MIA3 Splice Defect in Cane Corso Dogs with Dental-Skeletal-Retinal Anomaly (DSRA).

We investigated a hereditary syndrome in Cane Corso dogs. Affected dogs developed dental-skeletal-retinal anomaly (DSRA), clinically characterized by brittle, discolored, translucent teeth, disproportionate growth and progressive retinal degeneration resulting in vision loss. Combined linkage and homozygosity mapping delineated a 5.8 Mb critical interval. The comparison of whole genome sequence data of an affected dog to 789 control genomes revealed a private homozygous splice region variant in the critical interval. It affected the MIA3 gene encoding the MIA SH3 domain ER export factor 3, which has an essential role in the export of collagen and other secreted proteins. The identified variant, XM_005640835.3:c.3822+3_3822+4del, leads to skipping of two exons from the wild type transcript, XM_005640835.3:r.3712_3822del. Genotypes at the variant were consistent with monogenic autosomal recessive mode of inheritance in a complete family and showed perfect genotype-phenotype association in 18 affected and 22 unaffected Cane Corso dogs. MIA3 variants had previously been shown to cause related phenotypes in humans and mice. Our data in dogs together with the existing functional knowledge of MIA3 variants in other mammalian species suggest the MIA3 splice defect and a near complete loss of gene function as causative molecular pathomechanism for the DSRA phenotype in the investigated dogs.

Skeletal Deformities in Osterix-Cre;Tgfbr2f/f Mice May Cause Postnatal Death.

Transforming growth factor ß (TGFß) signaling plays an important role in skeletal development. We previously demonstrated that the loss of TGFß receptor II (Tgfbr2) in Osterix-Cre-expressing mesenchyme results in defects in bones and teeth due to reduced proliferation and differentiation in pre-osteoblasts and pre-odontoblasts. These Osterix-Cre;Tgfbr2f/f mice typically die within approximately four weeks for unknown reasons. To investigate the cause of death, we performed extensive pathological analysis on Osterix-Cre- (Cre-), Osterix-Cre+;Tgfbr2f/wt (HET), and Osterix-Cre+;Tgfbr2f/f (CKO) mice. We also crossed Osterix-Cre mice with the ROSA26mTmG reporter line to identify potential off-target Cre expression. The findings recapitulated published skeletal and tooth abnormalities and revealed previously unreported osteochondral dysplasia throughout both the appendicular and axial skeletons in the CKO mice, including the calvaria. Alterations to the nasal area and teeth suggest a potentially reduced capacity to sense and process food, while off-target Cre expression in the gastrointestinal tract may indicate an inability to absorb nutrients. Additionally, altered nasal passages and unexplained changes in diaphragmatic muscle support the possibility of hypoxia. We conclude that these mice likely died due to a combination of breathing difficulties, malnutrition, and starvation resulting primarily from skeletal deformities that decreased their ability to sense, gather, and process food.

An intrafamilial phenotypic variability in Ellis-Van Creveld syndrome due to a novel 27 bps deletion mutation.

Ellis-van Creveld (EvC) syndrome is an autosomal recessive disease, characterized by ectodermal, skeletal, and cardiac anomalies. We report intrafamilial phenotypic variability in three new EvC syndrome cases. Affected males in this study showed only ectodermal abnormalities, whereas an affected female showed the classical presentation of EvC Syndrome, including bilateral postaxial polydactyly of hands and feet, and congenital heart defects. Whole exome sequencing was performed to identify the causative variant, followed by validation and segregation analysis using Sanger sequencing. A homozygous deletion variant (c.731_757del) was identified in exon 6 of the EVC gene (NM_153717.2). The identified variant is considered to be the most likely candidate variant for the EvC syndrome in the family based on previous reports validating the role of EVC variants in the EvC syndrome. The disease correctly segregated in the family members, as all affected members were homozygous, and obligate carriers were heterozygous. Our family is remarkable in highlighting the variable expressivity of the EvC phenotype within the same family, due to a homozygous deletion mutation in the EVC gene. The variable expressivity might be due to the hypomorphic nature of mutation, or the presence of additional variants in modifier genes or in the regulatory regions of the EVC/EVC2 genes.

