Clinical and Genetic Insights into Desbuquois Dysplasia: Review of 111 Case Reports.

Skeletal disorders encompass a wide array of conditions, many of which are associated with short stature. Among these, Desbuquois dysplasia is a rare but severe condition characterized by profound dwarfism, distinct facial features, joint hypermobility with multiple dislocations, and unique vertebral and metaphyseal anomalies. Desbuquois dysplasia is inherited in an autosomal recessive manner, with both the DBQD1 (MIM 251450) and DBQD2 (MIM 615777) forms resulting from biallelic mutations. Specifically, DBQD1 is associated with homozygous or compound heterozygous mutations in the CANT1 gene, while DBQD2 can result from mutations in either the CANT1 or XYLT1 genes. This review synthesizes the findings of 111 published case reports, including 54 cases of DBQD1, 39 cases of DBQD2, and 14 cases of the Kim variant (DDKV). Patients in this cohort had a median birth weight of 2505 g, a median length of 40 cm, and a median occipitofrontal circumference of 33 cm. The review highlights the phenotypic variations across Desbuquois dysplasia subtypes, particularly in facial characteristics, joint dislocations, and bone deformities. Genetic analyses revealed a considerable diversity in mutations, with over 35% of cases involving missense mutations, primarily affecting the CANT1 gene. Additionally, approximately 60% of patients had a history of parental consanguinity, indicating a potential genetic predisposition in certain populations. The identified mutations included deletions, insertions, and nucleotide substitutions, many of which resulted in premature stop codons and the production of truncated, likely nonfunctional proteins. These findings underscore the genetic and clinical complexity of Desbuquois dysplasia, highlighting the importance of early diagnosis and the potential for personalized therapeutic approaches. Continued research is essential to uncover the underlying mechanisms of this disorder and improve outcomes for affected individuals through targeted treatments.

Cant1 Affects Cartilage Proteoglycan Properties: Aggrecan and Decorin Characterization in a Mouse Model of Desbuquois Dysplasia Type 1.

Desbuquois dysplasia type 1 (DBQD1) is a recessive chondrodysplasia caused by mutations in the CANT1 gene, encoding for the Golgi Calcium-Activated Nucleotidase 1 (CANT1). The enzyme hydrolyzes UDP, the by-product of glycosyltransferase reactions, but it might play other roles in different cell types. Using a Cant1 knock-out mouse, we demonstrated that CANT1 is crucial for glycosaminoglycan (GAG) synthesis; however, its impact on the biochemical properties of cartilage proteoglycans remains unknown. Thus, in this work, we characterized decorin and aggrecan from primary chondrocyte cultures and cartilage biopsies of mutant mice at post-natal day 4 by Western blots and further investigated their distribution in the cartilage extracellular matrix (ECM) by immunohistochemistry. We demonstrated that the GAG synthesis defect caused by CANT1 impairment led to the synthesis and secretion of proteoglycans with shorter GAG chains compared with wild-type animals. However, this alteration did not result in the synthesis and secretion of decorin and aggrecan in the unglycanated form. Interestingly, the defect was not cartilage-specific since also skin decorin showed a reduced hydrodynamic size. Finally, immunohistochemical studies in epiphyseal sections of mutant mice demonstrated that the proteoglycan structural defect moderately affected decorin distribution in the ECM.

A long way to syndromic short stature.

BACKGROUND: Silver-Russell Syndrome (SRS, MIM #180860) is a clinically and genetically heterogeneous disorder characterized by intrauterine and postnatal growth retardation; SRS is also accompanied by dysmorphic features such as triangular facial appearance, broad forehead, body asymmetry and significant feeding difficulties. The incidence is unknown but estimated at 1:30,000-100,000 live births. The diagnosis of SRS is guided by specific criteria described in the Netchine-Harbison clinical scoring system (NH-CSS). CASE PRESENTATION: Hereby we describe four patients with syndromic short stature in whom, despite fitting the criteria for SRS genetic analysis (and one on them even meeting the clinical criteria for SRS), molecular analysis actually diagnosed a different syndrome. Some additional features such as hypotonia, microcephaly, developmental delay and/or intellectual disability, and family history of growth failure, were actually discordant with SRS in our cohort. CONCLUSIONS: The clinical resemblance of other short stature syndromes with SRS poses a risk of diagnostic failure, in particular when clinical SRS only criteria are met, allowing SRS diagnosis in the absence of a positive result of a genetic test. The presence of additional features atypical for SRS diagnosis becomes a red flag for a more extensive and thorough analysis. The signs relevant to the differential diagnosis should be valued as much as possible since a correct diagnosis of these patients is the only way to provide the appropriate care pathway, a thorough genetic counselling, prognosis definition, follow up setting, appropriate monitoring and care of possible medical problems.

