations at other sites) the slowdown in on-rate was greater than that of the off-rate, leading to decreased affinity. The results point to a link between structure, zinc binding, and hGHR-binding affinity in hGH.

A GHRHR founder mutation causes isolated growth hormone deficiency type IV in a consanguineous Pakistani family.

Background: Isolated 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. Objectives: To 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. Methods: Clinical 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. Results: All 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. Conclusion: These 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.

Gene Content and Coding Diversity of the Growth Hormone Loci of Apes.

The growth hormone (GH) locus has experienced a dramatic evolution in primates, becoming multigenic and diverse in anthropoids. Despite sequence information from a vast number of primate species, it has remained unclear how the multigene family was favored. We compared the structure and composition of apes' GH loci as a prerequisite to understanding their origin and possible evolutionary role. These thorough analyses of the GH loci of the chimpanzee, gorilla, and orangutan were done by resorting to previously sequenced bacterial artificial chromosomes (BACs) harboring them, as well as to their respective genome projects data available in GenBank. The GH loci of modern man, Neanderthal, gibbon, and wild boar were retrieved from GenBank. Coding regions, regulatory elements, and repetitive sequences were identified and compared among species. The GH loci of all the analyzed species are flanked by the genes CD79B (5') and ICAM-1 (3'). In man, Neanderthal, and chimpanzee, the loci were integrated by five almost indistinguishable genes; however, in the former two, they rendered three different hormones, and in the latter, four different proteins were derived. Gorilla exhibited six genes, gibbon seven, and orangutan four. The sequences of the proximal promoters, enhancers, P-elements, and a locus control region (LCR) were highly conserved. The locus evolution might have implicated duplications of the ancestral pituitary gene (GH-N) and subsequent diversification of the copies, leading to the placental single GH-V gene and the multiple CSH genes.

Stratification of a Phelan-McDermid Syndrome Population Based on Their Response to Human Growth Hormone and Insulin-like Growth Factor.

Phelan-McDermid syndrome (PMS), caused by pathogenic variants in the SHANK3 gene or 22q13 deletions, is characterized by intellectual disability, autistic features, developmental delays, and neonatal hypotonia. Insulin-like growth factor 1 (IGF-1) and human growth hormone (hGH) have been shown to reverse neurobehavioral deficits in PMS. We assessed the metabolic profiling of 48 individuals with PMS and 50 controls and determined subpopulations by taking the top and bottom 25% of responders to hGH and IGF-1. A distinct metabolic profile for individuals with PMS showed a reduced ability to metabolize major energy sources and a higher metabolism of alternative energy sources. The analysis of the metabolic response to hGH or IGF-1 highlighted a major overlap between both high and low responders, validating the model and suggesting that the two growth factors share many target pathways. When we investigated the effect of hGH and IGF-1 on the metabolism of glucose, the correlation between the high-responder subgroups showed less similarity, whereas the low-responders were still relatively similar. Classification of individuals with PMS into subgroups based on responses to a compound can allow an investigation into pathogenic mechanisms, the identification of molecular biomarkers, an exploration of in vitro responses to candidate drugs, and eventually the selection of better candidates for clinical trials.

CTCF variant begets to short stature by down-regulation of IGF1.

Pathogenic variants in the transcription factor CCCTC-binding factor (CTCF) are associated with mental retardation, autosomal dominant 21 (MRD21, MIM#615502). Current studies supported the strong relationship between CTCF variants and growth, yet the mechanism of CTCF mutation leading to short stature is not known. Clinical information, treatment regimens, and follow-up outcomes of a patient with MRD21 were collected. The possible pathogenic mechanisms of CTCF variants leading to short stature were investigated using immortalized lymphocyte cell lines (LCLs), HEK-293T, and immortalized normal human liver cell lines (LO2). This patient received long-term treatment with recombinant human growth hormone (rhGH) which resulted in an increased height of 1.0 SDS. She had low serum insulin-like growth factor 1 (IGF1) before the treatment and the IGF1 level was not significantly increased during the treatment (-1.38 ± 0.61 SDS). The finding suggested that the CTCF R567W variant could have impaired IGF1 production pathway. We further demonstrated that the mutant CTCF had a reduced ability to bind to the promoter region of IGF1, consequently significantly reducing the transcriptional activation and expression of IGF1. Our novel results demonstrated a direct positive regulation of CTCF on the transcription of the IGF1 promoter. The impaired IGF1 expression due to CTCF mutation may explain the substandard effect of rhGH treatment on MRD21 patients. This study provided novel insights into the molecular basis of CTCF-associated disorder.