X-linked Spondyloepiphyseal Dysplasia Tarda Research Articles

SPONDİLOEPİ (META) FİZYAL DİSPLAZİ ÖN TANILI BEŞ TÜRK ERKEK HASTADAKİ GENETİK ETYOLOJİNİN ARAŞTIRILMASI

OBJECTIVE: Skeletal dysplasias is a complex disease group characterized by disproportionate short stature and various orthopedic complications. X-Linked Spondyloepiphyseal Dysplasia Tarda is an X-linked inherited skeletal dysplasia accompanied by progressive spondyloepi(meta)physeal dysplasia and premature osteoartritis. The gene related to the disorder is trafficking protein particle complex 2 (TRAPPC2). Progressive pseudorheumatoid dysplasia (PPRD) is characterized by enlargement of the elbow joints and arthritis-like findings. It is an autosomal recessive subtype of skeletal dysplasia caused by mutations in cellular communication network factor 6 (CCN6) gene located on chrosomal region 6q21. In this study, it was aimed to diagnose five male individuals with an X-linked or autosomal recessive inheritance pattern, who have not been diagnosed for years, to identify possible treatments and to offer prenatal pmreimplantation genetic testing. MATERIAL AND METHODS: Five male siblings with skeletal dysplasia with an uncertain inheritance either X-linked or autosomal recessive pattern were included in this study, Whole Exome Sequencing (WES) was applied to the four affected cases. Sanger Sequencing was performed in one affected case and four healthy individuals. RESULTS: Homozygous c.210C>A (p.Cys70Ter) and homozygous c.302G>A (p.Gly101Glu) mutations in the CCN6 gene were found in all affected siblings. Thus, the final diagnosis after WES was autosomal recessive PPRD despite the possibility of an X-linked recessive pattern. CONCLUSIONS: This study presents a series of the oldest patients diagnosed with Progressive pseudorheumatoid dysplasia, normally a childhood disease, with an average age of 54.6. The p.Cys70Ter alteration is the most frequent pathogenic variant in Turkish patients. This study is also important in terms of showing that Progressive pseudorheumatoid dysplasia has no significant effect on life expectancy. At the same time, this study shows the progression of this disease and clinical findings that may accompany lifetime.

Growth hormone therapy in a boy with X-linked spondyloepiphyseal dysplasia tarda: a 3-year observation.

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Novel loss-of-function variants of TRAPPC2 manifesting X-linked spondyloepiphyseal dysplasia tarda: report of two cases

BackgroundX-linked spondyloepiphyseal dysplasia tarda (SEDT-XL) is a skeletal disorder characterized by defective structures of vertebral bodies and/or of epiphyses of the long bones, resulting in moderately short stature and early joint degeneration. TRAPPC2 gene, which is important for collagen secretion, has been reported as causative for SEDT-XL.Case presentationHere, we report two variants of TRAPPC2 gene of SEDT-XL patients, a missense variant of start codon, c.1A > T, and a deletion variant, c.40delG. To understand molecular consequence of the variants, we establish an in vitro gene expression assay system and demonstrate that both mutated genes are transcribed, but are not properly translated, indicative of the pathogenic nature of those TRAPPC2 variants.ConclusionsIn the current study, we provide additional experimental data showing that loss-of-function TRAPPC2 variants are probably causative for SEDT-XL phenotype. These findings further contribute to the understanding the clinical picture related to TRAPPC2 gene.

Clinical Diagnosis of X-Linked Spondyloepiphyseal Dysplasia Tarda and a Novel Missense Mutation in the Sedlin Gene (SEDL).

Objective Spondyloepiphyseal dysplasia tarda (SEDT) is a rare hereditary bone disease characterized by spinal and epiphyseal anomalies. We identified the disease by gene sequencing in a Chinese pedigree with SEDT. Methods We extracted genomic DNA from five members of a four-generation Chinese SEDT kindred with three affected males and then analyzed the genetic mutation by PCR and DNA sequencing. Results DNA sequencing showed that the genetic missense mutation occurred one bp upstream of exon 6 in the SEDL gene in two families, and a heterozygous mutation was found in a female carrier. In addition, no mutation was found in the other members of the family. Conclusion SEDT in this family was caused by a G/C missense mutation in exon 6 of the SEDL gene, previously not shown to be associated with X-linked SEDT.