Convergent dwarfism consequences of minipigs under independent artificial selections.

BACKGROUND: Currently, diverse minipigs have acquired a common dwarfism phenotype through independent artificial selections. Characterizing the population and genetic diversity in minipigs is important to unveil genetic mechanisms regulating their body sizes and effects of independent artificial selections on those genetic mechanisms. However, full understanding for the genetic mechanisms and phenotypic consequences in minipigs still lag behind. RESULTS: Here, using whole genome sequencing data of 41 pig breeds, including eight minipigs, we identified a large genomic diversity in a minipig population compared to other pig populations in terms of population structure, demographic signatures, and selective signatures. Selective signatures reveal diverse biological mechanisms related to body size in minipigs. We also found evidence for neural development mechanism as a minipig-specific body size regulator. Interestingly, selection signatures within those mechanisms containing neural development are also highly different among minipig breeds. Despite those large genetic variances, PLAG1, CHM, and ESR1 are candidate key genes regulating body size which experience different differentiation directions in different pig populations. CONCLUSIONS: These findings present large variances of genetic structures, demographic signatures, and selective signatures in the minipig population. They also highlight how different artificial selections with large genomic diversity have shaped the convergent dwarfism.

Craniofacial studies in chicken embryos confirm the pathogenicity of human FZD2 variants associated with Robinow syndrome.

Robinow syndrome is a rare disease caused by variants of seven WNT pathway genes. Craniofacial features include widening of the nasal bridge and jaw hypoplasia. We used the chicken embryo to test whether two missense human FZD2 variants (1301G>T, p.Gly434Val; 425C>T, p.Pro142Lys) were sufficient to change frontonasal mass development. In vivo, the overexpression of retroviruses with wild-type or variant human FZD2 inhibited upper beak ossification. In primary cultures, wild-type and variant human FZD2 significantly inhibited chondrogenesis, with the 425C>T variant significantly decreasing activity of a SOX9 luciferase reporter compared to that for the wild type or 1301G>T. Both variants also increased nuclear shuttling of ß-catenin (CTNNB1) and increased the expression of TWIST1, which are inhibitory to chondrogenesis. In canonical WNT luciferase assays using frontonasal mass cells, the variants had dominant-negative effects on wild-type FZD2. In non-canonical assays, the 425C>T variant failed to activate the reporter above control levels and was unresponsive to exogenous WNT5A. This is the first single amino acid change to selectively alter ligand binding in a FZD receptor. Therefore, FZD2 missense variants are pathogenic and could lead to the altered craniofacial morphogenesis seen in Robinow syndrome.

Fetal phenotype and diagnosis of autosomal dominant Robinow syndrome due to novel DVL1 variant.

Due to abnormal prenatal ultrasound findings of femoral shortening and flattened facial profile, a G2P0 pregnant patient underwent an amniocentesis at 15 weeks of gestation for proband-only exome sequencing. Bioinformatic filtering for genes included on the laboratory's extended skeletal dysplasia panel identified a heterozygous, likely pathogenic, frameshift variant in DVL1 NM_001330311.2:c.1575_1582dup; (p.Pro528ArgfsTer149). Pathogenic variants in DVL1 are associated with autosomal dominant Robinow syndrome (ADRS), a genetic disorder characterized by skeletal dysplasia with genital and craniofacial abnormalities. Prenatal ultrasound in the third trimester noted shortened long bones (first percentile for gestational age), macrocephaly with frontal bossing, short and upturned nose with a wide nasal root, triangular mouth, low pedal arches concerning for rocker-bottom feet, and ambiguous genitalia. A postnatal exam by Medical Genetics confirmed the prenatal findings in addition to hypertelorism, brachydactyly with broad thumbs and halluces, clinodactyly of second fingers, rigid gums with a frontal frenulum, and a sacral dimple. This case describes a novel variant in DVL1 identified in a fetus with prenatal and postnatal phenotypic features consistent with ADRS. To our knowledge, this is the first reported case of a prenatal molecular diagnosis of the dominant form of Robinow syndrome and the third case to describe prenatal ultrasound findings associated with this diagnosis.

