Genetic analysis of the PAPP-A2 gene and evaluation of free IGF-1, IGFBP-5, and ALS concentrations in a group of 22 patients with idiopathic short stature.

INTRODUCTION: Short stature is one of the main reasons for consultation in outpatient clinics and paediatric endocrinology departments and is defined as height below the 3rd centile or less than -2 standard deviations (SDs). MATERIAL AND METHODS: The study's overarching aim was to analyse the PAPP-A2 gene at mutation sites described to date and at exons 3, 4, and 5, which encode the fragment of the catalytic domain with the active site of the pregnancy-associated plasma protein A2 (PAPP-A2) protein. The secondary aims of the study were clinical and auxological analysis of a group of patients with idiopathic short stature and biochemical analysis of growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis parameters not assessed as part of the routine diagnosis of short stature, such as free IGF-1, insulin-like growth factor binding protein 5 (IGFBP-5), and acid-labile subunit (ALS) levels. Molecular analysis of the PAPP-A2 gene was performed using polymerase chain reaction (PCR) and direct sequencing. Biochemical analysis of free IGF-1, IGFBP-5, and ALS was performed by enzyme-linked immunosorbent assay (ELISA). RESULTS: The mean height standard deviation score (HSDS) in the study group was -2.95. None of the patients exhibited previously described mutations in the PAPP-A2 gene or mutations in exons 3, 4, and 5 encoding the fragment of catalytic domain with the active site of the PAPP-A2 protein. In 4 patients, the known, non-pathogenic, heterozygotic polymorphism c.2328C>T(rs10913241) in exon 5 was found. CONCLUSIONS: Free IGF-1 levels correlate better with height and HSDS than total IGF-1 levels. The previously described mutations in the PAPP-A2 gene and mutations in exons 3, 4, and 5 encoding the fragment of catalytic domain with the active site of the PAPP-A2 protein were not detected; only the known and non-pathogenic, heterozygotic polymorphism c.2328C>T(rs10913241) in exon 5 of the PAPP-A2 gene was observed.

Profound T Lymphocyte and DNA Repair Defect Characterizes Schimke Immuno-Osseous Dysplasia.

Schimke immuno-osseous dysplasia is a rare multisystemic disorder caused by biallelic loss of function of the SMARCAL1 gene that plays a pivotal role in replication fork stabilization and thus DNA repair. Individuals affected from this disease suffer from disproportionate growth failure, steroid resistant nephrotic syndrome leading to renal failure and primary immunodeficiency mediated by T cell lymphopenia. With infectious complications being the leading cause of death in this disease, researching the nature of the immunodeficiency is crucial, particularly as the state is exacerbated by loss of antibodies due to nephrotic syndrome or immunosuppressive treatment. Building on previous findings that identified the loss of IL-7 receptor expression as a possible cause of the immunodeficiency and increased sensitivity to radiation-induced damage, we have employed spectral cytometry and multiplex RNA-sequencing to assess the phenotype and function of T cells ex-vivo and to study changes induced by in-vitro UV irradiation and reaction of cells to the presence of IL-7. Our findings highlight the mature phenotype of T cells with proinflammatory Th1 skew and signs of exhaustion and lack of response to IL-7. UV light irradiation caused a severe increase in the apoptosis of T cells, however the expression of the genes related to immune response and regulation remained surprisingly similar to healthy cells. Due to the disease's rarity, more studies will be necessary for complete understanding of this unique immunodeficiency.

SMAD4 mutations causing Myhre syndrome are under positive selection in the male germline.

While it is widely thought that de novo mutations (DNMs) occur randomly, we previously showed that some DNMs are enriched because they are positively selected in the testes of aging men. These "selfish" mutations cause disorders with a shared presentation of features, including exclusive paternal origin, significant increase of the father's age, and high apparent germline mutation rate. To date, all known selfish mutations cluster within the components of the RTK-RAS-MAPK signaling pathway, a critical modulator of testicular homeostasis. Here, we demonstrate the selfish nature of the SMAD4 DNMs causing Myhre syndrome (MYHRS). By analyzing 16 informative trios, we show that MYHRS-causing DNMs originated on the paternally derived allele in all cases. We document a statistically significant epidemiological paternal age effect of 6.3 years excess for fathers of MYHRS probands. We developed an ultra-sensitive assay to quantify spontaneous MYHRS-causing SMAD4 variants in sperm and show that pathogenic variants at codon 500 are found at elevated level in sperm of most men and exhibit a strong positive correlation with donor's age, indicative of a high apparent germline mutation rate. Finally, we performed in vitro assays to validate the peculiar functional behavior of the clonally selected DNMs and explored the basis of the pathophysiology of the different SMAD4 sperm-enriched variants. Taken together, these data provide compelling evidence that SMAD4, a gene operating outside the canonical RAS-MAPK signaling pathway, is associated with selfish spermatogonial selection and raises the possibility that other genes/pathways are under positive selection in the aging human testis.