Novel and Recurrent Mutations in the FGFR3 Gene and Double Heterozygosity Cases in a Cohort of Brazilian Patients with Skeletal Dysplasia

Mutations in the fibroblast growth factor receptor 3 gene (FGFR3) cause achondroplasia (ACH), hypochondroplasia (HCH), and thanatophoric dysplasia types I and II (TDI/TDII). In this study, we performed a genetic study of 123 Brazilian patients with these phenotypes. Mutation hotspots of the FGFR3 gene were PCR amplified and sequenced. All cases had recurrent mutations related to ACH, HCH, TDI or TDII, except for 2 patients. One of them had a classical TDI phenotype but a typical ACH mutation (c.1138G>A) in combination with a novel c.1130T>C mutation predicted as being pathogenic. The presence of the second c.1130T>C mutation likely explained the more severe phenotype. Another atypical patient presented with a compound phenotype that resulted from a combination of ACH and X-linked spondyloepiphyseal dysplasia tarda (OMIM 313400). Next-generation sequencing of this patient's DNA showed double heterozygosity for a typical de novo ACH c.1138G>A mutation and a maternally inherited TRAPPC2 c.6del mutation. All mutations were confirmed by Sanger sequencing. A pilot study using high-resolution melting (HRM) technique was also performed to confirm several mutations identified through sequencing. We concluded that for recurrent FGFR3 mutations, HRM can be used as a faster, reliable, and less expensive genotyping test than Sanger sequencing.

Mutation analysis of the TRAPPC2 gene in a Chinese family with X-linked spondyloepiphyseal dysplasia tarda

To identify potential mutation of TRAPPC2 gene in a Chinese family affected with X-linked spondyloepiphyseal dysplasia tarda (X-SEDL), and explore its underlying molecular mechanism. Peripheral blood samples were collected from 32 members of the family and 50 healthy adults to extract genomic DNA. DNA sequences of exons 3 to 6 and their exon/intron boundaries were amplified with PCR amplification. Direct bi-directional sequencing analysis was performed on the PCR products. The sequences were aligned to the reference sequences from the GenBank to determine mutation site and type. A nucleotide substitution of the splice-donor in TRAPPC2 intron 3, c.93+5G>A, was detected in the proband, but no sequence change was detected in TRAPPC2 exons 3 to 6. All of the 6 male patients and 8 female carriers from the family were detected to have carried this mutation. The same mutation was not found in the remaining 18 family members with a normal phenotype and 50 healthy controls. We have detected a c.93+5G>A mutation in the TRAPPC2 gene in a Chinese family affected with X-SEDL. Our results have expanded the spectrum of TRAPPC2 mutations and is helpful for presymptomatic and prenatal diagnoses of this disease.

Early prenatal diagnosis for a family affected with X-linked spondyloepiphyseal dysplasia tarda family

X-linked spondyloepiphyseal dysplasia tarda (SEDL) is a rare osteochondrodysplasia caused by mutations of SEDL gene, which usually onset in late childhood without systemic complications. In this study, we have provided prenatal diagnosis for an affected family with a combined strategy including direct sequencing, fetal-sex identification and microsatellite linkage analysis. Two amniotic fluid samples from carrier gravida and 7 blood samples from individuals in this SEDL pedigree were obtained. Genomic DNA was extracted from the samples using standard phenol-chloroform method. SRY and AMEL genes were employed to assess fetal sex. Microsatellite DXS16 was genotyped for linkage analysis. A pathogenic mutation of the SEDL gene was identified by bi-directionally direct sequencing of the third exon as well as its exon/intron boundaries. Two male fetuses were confirmed by fetal-sex assessment. The mutation of the SEDL gene was identified as a nucleotide substitution of the splice acceptor site in intron 2, IVS2-2A>C. DNA sequencing indicated that one fetus is hemizygote carrying the mutation, whilst another is not a carrier. Linkage analysis was identical with the sequencing results. Follow-up also confirmed the result of prenatal diagnosis. Fetal-sex assessment combined with microsatellite linkage analysis and bi-directionally direct sequencing is a more accurate and ready strategy for prenatal diagnosis of families affected with SEDL.