Thyroid dysgenesis associated with dwarfism, osteoporosis and spontaneous fractures in a goat.

An 11-month-old female Saanen goat, weighing 12.7 kg, was taken to the Veterinary Hospital of the Federal University of Minas Gerais because of sternal recumbency. On clinical examination, the animal was much smaller than expected and had hair similar to that of puppies and areas of hyperpigmentation on the head and dorsocervical and dorsothoracic cranial regions. Radiographic examination revealed fractures in both femurs and severe generalized osteoporosis. Given the unfavourable prognosis, the animal was euthanized. Necropsy revealed generalized pallor, muscular atrophy of the pelvic limbs and little reserve of subcutaneous adipose tissue. Both femurs had complete and closed diaphyseal fractures. The second lumbar vertebra was severely reduced in length as a result of a fracture, with dorsal displacement of the vertebral body towards the vertebral canal and compression of the spinal cord. Long bones and vertebrae had severe cortical thinning, enlargement of the medullary canal and reduced resistance. The thyroid gland was not in its normal anatomical location. A pale red nodule (1.0 × 0.4 cm) in the serosa of the middle third of the trachea, close to the thoracic entrance, was confirmed as ectopic thyroid tissue. Microscopically, the bones had evidence of growth arrest and severe osteoporosis. The ectopic thyroid nodule was hyperplastic with severe hypertrophy of follicular cells. The spinal cord was compressed by vertebral fractures and had focally extensive and severe myelomalacia. Based on the pathological features, the case was diagnosed as thyroid dysgenesis characterized by eutopic thyroid agenesis and ectopic thyroid tissue, associated with interruption of bone growth with dwarfism, osteoporosis and spontaneous secondary fractures with compression of the lumbar spinal cord.

An unusual case of 17-hydroxylase deficiency presenting with short stature.

17α-Hydroxylase and 17,20-lyase are enzymes encoded by the CYP17A1 gene and are necessary for the production of cortisol and sex steroids. Females with 17α-hydroxylase deficiency usually present with primary amenorrhea and delayed puberty accompanied by hypertension and electrolyte imbalance. Here, we report the case of a 14-year-old female patient who presented with severe short stature and delayed puberty without any complaint suggestive of 17-hydroxylase enzyme deficiency. Laboratory test results showed low cortisol and dehydroepiandrosterone sulfate (DHEA-S) along with high luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Turner syndrome was excluded after genetic analysis showed a 46,XX karyotype, and 17α-hydroxylase deficiency was diagnosed by detecting a c.1319G>A (p.Arg440His) variation/alternation in the patient's CYP17A1 gene.

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.

B-cell immune deficiency in twin sisters expands the phenotype of MOPDI.

Microcephalic osteodysplastic primordial dwarfism type I (MOPDI) is a very rare and severe autosomal recessive disorder characterized by marked intrauterine growth retardation, skeletal dysplasia, microcephaly and brain malformations. MOPDI is caused by biallelic mutations in RNU4ATAC, a non-coding gene involved in U12-type splicing of 1% of the introns in the genome, which are recognized by their specific splicing consensus sequences. Here, we describe a unique observation of immunodeficiency in twin sisters with mild MOPDI, who harbor a novel n.108_126del mutation, encompassing part of the U4atac snRNA 3' stem-loop and Sm protein binding site, and the previously reported n.111G>A mutation. Interestingly, both twin sisters show mild B-cell anomalies, including low naive B-cell counts and increased memory B-cell and plasmablasts counts, suggesting partial and transitory blockage of B-cell maturation and/or excessive activation of naive B-cells. Hence, the localization of a mutation in stem II of U4atac snRNA, as observed in another RNU4ATAC-opathy with immunodeficiency, that is, Roifman syndrome (RFMN), is not required for the occurrence of an immune deficiency. Finally, we emphasize the importance of considering immunodeficiency in MOPDI management to reduce the risk of serious infectious episodes.

A monoallelic UXS1 variant associated with short-limbed short stature.