Establishment of a human induced pluripotent stem cell line (SDQLCHi079-A) from a patient with Johanson-Blizzard syndrome carrying heterozygous mutation in UBR1 gene.

Johanson-Blizzard syndrome (JBS) is an autosomal recessive disorder. We established an induced pluripotent stem cell (iPSC) line from peripheral blood mononuclear cells of a 2-year-old boy with Johanson-Blizzard syndrome carrying a compound heterozygous mutation of c.3167C>G (p.S1056X) and c.1911 + 14C>G(splicing) in the UBR1 gene. This iPSC line was free of exogenous gene, expressed stemness markers, exhibited differentiation potential, had normal karyotype and harbored the same mutations found in the patient. The iPSC cellline can serve as a disease model in drug development and novel personalized therapies.

Delineation of the phenotypes and genotypes of PIK3CA-related overgrowth spectrum in East asians.

PIK3CA-related overgrowth spectrum (PROS) is an umbrella term to describe a diverse range of developmental disorders. Research to date has predominantly emerged from Europe and North America, resulting in a notable scarcity of studies focusing on East Asian populations. Currently, the prevalence and distribution of PIK3CA variants across various genetic loci and their correlation with distinct phenotypes in East Asian populations remain unclear. This study aims to elucidate the phenotype-genotype correlations of PROS in East Asian populations. We presented the phenotypes and genotypes of 82 Chinese patients. Among our cohort, 67 individuals carried PIK3CA variants, including missense, frameshift, and splice variants. Six patients presented with both PIK3CA and an additional variant. Seven PIK3CA-negative patients exhibited overlapping PROS manifestations with variants in GNAQ, AKT1, PTEN, MAP3K3, GNA11, or KRAS. An integrative review of the literature pertaining to East Asian populations revealed that specific variants are uniquely associated with certain PROS phenotypes. Some rare variants were exclusively identified in cases of megalencephaly and diffuse capillary malformation with overgrowth. Non-hotspot variants with undefined oncogenicity were more common in CNS phenotypes. Diseases with vascular malformation were more likely to have variants in the helical domain, whereas phenotypes involving adipose/muscle overgrowth without vascular abnormalities predominantly presented variants in the C2 domain. Our findings underscore the unique phenotype-genotype patterns within the East Asian PROS population, highlighting the necessity for an expanded cohort to further elucidate these correlations. Such endeavors would significantly facilitate the development of PI3Kα selective inhibitors tailored for the East Asian population in the future.

Myhre syndrome in adulthood: clinical variability and emerging genotype-phenotype correlations.

Myhre syndrome (MS, MIM 139210) is a rare multisystemic disorder caused by recurrent pathogenic missense variants in SMAD4. The clinical features have been mainly documented in childhood and comprise variable neurocognitive development, recognizable craniofacial features, a short stature with a pseudo-muscular build, hearing loss, thickened skin, joint limitations, diverse cardiovascular and airway manifestations, and increased fibrosis often following trauma or surgery. In contrast, adults with MS are underreported obscuring potential clinical variability. Here, we describe 24 adults with MS, including 17 diagnosed after the age of 18 years old, and we review the literature on adults with MS. Overall, our cohort shows a milder phenotype as well as lower mortality rates compared to what has been published in literature. Individuals with a codon 500 variant in SMAD4 present with a more pronounced neurodevelopmental and systemic phenotype. However, in contrast to the literature, we observe cardiovascular abnormalities in individuals with the p.(Arg496Cys) variant. In addition, we describe scoliosis as a new manifestation and we report fertility in two additional males with the p.(Arg496Cys). In conclusion, our study contributes novel insights into the clinical variability of MS and underscores the importance of variant-specific considerations, and we provide recommendations for the management of MS in adulthood.