Skeletal deformities and meristic trait variations are common in the intertidal fish Bathygobius cocosensis (Perciformes-Gobiidae).

Extreme environmental conditions, such as temperature, can lead to meristic trait variation and skeletal deformities, which may have major impacts on individual fitness. As intertidal ecosystems experience rapid temperature and physicochemical fluctuations, intertidal fish living and reproducing in these environmental conditions may have phenotypes influenced by such variable environments. The impact of intertidal variability on fish development, however, has not been previously investigated. Skeletal deformities and meristic traits were assessed for Bathygobius cocosensis, a common intertidal fish living across the Indo-Pacific region, using a clearing and staining method on 72 individuals. Over 87% of individuals presented meristic variation and over 70% exhibited at least one type of skeletal deformity, mostly recorded in the caudal fin area. The unexpected prevalence of skeletal deformities among this intertidal fish population suggests that such deformities may be suitable markers to evaluate an individual's stress exposure during development and the subsequent fitness effects.

Consideraciones bucodentales en pacientes con Síndrome de Morquio / Dental considerations of the morquio síndrome

La mucopolisacaridosis tipo IV (MPS-IV) también conocida como enfermedad de Morquio en recuerdo del pediatra uruguayo Luis Morquio que la describió por primera vez, es una enfermedad congénita causada por la deficiencia de la enzima N-acetilgalactosamina 6 sulfatasa o de la enzima B-Galactosidasa. Estas anomalías enzimáticas tienen como consecuencia que se acumulen en diferentes tejidos del organismo cantidades elevadas de mucopolisacaridos. En la bibliografía se describe con detalle los defectos del esmalte que presentan los pacientes diagnosticados del síndrome de Morquio. Estos defectos son una característica aparentemente constante en la enfermedad y, por lo tanto, hace necesaria las visitas al odontólogo para su control evitándose problemas mayores. Dichos defectos consisten en un esmalte anormalmente delgado, que es áspero debido a los numerosos hoyos diminutos y a una superficie irregular. La delgadez del esmalte da como resultado una forma alterada y decoloración de los dientes que, añadido a los diastemas interdentales, provocan alteraciones en la oclusión. Aparte de estos defectos, el esmalte es histológicamente normal y tiene una du-reza y radiodensidad normales. El trata-miento odontológico de los pacientes con MPS-IV requiere colaboración multidisciplinar, debido a que las manifestaciones orales de la enfermedad pueden aparecer a cualquier edad, resultando en ocasiones tedioso para el paciente y complicado para el profesional. Especial mención merecen las terapias utilizadas como trata-miento sintomático de la enfermedad, así como el manejo de la vía aérea en el caso de intervenciones bajo anestesia general o sedación para tratar ciertas patologías del territorio bucomaxilodental

Mucopolysaccharidosis type IV (MPS-IV) also known as Morquio’s disease in memory of the Uruguayan pediatrician Luis Morquio who described it for the first time, is a congenital disease caused by the deficiency of the enzyme N-acetylgalactosamine 6 sulfatase or enzyme B -Galactosidase. These enzymatic anomalies result in high amounts of mucopolysaccharides accumulating in different tissues of the organism. The enamel defects presented by patients diagnosed with Morquio syndrome are described in detail in the bibliography. These defects are an apparently constant feature in the disease and, therefore, make visits to the dentist necessary for their control, avoiding major problems. These defects consist of an abnormally thin enamel that is rough due to numerous tiny holes and an irregular surface. The thinness of the enamel results in an altered form and discoloration of the teeth, which added to the interdental diastemas, cause alterations in the occlusion. Apart from these defects, the enamel is histologically normal and has a normal hardness and radiodensity.Dental treatment of patients with MPS-IV requires multidisciplinary collaboration, because the oral manifestations of the disease can appear at any age, being sometimes tedious for the patient and complicated for the professional. Special mention should be made of the therapies used as a symptomatic treatment of the disease, as well as the management of the airway in the case of interventions under general anesthesia or sedation to treat certain pathologies of the bucomaxillodental territory

Ambroxol improves skeletal and hematological manifestations on a child with Gaucher disease.