BACKGROUND: Serine residues in the protein backbone of heavily glycosylated proteoglycans are bound to glycosaminoglycans through a tetrasaccharide linker. UXS1 encodes UDP-glucuronate decarboxylase 1, which catalyzes synthesis of UDP-xylose, the donor of the first building block in the linker. Defects in other enzymes involved in formation of the tetrasaccharide linker cause so-called linkeropathies, characterized by short stature, radio-ulnar synostosis, decreased bone density, congenital contractures, dislocations, and more. METHODS: Whole exome sequencing was performed in a father and son who presented with a mild skeletal dysplasia, as well as the father's unaffected parents. Wild-type and mutant UXS1 were recombinantly expressed in Escherichia coli and purified. Enzyme activity was evaluated by LC-MS/MS. In vivo effects were studied using HeparinRed assay and metabolomics. RESULTS: The son had short long bones, normal epiphysis, and subtle metaphyseal changes especially in his legs. The likely pathogenic heterozygous variant NM_001253875.1(UXS1):c.557T>A p.(Ile186Asn) detected in the son was de novo in the father. Purified Ile186Asn-UXS1, in contrast to the wild-type, was not able to convert UDP-glucuronic acid to UDP-xylose. Plasma glycosaminoglycan levels were decreased in both son and father. CONCLUSION: This is the first report linking UXS1 to short-limbed short stature in humans.

Variants in both the N- or C-terminal domains of IHH lead to defective secretion causing short stature and skeletal defects.

BACKGROUND: Heterozygous Indian Hedgehog gene (IHH) variants are associated with brachydactyly type A1 (BDA1). However, in recent years, numerous variants have been identified in patients with short stature and more variable forms of brachydactyly. Many are located in the C-terminal domain of IHH (IHH-C), which lacks signaling activity but is critical for auto-cleavage and activation of the N-terminal (IHH-N) peptide. The absence of functional studies of IHH variants, particularly for those located in IHH-C, has led to these variants being classified as variants of uncertain significance (VUS). OBJECTIVE: To establish a simple functional assay to determine the pathogenicity of IHH VUS and confirm that variants in the C-terminal domain affect protein function. DESIGN/METHODS: In vitro studies were performed for 9 IHH heterozygous variants, to test their effect on secretion and IHH intracellular processing by western blot of cells expressing each variant. RESULTS: IHH secretion was significantly reduced in all mutants, regardless of the location. Similarly, intracellular levels of N-terminal and C-terminal IHH peptides were severely reduced in comparison with the control. Two variants present at a relatively high frequency in the general population also reduced secretion but to a lesser degree in the heterozygous state. CONCLUSIONS: These studies provide the first evidence that variants in the C-terminal domain affect the secretion capacity of IHH and thus, reduce availability of IHH ligand, resulting in short stature and mild skeletal defects. The secretion assay permits a relatively easy test to determine the pathogenicity of IHH variants. All studied variants affected secretion and interestingly, more frequent population variants appear to have a deleterious effect and thus contribute to height variation.

Short beak and dwarfism syndrome among Pekin ducks: First detection, full genome sequencing, and immunohistochemical signals of novel goose parvovirus in tongue tissue.

Novel goose parvovirus (NGPV) is continuously threatening the global duck industry, as it causes short beak and dwarfism syndrome among different duck breeds. In this study, we investigated the viral pathogenesis in the tongue of affected ducks, as a new approach for deeper understanding of the syndrome. Seventy-three, 14- to 60-day-old commercial Pekin ducks were clinically examined. Thirty tissue pools of intestine and tongue (15 per tissue) were submitted for molecular identification. Clinical signs in the examined ducks were suggestive of parvovirus infection. All examined ducks had short beaks. Necrotic, swollen, and congested protruding tongues were recorded in adult ducks (37/73, 51%). Tongue protrusion without any marked congestion or swelling was observed in 20-day-old ducklings (13/73, 18%), and no tongue protrusion was observed in 15-day-old ducklings (23/73, 32%). Microscopically, the protruding tongues of adult ducks showed necrosis of the superficial epithelial layer with vacuolar degeneration. Glossitis was present in the nonprotruding tongues of young ducks, which was characterized by multifocal lymphoplasmacytic aggregates and edema in the propria submucosa. Immunohistochemical examination displayed parvovirus immunolabeling, mainly in the tongue propria submucosa. Based on polymerase chain reaction, goose parvovirus was detected in 9 out of 15 tongue sample pools (60%). Next-generation sequencing confirmed the presence of a variant goose parvovirus that is globally named NGPV and closely related to Chinese NGPV isolates. Novel insights are being gained from the study of NGPV pathogenesis in the tongue based on molecular and immunohistochemical identification.

