Dento-maxillofacial abnormalities are highly prevalent and arise as a result of a variety of etiological factors, presenting substantial challenges to treatment. The JAK-STAT signaling plays a pivotal role in dentofacial development, regulating endochondral ossification, intramembranous ossification, dental follicle formation, and enamel development. Mutations in the JAK-STAT signaling lead to syndromes associated with severe dento-maxillofacial abnormalities, including Growth Hormone Insensitivity Syndrome and Autosomal Dominant Hyper-IgE Syndrome. Corresponding mouse disease models have been developed to simulate the phenotypes observed in clinical patients and investigate their underlying mechanism. Meanwhile, several medications targeting JAK-STAT signaling, including baricitinib and imatinib, have been developed for clinical application, demonstrating significant effects in skeletal disorders such as osteoporosis and osteoarthritis, indicating promising effects in development and abnormalities of dento-maxillofacial. In this review, we aim to summarize the role of JAK-STAT signaling in the development and abnormalities of dento-maxillofacial bone, and the relevant molecules that may be utilized for clinical treatment, to shed new light on the precise treatment of dento-maxillofacial abnormalities.

Laron syndrome (LS) is a rare autosomal recessive disorder caused by mutations in the growth hormone (GH) receptor gene, resulting in GH resistance and reduced levels of insulin-like growth factor 1 (IGF-1). Patients with LS exhibit severe growth retardation, low IGF-1 levels, elevated basal GH, and poor response to GH stimulation. Recombinant IGF-1 is the only approved treatment and has been shown to improve linear growth. This study evaluates the long-term efficacy and safety of IGF-1 therapy in a large cohort of LS patients treated at King Faisal Specialist Hospital and Research Center (KFSH &amp; RC), Riyadh, Saudi Arabia over 22 years. We conducted a retrospective review of medical records for 28 patients with growth hormone insensitivity syndrome, including 12 males and 16 females, treated with IGF-1 from 1998 to 2020. Patients were selected based on criteria including age over 2 years, height standard deviation score (SDS) ≤-2.8, normal or elevated GH secretion (>2.5 ng/mL), IGF-1 levels <50 ng/mL, and insensitivity to exogenous GH. IGF-1 was administered initially at 40 μg/kg/dose subcutaneously twice daily, escalating to a maximum of 120 μg/kg/dose as tolerated. Dosage was adjusted to minimize hypoglycemia risk, with blood glucose monitored frequently during hospitalization. In addition, molecular genetic results were reviewed for each patient in the cohort. IGF-1 treatment significantly increased height velocity (HV) from a baseline of 3.4 cm/year to 6.5 cm/year in the first year (mean difference of 3.1 cm/year, p < 0.0001). In the second year, HV remained elevated at 5 cm/year (mean difference of 1.6 cm/year, p = 0.0015). Long-term follow-up over 10 years demonstrated sustained improvements in HV compared to baseline, with the most substantial gains occurring within the initial 5 years. Weight SDSs also showed significant improvement. Age at the start of therapy did not notably affect growth outcomes, though longer treatment durations were associated with greater growth. Ten disease-causing variants in the GHR gene were identified in 24 of the 28 LS patients. IGF-1 therapy significantly enhanced linear growth in children with Laron syndrome and was generally well tolerated. Although many patients did not reach normal adult height, the growth achieved with IGF-1 treatment was markedly better than expected without therapy. This study underscores the effectiveness of IGF-1 in improving growth outcomes and highlights the need for continued longitudinal studies to optimize treatment strategies and manage potential complications.

Growth hormone insensitivity syndrome (GHIS) is a rare genetic disorder characterized by short stature due to the body's inability to effectively utilize growth hormone (GH). This case report describes a patient with concurrent hypothyroidism and GHIS. This patient is an 11-year-old female presented with short stature; general examination suggested a prominent forehead and a depressed nasal bridge. Laboratory evaluations revealed elevated thyroid-stimulating hormone (TSH) levels alongside low levels of triiodothyronine (T3) and thyroxine (T4), indicating hypothyroidism. Additionally, elevated GH levels and significantly reduced insulin-like growth factor 1 (IGF-1) levels confirmed the diagnosis of GHIS. The patient was managed with thyroid hormone replacement therapy and recombinant GH. This dual therapeutic approach will lead to improvements in both thyroid function and growth parameters. This case underscores the importance of recognizing and addressing coexisting endocrine disorders in patients with GHIS to optimize their growth and developmental outcomes. Early diagnosis and a comprehensive treatment strategy are essential for managing such complex cases effectively.

Although the majority of growth hormone insensitivity syndrome (GHIS) cases are classical, the spectrum of clinical phenotypes has expanded to include "atypical" GHIS subjects with milder phenotypes due to very rare heterozygous growth hormone receptor (GHR) mutations with dominant negative effects. A 13-year-old pubertal boy presented with short stature (-1.7 SDS) and delayed bone age (11.5 years). His serum IGF-1 was low (16 ng/mL; reference range: 179-540). IGFBP-3 (1.3 mg/L; 3.1-9.5) and ALS (565 mU/mL; 1,500-3,500) were also low. GH stimulation test was normal, and GHBP was markedly elevated (6,300 pmol/L; 240-3,000). Additionally, the boy had insulin resistance and liver steatosis. His final height reached -1.8 SDS, which was 3.0 SDS below his mid-parental height. GHR gene from genomic DNA and established primary fibroblast culture was analyzed and a synonymous heterozygous GHR: c.945G&gt;A variant, in the last nucleotide of exon 9 (encoding intracellular domain of GHR) was identified. In vitro analysis of the GHR cDNA demonstrated a splicing defect, leading to the heterozygous excision of exon 9. The final predicted product was a truncated GHR protein which explained the elevated GHBP levels. We describe the first synonymous heterozygous GHR splicing variant in the exon 9-encoding part of the intracellular domain of GHR identified in a patient with mild short stature, thus supporting the continuum of genotype-phenotype of GHIS.

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.