Gaucher disease (GD) is a lysosomal storage disease caused by the deficiency of glucocerebrosidase characterized by a broad spectrum of clinical manifestations including hepatosplenomegaly, bone infiltration, and cytopenia, and even central nervous system involvement. Bone manifestations are typical of the GD-I and partially responded to mainstay therapy. Ambroxol (ABX), an approved cough-suppressant, was identified as an enzyme-enhancement agent of the residual activity of glucocerebrosidase mutants derived from different misfolding-mutations in the GBA gene. Here, we describe the early beneficial effects of ABX on skeletal and hematological manifestations of a child suffering with progressive GD-I.

Expanding the clinical and molecular spectrum of the CWC27-related spliceosomopathy.

Cyclophilins are a type of peptidyl-prolyl cis-trans isomerases. CWC27, one of the known human cyclophilins, is recruited by the spliceosome for the pre-mRNA splicing process. Biallelic deleterious variants in CWC27 lead to a spectrum of overlapping phenotypes including retinal degeneration, skeletal anomalies, short stature, and neurological defects. The present work reports a woman showing these clinical features, in addition to hypergonadotropic hypogonadism, hypoplastic/agenesic teeth, and cataracts, not previously associated with such phenotypic spectrum. Whole exome sequencing on this patient identified a novel CWC27 homozygous variant predicted to originate a severely truncated protein and the consequent loss of functionality. The clinical and genetic characterization of such patient could provide further insight into the underlying causes of the spliceosomopathies.

Cerebrofaciothoracic dysplasia: Four new patients with a recurrent TMCO1 pathogenic variant.

Biallelic loss of function variants in the TMCO1 gene have been previously demonstrated to result in cerebrofaciothoracic dysplasia (CFTD; MIM #213980). The phenotype of this condition includes severe intellectual disability, as well as distinctive craniofacial features, including brachycephaly, synophrys, arched eyebrows, "cupid's bow" upper lip, and microdontia. In addition, nonspecific skeletal anomalies are common, including bifid ribs, scoliosis, and spinal fusion. Only 19 molecularly confirmed patients have been previously described. Here, we present four patients with CFTD, including three brothers from a Pakistani background and an additional unrelated white Scottish patient. All share the characteristic craniofacial appearance, with severe intellectual disability and skeletal abnormalities. We further define the phenotype with comparison to the published literature, and present images to define the dysmorphic features in a previously unreported ethnic group. All of our patient series are homozygous for the same c.292_293del (p.Ser98*) TMCO1 pathogenic variant, which has been previously reported only in an isolated Amish population. Thus we provide evidence that CFTD may be more common than previously thought. The patients presented here further delineate the phenotypic spectrum of CFTD and provide evidence for a recurrent pathogenic variant in TMCO1.

Early Transition to Microdiets Improves Growth, Reproductive Performance and Reduces Skeletal Anomalies in Zebrafish (Danio rerio).

Zebrafish is a model species with a high variability of feeding regimes among fish facilities. The use of live feeds for early life stages is a common practice, and few studies have focused early weaning into microdiets. The lack of standardized feeding protocols among research facilities promotes discrepancies in biological performances, and few studies relate dietary regimes to zebrafish development. The objective of this work was to assess the effect of an early transition into microdiets in zebrafish development by evaluating growth, survival, reproductive performance, and skeletal anomalies. These parameters were assessed in one group exclusively fed on Artemia nauplii and two groups fed on microdiets (commercial and experimental). Results showed that an early weaning with the two microdiets significantly improved zebrafish growth and reproductive performance, while a decrease in incidence of vertebral column anomalies was observed. A high survival was also maintained in fish fed microdiets at an early developmental stage when comparing to exclusive Artemia nauplii feeding. In conclusion, early weaning with high quality microdiets is beneficial for zebrafish growth, reproductive performance, and skeletal development, contributing to the standardization of zebrafish husbandry practices.