Novel biallelic PISD missense variants cause spondyloepimetaphyseal dysplasia with disproportionate short stature and fragmented mitochondrial morphology.

Biallelic variants in PISD cause a phenotypic spectrum ranging from short stature with spondyloepimetaphyseal dysplasia (SEMD) to a multisystem disorder affecting eyes, ears, bones, and brain. PISD encodes the mitochondrial-localized enzyme phosphatidylserine decarboxylase. The PISD precursor is self-cleaved to generate a heteromeric mature enzyme that converts phosphatidylserine to the phospholipid phosphatidylethanolamine. We describe a 17-year-old male patient, born to unrelated healthy parents, with disproportionate short stature and SEMD, featuring platyspondyly, prominent epiphyses, and metaphyseal dysplasia. Trio genome sequencing revealed compound heterozygous PISD variants c.569C>T; p.(Ser190Leu) and c.799C>T; p.(His267Tyr) in the patient. Investigation of fibroblasts showed similar levels of the PISD precursor protein in both patient and control cells. However, patient cells had a significantly higher proportion of fragmented mitochondria compared to control cells cultured under basal condition and after treatment with 2-deoxyglucose that represses glycolysis and stimulates respiration. Structural data from the PISD orthologue in Escherichia coli suggest that the amino acid substitutions Ser190Leu and His267Tyr likely impair PISD's autoprocessing activity and/or phosphatidylethanolamine biosynthesis. Based on the data, we propose that the novel PISD p.(Ser190Leu) and p.(His267Tyr) variants likely act as hypomorphs and underlie the pure skeletal phenotype in the patient.

Clinical and genetic investigation of 14 families with various forms of short stature syndromes.

Skeletal dysplasias are a heterogeneous group of disorders presenting mild to lethal defects. Several factors, such as genetic, prenatal, and postnatal environmental may contribute to reduced growth. Fourteen families of Pakistani origin, presenting the syndromic form of short stature either in the autosomal recessive or autosomal dominant manner were clinically and genetically investigated to uncover the underlying genetic etiology. Homozygosity mapping, whole exome sequencing, and Sanger sequencing were used to search for the disease-causing gene variants. In total, we have identified 13 sequence variants in 10 different genes. The variants in the HSPG2 and XRCC4 genes were not reported previously in the Pakistani population. This study will expand the mutation spectrum of the identified genes and will help in improved diagnosis of the syndromic form of short stature in the local population.

Cartilage-hair hypoplasia-anauxetic dysplasia spectrum disorders harboring RMRP mutations in two Korean children: A case report.

RATIONALE: Cartilage-hair hypoplasia (CHH, OMIM # 250250) is a rare autosomal recessive disorder, which includes cartilage-hair hypoplasia-anauxetic dysplasia (CHH-AD) spectrum disorders. CHH-AD is caused by homozygous or compound heterozygous mutations in the RNA component of the mitochondrial RNA-processing Endoribonuclease (RMRP) gene. PATIENT CONCERNS: Here, we report 2 cases of Korean children with CHH-AD. DIAGNOSES: In the first case, the patient had metaphyseal dysplasia without hypotrichosis, diagnosed by whole exome sequencing (WES), and exhibited only skeletal dysplasia and lacked extraskeletal manifestations, such as hair hypoplasia and immunodeficiency. In the second case, the patient had skeletal dysplasia, hair hypoplasia, and immunodeficiency, which were identified by WES. INTERVENTIONS: The second case is the first CHH reported in Korea. The patients in both cases received regular immune and lung function checkups. OUTCOMES: Our cases suggest that children with extremely short stature from birth, with or without extraskeletal manifestations, should include CHH-AD as a differential diagnosis. LESSONS SUBSECTIONS: Clinical suspicion is the most important and RMRP sequencing should be considered for the diagnosis of CHH-AD.