Clinical and genetic analysis of a case of O'Donnell-Luria-Rodan syndrome manifesting as growth retardation. / 以生长发育迟缓为表现的1例O'Donnell-Luria-Rodanç»¼åˆå¾ä¸´åºŠä¸Žé—ä¼ å­¦ç‰¹å¾åˆ†æž.

O'Donnell-Luria-Rodan (ODLURO) syndrome is an autosomal dominant genetic disorder caused by mutations in the KMT2E (lysine methyltransferase 2E) gene. The Third Xiangya Hospital of Central South University admitted a 12-year and 9-month-old male patient who presented with growth retardation, intellectual disability, and distinctive facial features. Peripheral blood was collected from the patient, and DNA was extracted for genetic testing. Chromosome karyotyping showed 46XY. Whole-exome sequencing and low-coverage massively parallel copy number variation sequencing (CNV-seq) revealed a 506 kb heterozygous deletion in the 7q22.3 region, which includes 6 genes, including KMT2E. The patient was diagnosed with ODLURO syndrome. Both the patient's parents and younger brother had normal clinical phenotypes and genetic test results, indicating that this deletion was a de novo mutation. The clinical and genetic characteristics of this case can help increase clinicians' awareness of ODLURO syndrome.

Expanding the genetic and clinical spectrum of Tatton-Brown-Rahman syndrome in a series of 24 French patients.

BACKGROUND: Tatton-Brown-Rahman syndrome (TBRS; OMIM 615879), also known as DNA methyltransferase 3 alpha (DNMT3A)-overgrowth syndrome (DOS), was first described by Tatton-Brown in 2014. This syndrome is characterised by overgrowth, intellectual disability and distinctive facial features and is the consequence of germline loss-of-function variants in DNMT3A, which encodes a DNA methyltransferase involved in epigenetic regulation. Somatic variants of DNMT3A are frequently observed in haematological malignancies, including acute myeloid leukaemia (AML). To date, 100 individuals with TBRS with de novo germline variants have been described. We aimed to further characterise this disorder clinically and at the molecular level in a nationwide series of 24 French patients and to investigate the correlation between the severity of intellectual disability and the type of variant. METHODS: We collected genetic and medical information from 24 individuals with TBRS using a questionnaire released through the French National AnDDI-Rares Network. RESULTS: Here, we describe the first nationwide French cohort of 24 individuals with germline likely pathogenic/pathogenic variants in DNMT3A, including 17 novel variants. We confirmed that the main phenotypic features were intellectual disability (100% of individuals), distinctive facial features (96%) and overgrowth (87%). We highlighted novel clinical features, such as hypertrichosis, and further described the neurological features and EEG results. CONCLUSION: This study of a nationwide cohort of individuals with TBRS confirms previously published data and provides additional information and clarifies clinical features to facilitate diagnosis and improve care. This study adds value to the growing body of knowledge on TBRS and broadens its clinical and molecular spectrum.

Deletion of Trps1 regulatory elements recapitulates postnatal hip joint abnormalities and growth retardation of Trichorhinophalangeal syndrome in mice.

Trichorhinophalangeal syndrome (TRPS) is a genetic disorder caused by point mutations or deletions in the gene-encoding transcription factor TRPS1. TRPS patients display a range of skeletal dysplasias, including reduced jaw size, short stature, and a cone-shaped digit epiphysis. Certain TRPS patients experience early onset coxarthrosis that leads to a devastating drop in their daily activities. The etiologies of congenital skeletal abnormalities of TRPS were revealed through the analysis of Trps1 mutant mouse strains. However, early postnatal lethality in Trps1 knockout mice has hampered the study of postnatal TRPS pathology. Here, through epigenomic analysis we identified two previously uncharacterized candidate gene regulatory regions in the first intron of Trps1. We deleted these regions, either individually or simultaneously, and examined their effects on skeletal morphogenesis. Animals that were deleted individually for either region displayed only modest phenotypes. In contrast, the Trps1Δint/Δint mouse strain with simultaneous deletion of both genomic regions exhibit postnatal growth retardation. This strain displayed delayed secondary ossification center formation in the long bones and misshaped hip joint development that resulted in acetabular dysplasia. Reducing one allele of the Trps1 gene in Trps1Δint mice resulted in medial patellar dislocation that has been observed in some patients with TRPS. Our novel Trps1 hypomorphic strain recapitulates many postnatal pathologies observed in human TRPS patients, thus positioning this strain as a useful animal model to study postnatal TRPS pathogenesis. Our observations also suggest that Trps1 gene expression is regulated through several regulatory elements, thus guaranteeing robust expression maintenance in skeletal cells.