An abundance of developmental anomalies and abnormalities in Pleistocene people.

Diverse developmental abnormalities and anomalous features are evident in the Pleistocene Homo fossil record, varying from minor but rare dental, vertebral, and carpal variants to exceptional systemic disorders. There are currently 75 documented anomalies or abnormalities from 66 individuals, spanning the Pleistocene but primarily from the Late Pleistocene Middle and Upper Paleolithic with their more complete skeletal remains. The expected probabilities of finding these variants or developmental disorders vary from <5% to <0.0001%, based on either recent human incidences or relevant Pleistocene sample distributions. Given the modest sample sizes available for the skeletal or dental elements in question, especially if the samples are appropriately limited in time and geography, the cumulative multiplicative probability of finding these developmental changes is vanishingly small. These data raise questions regarding social survival abilities, differing mortuary treatments of the biologically unusual, the role of ubiquitous stress among these Pleistocene foragers, and their levels of consanguinity. No single factor sufficiently accounts for the elevated level of these developmental variants or the low probability of finding them in the available paleontological record.

Notch in skeletal physiology and disease.

Notch (Notch1 through 4) are transmembrane receptors that play a fundamental role in cell differentiation and function. Notch receptors are activated following interactions with their ligands in neighboring cells. There are five classic ligands termed Jagged (Jag)1 and Jag2 and Delta-like (Dll)1, Dll3, and Dll4. Recent work has established Notch as a signaling pathway that plays a critical role in the differentiation and function of cells of the osteoblast and osteoclast lineages and in skeletal development and bone remodeling. The effects of Notch are cell-context dependent, and the four Notch receptors carry out specific functions in the skeleton. Gain- and loss-of-function mutations of components of the Notch signaling pathway result in a variety of congenital disorders with significant craniofacial and skeletal manifestations. The Notch ligand Jag1 is a determinant of bone mineral density, and Notch plays a role in the early phases of fracture healing. Alterations in Notch signaling are associated with osteosarcoma and with the metastatic potential of carcinoma of the breast and of the prostate. Controlling Notch signaling could prove useful in diseases of Notch gain-of-function and in selected skeletal disorders. However, clinical data on agents that modify Notch signaling are not available. In conclusion, Notch signaling is a novel pathway that regulates skeletal homeostasis in health and disease.

A novel association of campomelic dysplasia and hydrocephalus with an unbalanced chromosomal translocation upstream of SOX9.

Campomelic dysplasia is a rare skeletal dysplasia characterized by Pierre Robin sequence, craniofacial dysmorphism, shortening and angulation of long bones, tracheobronchomalacia, and occasionally sex reversal. The disease is due to mutations in SOX9 or chromosomal rearrangements involving the long arm of Chromosome 17 harboring the SOX9 locus. SOX9, a transcription factor, is indispensible in establishing and maintaining neural stem cells in the central nervous system. We present a patient with angulation of long bones and external female genitalia on prenatal ultrasound who was subsequently found to harbor the chromosomal abnormality 46, XY, t(6;17) (p21.1;q24.3) on prenatal genetic testing. Comparative genomic hybridization revealed deletions at 6p21.1 and 17q24.3, the latter being 2.3 Mb upstream of SOX9 Whole-exome sequencing did not identify pathogenic variants in SOX9, suggesting that the 17q24.3 deletion represents a translocation breakpoint farther upstream of SOX9 than previously identified. At 2 mo of age the patient developed progressive communicating ventriculomegaly and thinning of the cortical mantle without clinical signs of increased intracranial pressure. This case suggests ventriculomegaly in some cases represents not a primary impairment of cerebrospinal fluid dynamics, but an epiphenomenon driven by a genetic dysregulation of neural progenitor cell fate.