Prenatal diagnosis of a case with X-linked spondyloepiphyseal dysplasia tarda

To analyze TRAPPC2 gene mutation in a family with X-linked spondyloepiphyseal dysplasia tarda and to provide genetic counseling and prenatal diagnosis. All of 4 exons of the TRAPPC2 gene and their flanking sequences in the proband and her father were analyzed with polymerase chain reaction and direct DNA sequencing. Genomic DNA of the probands' fetus was extracted from amniotic fluid sampled at 18th gestational week. Gender of the fetus was determined by the presence of SRY gene. The sequence of fetal TRAPPC2 gene was also analyzed. A c.209G>A mutation was identified in exon 4 of the TRAPPC2 gene in the proband and her father. The fetus of was determined to be a male and also have carried the c.209G>A mutation. A c.209G>A mutation of TRAPPC2 exon 4 probably underlies the clinical manifestations in this family. The proband is a carrier, and her fetus is a male carrying the same mutation. Prenatal diagnosis is an effective method for the prevention of the disease.

X-Linked Spondyloepiphyseal Dysplasia Tarda: Identification of a TRAPPC2 Mutation in a Korean Pedigree

Spondyloepiphyseal dysplasia (SED) comprises a heterogeneous group of skeletal dysplasias that primarily affect the epiphyses and vertebral bodies. Patients affected by SED usually exhibit short stature and experience early development of degenerative osteoarthritis. SED is subdivided into congenita and tarda forms according to the age at onset and clinical severity, and further subdivided into genetically different forms according to the mode of inheritance and the gene involved. We report a 14-yr-old Korean male who presented with a disproportionately short stature and a short trunk. A pedigree analysis of 3 generations with 6 affected persons revealed an X-linked recessive mode of inheritance. Mutation analysis of the TRAPPC2 (previously called SEDL) gene, the only gene associated with X-linked spondyloepiphyseal dysplasia tarda (X-linked SEDT; MIM 313400), was performed, and a splice-donor site mutation in intron 3 of the TRAPPC2 gene (c.93+5G>A) was identified in the proband and in his unaffected mother (a heterozygote). This mutation is one of the 2 most frequent mutations reported in the medical literature, and is known to result in exon 3 skipping. This is the first report of a genetically confirmed X-linked SEDT case in Korea and highlights the importance of recognizing the mode of inheritance in the diagnosis of X-linked SEDT.

Incidental Finding of Tc-99m MDP Bone Scintigraphy in a Case of X-Linked Spondyloepiphyseal Dysplasia Tarda

A 26-year-old male presented with a history of backache and multijoint pain over the preceding 15 years. Bone scintigraphy demonstrated a short spine in addition to abnormally increased activity in multiple joints. The patient was eventually diagnosed to have X-linked spondyloepiphyseal dysplasia tarda.

The adaptor function of TRAPPC2 in mammalian TRAPPs explains TRAPPC2-associated SEDT and TRAPPC9-associated congenital intellectual disability.

BackgroundThe TRAPP (Transport protein particle) complex is a conserved protein complex functioning at various steps in vesicle transport. Although yeast has three functionally and structurally distinct forms, TRAPPI, II and III, emerging evidence suggests that mammalian TRAPP complex may be different. Mutations in the TRAPP complex subunit 2 (TRAPPC2) cause X-linked spondyloepiphyseal dysplasia tarda, while mutations in the TRAPP complex subunit 9 (TRAPPC9) cause postnatal mental retardation with microcephaly. The structural interplay between these subunits found in mammalian equivalent of TRAPPI and those specific to TRAPPII and TRAPPIII remains largely unknown and we undertook the present study to examine the interaction between these subunits. Here, we reveal that the mammalian equivalent of the TRAPPII complex is structurally distinct from the yeast counterpart thus leading to insight into mechanism of disease.Principal FindingsWe analyzed how TRAPPII- or TRAPPIII- specific subunits interact with the six-subunit core complex of TRAPP by co-immunoprecipitation in mammalian cells. TRAPPC2 binds to TRAPPII-specific subunit TRAPPC9, which in turn binds to TRAPPC10. Unexpectedly, TRAPPC2 can also bind to the putative TRAPPIII-specific subunit, TRAPPC8. Endogenous TRAPPC9-positive TRAPPII complex does not contain TRAPPC8, suggesting that TRAPPC2 binds to either TRAPPC9 or TRAPPC8 during the formation of the mammalian equivalents of TRAPPII or TRAPPIII, respectively. Therefore, TRAPPC2 serves as an adaptor for the formation of these complexes. A disease-causing mutation of TRAPPC2, D47Y, failed to interact with either TRAPPC9 or TRAPPC8, suggesting that aspartate 47 in TRAPPC2 is at or near the site of interaction with TRAPPC9 or TRAPPC8, mediating the formation of TRAPPII and/or TRAPPIII. Furthermore, disease-causing deletional mutants of TRAPPC9 all failed to interact with TRAPPC2 and TRAPPC10.ConclusionsTRAPPC2 serves as an adaptor for the formation of TRAPPII or TRAPPIII in mammalian cells. The mammalian equivalent of TRAPPII is likely different from the yeast TRAPPII structurally.