Functional studies in yeast confirm the pathogenicity of a new GINS3 Meier-Gorlin syndrome variant.

Meier-Gorlin syndrome (MGORS) is an autosomal recessive disorder characterized by short stature, microtia, and patellar hypoplasia, and is caused by pathogenic variants of cellular factors involved in the initiation of DNA replication. We previously reported that biallelic variants in GINS3 leading to amino acid changes at position 24 (p.Asp24) cause MGORS. Here, we describe the phenotype of a new individual homozygous for the Asp24Asn variant. We also report the clinical characteristics of an individual harboring a novel homozygous GINS3 variant (Ile25Phe) and features suggestive of MGORS. Modification of the corresponding residue in yeast Psf3 (Val9Phe) compromised S phase progression compared to a humanized Psf3 Val9Ile variant. Expression of Psf3 Val9Phe in yeast also caused sensitivity to elevated temperature and the replicative stress-inducing drug hydroxyurea, confirming partial loss of function of this variant in vivo and allowing us to upgrade the classification of this variant. Taken together, these data validate the critical importance of the GINS DNA replication complex in the molecular etiology of MGORS.

[Growth Hormone treatment in children with Growth Hormone deficiency, idiopathic short stature, SHOX gene mutation, small for gestational age and Turner syndrome]. / Tratamiento con Hormona de Crecimiento en pacientes con déficit de hormona de crecimiento, talla baja idiopática, mutación gen SHOX, pequeños para edad gestacional y síndrome de Turner.

Growth hormone (GH) is effective in improving height in several conditions. OBJECTIVE: To describe the evolution of a group of children who received GH in a tertiary center between 2012-2022. PATIENTS AND METHOD: Descriptive, retrospective study. We analyzed the impact on height after GH use with Z-score according to etiology, age at onset and bone age. Patients under 15 years old at baseline and receiving GH for at least 12 months, with diagnoses of GH deficiency (GHD), idiopathic short stature (ISS), small for gestational age (SGA), SHOX Haploinsufficiency (SHOX) and Turner syndrome (TS) were included. Height was expressed as Z-score for age and sex, according to NCHS curves. RESULTS: 145 children received GH. Sixty patients were excluded due to irregular administration, incomplete data, less than 12 months of GH, change of hospital, and associated comorbidities. Seventy-three patients were analyzed, 23 GHD, 15 ISS, 20 SGA, 9 SHOX and 6 TS patients. Significant improvement in height (Z-score for age and sex) was observed in SGA (1.4 ± 0.8 gain; p < 0.001), GHD (1.1 ± 1.0; p < 0.001), ISS (1.1 ± 0.8; p < 0.001) and SHOX (0.8 ± 0.7; p = 0.007) patients. In TS, a non-statistically significant improvement was observed (0.7 ± 0.8; p = 0.085). In GHD, onset before 3 years showed a gain of 1.9 ± 1.1, vs 0.7 ± 0.6 (p = 0.083) and in ISS onset with bone age less than 9 years increased it by 1.7 ± 0.5 vs 0.5 ± 0.5 (p < 0.001). ADVERSE EVENTS: 27/73 (37%) headache, 18/73 (24%) lower extremity pain, 1/73 (1.5%) dizziness, 1/73 (1.5%) scoliosis, 1/73 (1.5%) epiphysiolysis and 1/73 (1.5%) craniopharyngioma recurrence. CONCLUSIONS: Children with GHD, ISS, SHOX mutation and SGA significantly improved their height, highlighting in GHD and ISS the importance of early treatment. Treatment was well tolerated in the 5 groups analyzed.

GAPO syndrome: a novel variant in ANTXR1 gene.