Maternal and developmental toxicity of the hallucinogenic plant-based beverage ayahuasca in rats.

Rats were treated orally with ayahuasca (AYA) on gestation days (GD) 6-20 at doses corresponding to one-(1X) to eight-fold (8X) the average dose taken by a human adult in a religious ritual, and the pregnancy outcome evaluated on GD21. Rats treated with 4X and 8X doses died during the treatment period (44 and 52%), and those that survived showed kidney injury. Rats surviving the 8X dose showed neuronal loss in hippocampal regions and in the raphe nuclei, and those from the 2X dose neuronal loss in CA1. Delayed intrauterine growth, induced embryo deaths and increased occurrence of foetal anomalies were observed at the 8X dose. At non-lethal doses, AYA enhanced embryolethality and the incidence of foetal soft-tissue and skeleton anomalies. This study suggested that AYA is developmentally toxic and that its daily use by pregnant women may pose risks for the conceptus.

Expanding the genetic architecture and phenotypic spectrum in the skeletal ciliopathies.

Defects in the biosynthesis and/or function of primary cilia cause a spectrum of disorders collectively referred to as ciliopathies. A subset of these disorders is distinguished by profound abnormalities of the skeleton that include a long narrow chest with markedly short ribs, extremely short limbs, and polydactyly. These include the perinatal lethal short-rib polydactyly syndromes (SRPS) and the less severe asphyxiating thoracic dystrophy (ATD), Ellis-van Creveld (EVC) syndrome, and cranioectodermal dysplasia (CED) phenotypes. To identify new genes and define the spectrum of mutations in the skeletal ciliopathies, we analyzed 152 unrelated families with SRPS, ATD, and EVC. Causal variants were discovered in 14 genes in 120 families, including one newly associated gene and two genes previously associated with other ciliopathies. These three genes encode components of three different ciliary complexes; FUZ, which encodes a planar cell polarity complex molecule; TRAF3IP1, which encodes an anterograde ciliary transport protein; and LBR, which encodes a nuclear membrane protein with sterol reductase activity. The results established the molecular basis of SRPS type IV, in which mutations were identified in four different ciliary genes. The data provide systematic insight regarding the genotypes associated with a large cohort of these genetically heterogeneous phenotypes and identified new ciliary components required for normal skeletal development.

Stage specific requirement of platelet-derived growth factor receptor-α in embryonic development.

BACKGROUND: Platelet-derived growth factor receptor alpha (PDGFRα) is a cell-surface receptor tyrosine kinase for platelet-derived growth factors. Correct timing and level of Pdgfra expression is crucial for embryo development, and deletion of Pdgfra caused developmental defects of multiple endoderm and mesoderm derived structures, resulting in a complex phenotypes including orofacial cleft, spina bifida, rib deformities, and omphalocele in mice. However, it is not clear if deletion of Pdgfra at different embryonic stages differentially affects these structures. PURPOSE: To address the temporal requirement of Pdgfra in embryonic development. METHODS: We have deleted the Pdgfra in Pdgfra-expressing tissues at different embryonic stages in mice, examined and quantified the developmental anomalies. RESULTS: Current study showed that (i) conditional deletion of Pdgfra at different embryonic days (between E7.5 and E10.5) resulted in orofacial cleft, spina bifida, rib cage deformities, and omphalocele, and (ii) the day of Pdgfra deletion influenced the combinations, incidence and severities of these anomalies. Deletion of Pdgfra caused apoptosis of Pdgfra-expressing tissues, and developmental defects of their derivatives. CONCLUSION: Orofacial cleft, spina bifida and omphalocele are among the commonest skeletal and abdominal wall defects of newborns, but their genetic etiologies are largely unknown. The remarkable resemblance of our conditional Pdgfra knockout embryos to theses human congenital anomalies, suggesting that dysregulated PDGFRA expression could cause these anomalies in human. Future work should aim at defining (a) the regulatory elements for the expression of the human PDGFRA during embryonic development, and (b) if mutations / sequence variations of these regulatory elements cause these anomalies.