SEDLIN forms homodimers: characterisation of SEDLIN mutations and their interactions with transcription factors MBP1, PITX1 and SF1.

BackgroundSEDLIN, a 140 amino acid subunit of the Transport Protein Particle (TRAPP) complex, is ubiquitously expressed and interacts with the transcription factors c-myc promoter-binding protein 1 (MBP1), pituitary homeobox 1 (PITX1) and steroidogenic factor 1 (SF1). SEDLIN mutations cause X-linked spondyloepiphyseal dysplasia tarda (SEDT).Methodology/Principal FindingsWe investigated the effects of 4 missense (Asp47Tyr, Ser73Leu, Phe83Ser and Val130Asp) and the most C-terminal nonsense (Gln131Stop) SEDT-associated mutations on interactions with MBP1, PITX1 and SF1 by expression in COS7 cells. Wild-type SEDLIN was present in the cytoplasm and nucleus and interacted with MBP1, PITX1 and SF1; the SEDLIN mutations did not alter these subcellular localizations or the interactions. However, SEDLIN was found to homodimerize, and the formation of dimers between wild-type and mutant SEDLIN would mask a loss in these interactions. A mammalian SEDLIN null cell-line is not available, and the interactions between SEDLIN and the transcription factors were therefore investigated in yeast, which does not endogenously express SEDLIN. This revealed that all the SEDT mutations, except Asp47Tyr, lead to a loss of interaction with MBP1, PITX1 and SF1. Three-dimensional modelling studies of SEDLIN revealed that Asp47 resides on the surface whereas all the other mutant residues lie within the hydrophobic core of the protein, and hence are likely to affect the correct folding of SEDLIN and thereby disrupt protein-protein interactions.Conclusions/SignificanceOur studies demonstrate that SEDLIN is present in the nucleus, forms homodimers and that SEDT-associated mutations cause a loss of interaction with the transcription factors MBP1, PITX1 and SF1.

A novel insertion mutation in the SEDL gene results in X-linked spondyloepiphyseal dysplasia tarda in a large Chinese pedigree

Background Spondyloepiphyseal dysplasia tarda (SEDT) is an X-chromosome linked primary skeletal dysplasia characterized by a disproportionate short-trunked short stature, dysplasia of the large joints and flattened thoracic and lumber vertebral bodies. The objective of this study is to describe a large Chinese SEDT family with a milder phenotype and describe the molecular and clinical findings. Methods Eight affected males of the family were diagnosed with SEDT according to their clinical and radiological features. Direct DNA sequencing of the SEDL gene was performed. RT-PCR experiments on total RNA from blood lymphocytes were performed to confirm the defect on the SEDL gene. A short summary of all currently known SEDL gene mutations is presented. Results DNA sequencing revealed that all the affected males carried an insertion mutation (c.370-371insA) unreported previously, predicted to result in frameshifts and generate a premature stop codon (p.S124fsX127). The identical mutation was also observed in a 10-year old presymptomatic boy of the family. Eight female carriers had the typical sequencing chromatograms of heterozygotes. Conclusions Identification of the novel insertion mutation (c.370-371insA) in this SEDT family enables carrier detection and presymptomatic/prenatal diagnosis, but also the detailed molecular and clinical features will be useful for extending the evidence for genetic and phenotypic heterogeneity in SEDT.