BACKGROUND: GAPO syndrome is a rare autosomal recessive disorder characterized by the acronym of growth retardation, alopecia, pseudo-anodontia and progressive optic atrophy. While the genetic alteration of the ANTXR1 gene has been known for its cause, the full range of its clinical and genetic manifestations is not well explored due to the syndrome's extreme rarity. MATERIALS/METHODS: We report two children born to a non-consanguineous parent in India with classical features of GAPO syndrome. The whole exome sequencing analysis (WES) was performed in both siblings, and the parent's genetic and clinical status was determined. The identified variation was characterized in silico using homology-based protein modelling. RESULTS: In WES analysis, a homozygous ANTXR1 gene indel variant c. 151_152 + 2delAAGT (p.Lys51fs) was identified in both siblings. The parents were identified as the carriers of the ANTXR1 variant. Additionally, they also displayed mild GAPO-related facial and glaucomatous features. In silico analysis and homology-based ANTXR1 protein structure illustrate a frameshift and the subsequent premature truncation of the protein. CONCLUSIONS: Our reports contribute to the comprehension of GAPO syndrome within the Indian context describing an ANTXR1 novel variant causing premature protein truncation. WES-based genetic testing can significantly aid in expertly diagnosing GAPO syndrome. In the present case scenario, a variable penetrance of ANTXR1 variation was acknowledged as the carrier parents also had a mild degree of GAPO-related features. Future reports that include parental clinical diagnosis can offer further insights in this context.

Clinical characteristics of and growth hormone treatment effects on short stature with type 1 insulin-like growth factor receptor (IGF1R) gene alteration.

Short stature with IGF-1 receptor (IGF1R) gene alteration is known as small-for-gestational-age (SGA) short stature with elevated serum IGF1 levels. Its prevalence and clinical characteristics remain unclear. No adapted treatment is available for short stature related to IGF1R gene alteration in Japan, and genetic testing is not yet widely accessible. We investigated short stature with IGF1R gene alterations and analyzed the clinical data of 13 patients using the results of questionnaires issued to the Japanese Society for Pediatric Endocrinology. Four cases were caused by a deletion of chromosome 15q26.3, and eight were caused by heterozygous pathogenic variants in the IGF1R gene. Cases with deletions showed a more severe degree of growth impairment (-4.5 ± 0.43 SD) than those caused by pathological variants (-2.71 ± 0.15 SD) and were accompanied by neurodevelopmental delay. However, cases caused by pathological variants lacked distinctive features. Only three of the 12 cases demonstrated serum IGF1 values exceeding +2 SD, and the other three had values below 0 SD. Four patients did not meet the criteria for SGA at birth. Six patients received GH therapy for SGA short stature and showed improvement in growth rate without any side effects or elevated serum IGF1 levels during treatment. Elevated IGF1 levels (over +2 SD) after GH treatment should be considered a suspicious finding. Owing to the lack of distinctive features, there was a possibility of undiagnosed cases of this condition. Promoting genetic testing and clinical trials on GH administration for this condition is recommended.

Children With Idiopathic Short Stature: An Expanding Role for Genetic Investigation in Their Medical Evaluation.

Short stature in children is a common reason for referral to a pediatric endocrinologist. Many genetic, nutritional, psychological, illness-related, and hormonal causes must be excluded before labeling as idiopathic. Idiopathic short stature is not a diagnosis, but rather describes a large, heterogeneous group of children, who are short and often slowly growing. As new testing paradigms become available, the pool of patients labeled as idiopathic will shrink, although most will have a polygenic cause. Given that many of the new diagnoses are involved in growth plate biology, physical examination should assess for subtle dysmorphology or disproportion of the skeleton that may indicate a heterozygous mutation that in its homozygous state would be apparent. When laboratory evaluations are negative, one may consider genetic testing, such as targeted gene or gene panel, comparative genomic hybridization, or whole exome or whole genome sequencing (respectively). With a known genetic diagnosis, targeted therapy may be possible rather than recombinant human growth hormone, where response is generally poorer than that for children with growth hormone deficiency, because the variety of diagnoses may have varying growth hormone sensitivity. A firm diagnosis has heuristic value: to truncate further diagnostic evaluation, alert the clinician to other possible comorbidities, inform the family for genetic counseling, and direct appropriate targeted therapy, if available.

Investigating Novel Therapeutic Approaches for Idiopathic Short Stature: Targeting siRNA and Growth Hormone Delivery to the Growth Plate Using Exosome Nanoparticles.

Idiopathic short stature (ISS) is a common childhood condition with largely unknown underlying causes. Recent research highlights the role of circulating exosomes in the pathogenesis of various disorders, but their connection to ISS remains unexplored. In the experiments, human chondrocytes are cocultured with plasma exosomes from ISS patients, leading to impaired chondrocyte growth and bone formation. Elevated levels of a specific long non-coding RNA (lncRNA), ISSRL, are identified as a distinguishing factor in ISS, boasting high specificity and sensitivity. Silencing ISSRL in ISS plasma exosomes reverses the inhibition of chondrocyte proliferation and bone formation. Conversely, overexpression of ISSRL in chondrocytes impedes their growth and bone formation, revealing its mechanism of action through the miR-877-3p/GZMB axis. Subsequently, exosomes (CT-Exo-siISSRL-oeGH) with precise cartilage-targeting abilities are engineered, loaded with customized siRNA for ISSRL and growth hormone. This innovative approach offers a therapeutic strategy to address ISS by rectifying abnormal non-coding RNA expression in growth plate cartilage and delivering growth hormone with precision to promote bone growth. This research provides valuable insights into ISS diagnosis and treatment, highlighting the potential of engineered exosomes.