Differences between NMRI and DBA/2J mice in the development of somites and susceptibility to methylnitrosourea-induced skeleton anomalies.

The development of DBA/2J mouse strain embryos is nearly 12 h - or 6 somite pairs - delayed as compared to the outbred NMRI mouse embryos of the same age on gestation days (GD) 8-12. To evaluate inter-strain differences in susceptibility to teratogens, dams were treated with methylnitrosourea (MNU, 5 mg/kg body weight i.p.) on defined gestation days (NMRI: GD 9, 91/2 or 10; DBA/2J: GD 10 or 101/2). Skeletal anomalies produced by MNU on both mouse strains varied with the GD of treatment. The pattern of anomalies produced by MNU on a given GD markedly differed between the two mouse strains, yet they were similar -with a few exceptions- when exposures at equivalent embryonic stages are compared. Findings from this study indicated that strain-dependent differences in the developmental stage of mouse embryos of the same gestational age occur, a possibility that has been often neglected when inter-strain differences in susceptibility to developmental toxicants are interpreted.

Effects of maternal hypoglycemia on fetal eye and skeleton development in rats.

The relationship between insulin-induced maternal hypoglycemia and teratogenicity was investigated in detail. We injected 4 different forms of insulin (insulin human, aspart, glargine, and detemir) subcutaneously at 1 or 2 dose levels to Sprague-Dawley rats from Days 6 to 11 of pregnancy, measured blood glucose levels, and conducted fetal examination. In the insulin human and aspart (low dose) groups, while severe hypoglycemia (approximately 50mg/dL) was seen, it lasted only 6h and no fetal anomalies were observed. Fetal axial skeleton anomalies were observed in the aspart (high dose) group, which exhibited intermediate-duration of severe hypoglycemia (9h). Eye and axial skeleton anomalies were observed in the glargine and detemir groups, which exhibited continuous severe hypoglycemia (≥9h). These results revealed that insulin-induced maternal hypoglycemia caused fetal eye and skeleton anomalies and the causative key factors were duration of maternal severe hypoglycemia.

Differences between NMRI and DBA/2J mice in the development of somites and susceptibility to methylnitrosourea-induced skeleton anomalies

ABSTRACT The development of DBA/2J mouse strain embryos is nearly 12 h - or 6 somite pairs - delayed as compared to the outbred NMRI mouse embryos of the same age on gestation days (GD) 8-12. To evaluate inter-strain differences in susceptibility to teratogens, dams were treated with methylnitrosourea (MNU, 5 mg/kg body weight i.p.) on defined gestation days (NMRI: GD 9, 91/2 or 10; DBA/2J: GD 10 or 101/2). Skeletal anomalies produced by MNU on both mouse strains varied with the GD of treatment. The pattern of anomalies produced by MNU on a given GD markedly differed between the two mouse strains, yet they were similar -with a few exceptions- when exposures at equivalent embryonic stages are compared. Findings from this study indicated that strain-dependent differences in the developmental stage of mouse embryos of the same gestational age occur, a possibility that has been often neglected when inter-strain differences in susceptibility to developmental toxicants are interpreted.

The First Scube3 Mutant Mouse Line with Pleiotropic Phenotypic Alterations.