A novel RNA-splicing mutation in TRAPPC2 gene causing X-linked spondyloepiphyseal dysplasia tarda in a large Chinese family

X-linked spondyloepiphyseal dysplasia tarda (SEDT; OMIM 313400) is a rare osteochondrodysplasia that occurs in affected individuals between 3 and 12 yr of age. Clinical features include short trunk, barrel-shaped chest and disproportionate short stature. Radiological abnormalities may become evident between 10 and 14 yr of age and include platyspondyly with hump-shaped central and posterior portions of the vertebrae, narrow disc spaces and moderate epiphyseal dysplasia of the long bones, which may be associated with osteoarthritis. Female heterozygous carriers are clinically and radiographically normal. SEDT is caused by mutations in the TRAPPC2 gene, (trafficking protein particle complex 2), which spans a genomic region of ∼20 kb in Xp22. In a large Chinese SEDT family, we screened all the six exons of the TRAPPC2 gene and identified a novel RNA-splicing mutation (IVS4+1A>G). We also demonstrated that the mutation induced splice pattern change from AT/AC to GT/AG. As a result, the first seven nucleotides of exon 5 were spliced out from the transcript. The prediction of the amino acid sequence showed that the seven nucleotides deletion of the transcript caused frame shift and led to premature translation termination, causing loss of two alpha helices. The results of our study expand the spectrum of the gene mutations associated with SEDT, and will help further to elucidate the role of this protein in the etiology of this form of osteochondrodysplasia. X-linked spondyloepiphyseal dysplasia tarda mutations in the TRAPPC2 gene previously identified as SEDL gene,

Noncanonical and canonical splice sites: a novel mutation at the rare noncanonical splice-donor cut site (IVS4+1A>G) of SEDL causes variable splicing isoforms in X-linked spondyloepiphyseal dysplasia tarda

X-linked spondyloepiphyseal dysplasia tarda can be caused by mutations in the SEDL gene. This study describes an interesting novel mutation (IVS4+1A>G) located exactly at the rare noncanonical AT-AC consensus splicing donor point of SEDL, which regained the canonical GT-AG consensus splicing junction in addition to several other rarer noncanonical splice patterns. The mutation activated several cryptic splice sites and generated the production of seven erroneous splicing isoforms, which we confirmed by sequencing of RT-PCR products and resequencing of cDNA clones. All the practical splice donors/acceptors were further assessed using FSPLICE 1.0 and SPL(M) Platforms to predict potential splice sites in genomic DNA. Subsequently, the expression levels of SEDL among the affected patients, carriers and controls were estimated using real-time quantitative PCR. Expression analyses showed that the expression levels of SEDL in both patients and carriers were decreased. Taken together, these results illustrated how disruption of the AT donor site in a rare AT-AC intron, leading to a canonical GT donor site, resulted in a multitude of aberrant transcripts, thus impairing exon definition. The unexpected splicing patterns resulting from the special mutation provide additional challenges and opportunities for understanding splicing mechanisms and specificity.

X‐linked spondylo‐epiphyseal dysplasia tarda in the Danish‐Swedish farm hound

In two litters from the same parents, three out of four males had an abnormally short leg and body length. Affected dogs showed signs of pain when moving, which could be eliminated by analgesia. On radiography, these animals had widened, radiolucent, irregularly bordered intervertebral disc spaces. When examined at seven months of age, the epiphyses appeared widened and irregular in shape and outline. General bone opacity in the vertebral column was lower in the affected male dogs than in the normal littermate. The affected dogs developed spondylosis and arthrosis of the larger limb joints. All affected dogs were euthanased on humane grounds, the eldest at the age of two years nine months. Based on the clinical and radiographic evidence, the condition seen in the male dogs described here resembles X-linked spondylo-epiphyseal dysplasia tarda caused by a collagenopathy due to malformation of COL2A1 as seen in human beings.

X-linked spondyloepiphyseal dysplasia tarda: Novel and recurrent mutations in 13 European families.