A further case of chondrodysplasia with growth failure occurring after hematopoietic stem cell transplantation (HSCT).

There is an emerging body of evidence showing that young patients, post haematopoietic stem cell transplantation (HSCT), can develop skeletal changes that mimic an osteochondrodysplasia process. The key discriminator is that these children have had otherwise normal growth and skeletal development before the therapeutic intervention (HSCT), typically for a haematological malignancy. Herein we present that case of a boy who underwent HSCT for Haemophagocytic Lymphohistiocytosis (HLH) aged 2 years. Following Intervention with HSCT this boy's growth has severely decelerated (stature less than 1st centile matched for age) and he has developed a spondyloepiphyseal dysplasia.

Estrogen Receptor 1 Gene Polymorphism and its Association with Idiopathic Short Stature in a North Indian Population

Objective: In the hypothalamic-pituitary-gonadotrophin axis, estrogen plays a key role in the regulation of bone maturation and growth plate closure. This study was designed to explore the link between single nucleotide polymorphisms (SNPs) in the estrogen receptor 1 (ESR1) gene with idiopathic short stature (ISS) susceptibility in a North Indian population. Methods: Four SNPs of ESR1 (rs543650, rs6557177, rs2234693 and rs9340799) were genotyped by Sanger sequencing in ISS patients and controls. Linkage disequilibrium (LD) and haplotyping were done by SNPStat and SHEsisPlus software. The extent of LD was determined by calculating D' and R2 values in SNP paired combinations. Results: Fifty-two ISS patients were compared with 68 controls. A significant positive association was found between rs6557177 and rs543650 genotype and ISS susceptibility. The frequencies of the rs6557177 CC genotype [p=0.030; odds ratio (OR)=0.13; 95% confidence interval (CI): 0.01-1.10] and rs543650 genotype TT (p=0.043; OR=0.29; 95% CI: 0.09-0.92) were increased in the ISS group compared with controls. However, no significant correlation was observed between clinical parameters of patients and these SNPs. rs543650 showed strong LD with rs2234693 and rs9340799, similarly rs2234693 and rs9340799. Conclusion: Our study showed that the CC genotype at rs6557177 and TT genotype at rs543650 of ESR1 constituted a risk factor for developing ISS in North Indian children. These findings may lead to a better understanding of the SNPs associated with ISS susceptibility.

Characterization of HMGA2 variants expands the spectrum of Silver-Russell syndrome.

Silver-Russell syndrome (SRS) is a heterogeneous disorder characterized by intrauterine and postnatal growth retardation. HMGA2 variants are a rare cause of SRS and its functional role in human linear growth is unclear. Patients with suspected SRS negative for 11p15LOM/mUPD7 underwent whole-exome and/or targeted-genome sequencing. Mutant HMGA2 protein expression and nuclear localization were assessed. Two Hmga2-knockin mouse models were generated. Five clinical SRS patients harbored HMGA2 variants with differing functional impacts: 2 stop-gain nonsense variants (c.49G>T, c.52C>T), c.166A>G missense variant, and 2 frameshift variants (c.144delC, c.145delA) leading to an identical, extended-length protein. Phenotypic features were highly variable. Nuclear localization was reduced/absent for all variants except c.166A>G. Homozygous knockin mice recapitulating the c.166A>G variant (Hmga2K56E) exhibited a growth-restricted phenotype. An Hmga2Ter76-knockin mouse model lacked detectable full-length Hmga2 protein, similarly to patient 3 and 5 variants. These mice were infertile, with a pygmy phenotype. We report a heterogeneous group of individuals with SRS harboring variants in HMGA2 and describe the first Hmga2 missense knockin mouse model (Hmga2K56E) to our knowledge causing a growth-restricted phenotype. In patients with clinical features of SRS but negative genetic screening, HMGA2 should be included in next-generation sequencing testing approaches.