The vertebrate Scube (Signal peptide, CUB, and EGF-like domain-containing protein) family consists of three independent members, Scube1-3, which encode secreted cell surface-associated membrane glycoproteins. Limited information about the general function of this gene family is available, and their roles during adulthood. Here, we present the first Scube3 mutant mouse line (Scube3N294K/N294K), which clearly shows phenotypic alterations by carrying a missense mutation in exon 8, and thus contributes to our understanding of SCUBE3 functions. We performed a detailed phenotypic characterization in the German Mouse Clinic (GMC). Scube3N294K/N294K mutants showed morphological abnormalities of the skeleton, alterations of parameters relevant for bone metabolism, changes in renal function, and hearing impairments. These findings correlate with characteristics of the rare metabolic bone disorder Paget disease of bone (PDB), associated with the chromosomal region of human SCUBE3 In addition, alterations in energy metabolism, behavior, and neurological functions were detected in Scube3N294K/N294K mice. The Scube3N294K/N294K mutant mouse line may serve as a new model for further studying the effect of impaired SCUBE3 gene function.

The constellation of skeletal deformities in a family with mixed types of mucopolysaccharidoses: Case report.

INTRODUCTION: A 13-year-old child was clinically diagnosed with mucopolysaccharidosis type VI-Maroteaux-Lamy syndrome (MPS VI) at the age of 5 years, and the diagnosis was confirmed biochemically and genetically (homozygous mutation in ARSB gene). At that time, his older brother manifested with increasing severe mental retardation. His urinary glycosaminoglycan excretion in urine was elevated, but there was only 1 mutation in the ARSB gene defining him as a healthy carrier of MPS VI. The 15-year-old boy was born with dysmorphic facial features, cleft lip and palate, and multiple contractures associated with profound skeletal deformities manifested, severe mental retardation, and seizures, leading to the diagnosis of cerebral palsy from birth on.Clinical and radiographic phenotypic characterization was the baseline tool to document the older sibling, parents, and relatives, all of them examined at the Orthopaedic Hospital of Speising, Vienna, Austria. The family history (from maternal and paternal sides) showed >10 subjects with variable clinical histories of hyperactivity and attention deficit disorder, depression, and a diversity of skeletal abnormalities, such as dysplastic spondylolisthesis, discovertebral degeneration, osteopenia, osteophytosis, and progressive degeneration of the weight bearing zones (mostly developed at middle age). METHODS: Eleven patients in a family with interrelated marriages (two male siblings of 15 and 13-year-old), parents and relatives over three generations were enrolled. One of the siblings was diagnosed with Maroteaux-Lamy syndrome at the age of five-years and mutation of the ARBS gene has been encountered. The older sibling manifested at birth craniofacial abnormalities associated with multiple contracture and seizures. Cerebral palsy was the suggested diagnosis. Clinical and radiographic phenotypes were the baseline tool to document the older sibling, parents and relatives at the orthopaedic Hospital of Speising, Vienna, Austria. These were followed by whole Exome sequencing in three family subjects. RESULTS: A series of genetic studies in the older sibling showed homozygous mutation in GNS gene compatible with MPS IIID. Both parents are first related and were found to be heterozygous for N-acetylglucosamine-6-sulfatase GNS gene. Family history showed more than 10 subjects with variable clinical presentations such as dysplastic spondylolisthesis, disco-vertebral degeneration, osteopenia, osteophytosis, and progressive degeneration of the weight bearing zones (mostly developed at middle age). CONCLUSION: Owing to the multiple systemic involvements, a genetic cause was suspected and a molecular genetic investigation by using whole-exome-sequencing method in 3 family subjects (trios) was performed: the 15-year-old boy and his parents. A homozygous splice-site-mutation in the GNS gene could be found, compatible with mucopolysaccharidosis-Sanfillipo syndrome (type IIID). Both parents are first related and were now found also to be heterozygous for the GNS gene mutation found in their older son. Therefore, both parents are heterozygous carriers for the ARSB gene mutation but also the GNS gene mutation. In the son with MPS VI, no mutation in the GNS gene was found, but the brother with MPS IIID was heterozygous for the ARSB gene mutation.We presume that the intrafamilial variability of clinical signs in different family members could be the result of various mutations in the ARSB/GNS genes in the carriers or potential modulating effects of other genes or differences in genetic backgrounds.