X-linked spondyloepiphyseal dysplasia tarda is a skeletal dysplasia mainly affecting the vertebrae and epiphyses and commonly associated with the early development of degenerative joint disease. Radiographically the disorder is characterized by a typical hump-shaped deformity of the vertebral bodies. SEDT is caused by mutations in SEDL located on Xp22.12-p22.31. To further elucidate the spectrum of underlying variations we performed a screening of all 6 exons of SEDL within 13 European SEDT families and identified 6 new (c.99delC, c.183_184delGA, c.236-5_236-8delATTA, c.325delT, c.345_346delTG, c.94-?_423+?del) and 9 previously reported mutations (c.1-?_93+?del, c.93+5G>A, c.157_158delAT, c.210G>A, c.236-9_236-12delTTAA, c.267_275delAAGAC, c.324-4_324-10delTCTTTCCinsAA). The recurrent splice site alteration c.93+5G>A (formerly described as IVS3+5G>A) was detected in 3 unrelated families. Two patients were carrying 2 changes in the allele. In one case, a novel variation in exon 4 (c.99delC) was associated with several nucleotide deletions in intron 4 (c.236-5_236-8delATTA), and in the second case we identified a previously reported transition c.210G>A and a novel deletion in exon 6 (c.325delT). All sequence variations identified are either deletions of complete exons or predicted to result in a premature stop codon or to lead into splicing defects and are associated with a loss of considerable parts of the sedlin protein.

Human wild-type SEDL protein functionally complements yeast Trs20p but some naturally occurring SEDL mutants do not

X-linked spondyloepiphyseal dysplasia tarda (SEDT, or SEDL) is a primary skeletal dysplasia affecting mostly spinal vertebral bodies and epiphyses. Previously, we have identified the SEDL gene and determined the spectrum of 21 different SEDL causing mutations. The SEDL gene is a highly conserved gene with an as yet unknown function. The yeast SEDL protein ortholog, Trs20p, has been isolated as a member of a large multi-protein complex (∼10 proteins) called transport protein particle (TRAPP), which is involved in endoplasmic reticulum (ER)-to-Golgi transport. While the SEDL gene mutations cause a tissue-specific (epiphyses) and relatively mild phenotype, the Trs20p function is essential for the yeast cell. We now provide evidence that recombinant human SEDL protein is able to functionally complement the Saccharomyces cerevisiae TRS20 (TRAPP subunit 20 gene) knockout mutant. This finding strongly supports the speculated conserved nature of the SEDL/Trs20p function. To shed further light on the SEDL/Trs20p protein function, five different naturally occurring SEDL gene mutations have been tested in complementation studies. While two truncation mutations (157delAT and C271T) and one missense mutation (G139T) were unable to rescue the trs20Δ lethal phenotype, two other missense mutations (C218T and T389A) did complement trs20Δ. Interestingly, there is no obvious correlation between the nature and position of the SEDL mutation and the clinical severity of the disorder among the human SEDL patients. Although the identification of complementing SEDL gene mutations may suggest the existence of subtle phenotypic differences among SEDL patients, it might also point towards the identification of SEDL protein residues/domains specific for normal, vertebrate bone growth.

X-linked spondyloepiphyseal dysplasia tarda: a novel SEDL mutation in a Jewish Ashkenazi family and clinical intervention considerations.

X-linked spondyloepiphyseal dysplasia tarda (SEDT; MIM 313400) is a late onset progressive skeletal disorder, which manifests in childhood and is characterized by disproportionate short stature with a short trunk, barrel chest and absence of systemic complications. We found a single-nucleotide deletion in position 613 of the SEDL gene in two brothers of Jewish-Ashkenazi ancestry afflicted with the disease. This is the first description of SEDL mutations in a Jewish family. Following this finding, an eight-month old second cousin of the brothers, who had yet no clinical or radiological signs of the disease, was found to carry the deletion. Another relative, 24-years old, carrying the same mutation was 1.61 m tall and had only minimal signs of the disease. These findings raise the dilemma of pre-natal counseling in SEDL and the need for exploring means of early intervention in pre-symptomatic cases.

A Novel Nonsense Mutation of the Sedlin Gene in a Family with Spondyloepiphyseal Dysplasia Tarda

We report a new nonsense mutation in the human sedlin (SEDL) gene in a family with X-linked spondyloepiphyseal dysplasia tarda. A substitution of cytosine for adenine at nucleotide position 329 causing a nonsense mutation (S110X) in exon 6 was identified in the affected patient in the family.