WISP3 mutational analysis in Indian patients diagnosed with progressive pseudorheumatoid dysplasia and report of a novel mutation at p.Y198

Clinical and molecular characterization in a cohort of patients with progressive pseudorheumatoid dysplasia

Progressive pseudorheumatoid dysplasia (PPRD), a rare autosomal recessive syndrome, is a type of skeletal dysplasia associated with pain, stiffness, swelling of multiple joints, and the absence of destructive changes. PPRD occurs due to loss of function pathogenic variants in WISP3 (CCN6) gene, located on chromosome 6q22. In this study, 23 unrelated Egyptian PPRD patients were clinically diagnosed based on medical history, physical and radiological examinations, and laboratory investigations. Sequencing of the whole WISP3 (CCN6) exons and introns boundaries was carried out for all patients. A total of 11 different sequence variations were identified in the WISP3 (CCN6) gene, five of them were new pathogenic variants: the NM_003880.3: c.80T>A (p.L27*), c.161delG (p.C54fs*12), c.737T>C (p.Leu246Pro), c.347-1G>A (IVS3-1G>A), and c.376C>T (p.Q126*). The results of this study expand the spectrum of WISP3 (CCN6) pathogenic variants associated with PPRD. Clinical and genetic analysis is important for proper genetic counseling to curb this rare disorder in the families.

Exploring and expanding the phenotype and genotype diversity in seven Chinese families with spondylo-epi-metaphyseal dysplasia

Spondylo-epi-metaphyseal dysplasia (SEMD) is a heterogeneous group of disorders with different modes of inheritance and is characterized by disproportionate or proportionate short stature. To date, more than 30 disease-causing genes have been identified, and different types of SEMD exhibit greatly overlapping clinical features, which usually complicate the diagnosis. This study was performed to expand the clinical and molecular spectrum of SEMD among Chinese subjects and to explore their potential phenotype–genotype relations. We enrolled seven families including 11 affected patients with SEMD, and their clinical, radiographic, and genetic data were carefully analyzed. All the seven probands showed different degrees of short stature, and each of them exhibited additional specific skeletal manifestations; four probands had extraosseous manifestations. X-rays of the seven probands showed common features of SEMD, including vertebral deformities, irregular shape of the epiphysis, and disorganization of the metaphysis. Seven variants were identified in TRPV4 (c.694C> T, p.Arg232Cys), COL2A1 (c.654 + 1G > C; c.3266_3268del, p.Gly1089del), CCN6 (c.396 T> G, p.Cys132Trp; c.721 T>C, p.Cys241Arg), SBDS (c.258 + 2T> C), and ACAN (c.1508C> A, p.Thr503Lys) genes, and two of them were novel. Two families with TRPV4 variants showed considerable intrafamily and interfamily heterogeneities. In addition, we reported one case of SEMD with a severe phenotype caused by ACAN gene mutation. Our study expands the phenotype and genetic spectrum of SEMD and provides evidence for the phenotype–genotype relations, aiding future molecular and clinical diagnosis as well as procreative management of SEMD.

Specific early signs and long-term follow-up findings of Progressive Pseudorheumatoid Dysplasia (PPRD) in the Turkish cohort

OBJECTIVES

Progressive pseudorheumatoid dysplasia (PPRD) is a spondyloepiphyseal dysplasia caused by biallelic variants in CCN6. This study aimed to describe the early signs and follow-up findings in forty-four Turkish PPRD patients.

METHODS

The patients with progressive stiffness of multiple joints, characteristic wide metaphysis of interphalangeal (IP) joints, and platyspondyly were clinically diagnosed with PPRD. Fifteen patients who had first symptoms under 3 years of age were grouped as early-onset, while others were grouped as classical. CCN6 sequencing was performed in 43 patients.

RESULTS

Thirteen pathogenic/likely pathogenic variants were identified, five were novel. c.156C>A(p.Cys52*) variant was found in 53.3% of the families. The initial symptom in the early-onset group was genu varum deformity, while it was widening of IP joints in the classical group. The median age of onset of symptoms and of diagnosis was 4 and 9.7 years, respectively. The mean follow-up duration was 5.6 years. The median age of onset of IP, elbow, knee, and hip stiffness, which became progressive with growth was 5, 9, 9, and 12.2 years, respectively. Waddling gait occurred in 97.7% of the patients. 47.7% lost independent walking ability at the median age of 12 years. In the early-onset group, waddling gait occurred earlier than in classical group (p< 0.001). Two patients had atypical presentation with late-onset and mild or lack of IP involvement.

CONCLUSION

We observed that genu varum deformity before the age of 3 years was an early sign for PPRD and almost half of the patients lost walking ability at the median age of 12 years.

Multi-scale mechanical investigation of articular cartilage suffered progressive pseudorheumatoid dysplasia

BACKGROUND

Progressive pseudorheumatoid dysplasia is a rare skeletal dysplasia mainly caused by abnormal autosomal recessive inheritance. Although the main function of cartilage is mechanical support and the characteristics of this disease is the degradation of AC, previous studies on it had been mainly focused on clinical and genetic aspects and the mechanical behavior of the cartilage affected by PPRD is still ambiguous. In this study, we investigate the mechanics and structure of the cartilage suffered disease at multi-scale, from individual chondrocytes to the bulk-scale tissue.

METHODS

Depth-sensing indenter were employed to investigate the mechanics of cartilage; we performed atomic force microscope nanoindentation to investigate the cell mechanics and scanning electron microscopy were used to explore the structure feature and chemical composition.

FINDINGS

The elastic modulus of chondrocytes harvested from cartilage suffered from progressive pseudorheumatoid dysplasia is significantly higher than from normal cartilage, same trend were also found in tissue level. Moreover, denser collagen meshwork and matrix calcification were also observed.

INTERPRETATION

The elastic modulus of cartilage should closely related to its denser structure and the calcification, and may potentially be an indicator for clinical diagnosis. The stiffening of chondrocytes during PPRD progression should play a rather important role in its pathogenesis.

CCN6 mutation detection in Chinese patients with progressive pseudo-rheumatoid dysplasia and identification of four novel mutations

Background

No formal diagnostic criteria for progressive pseudo‐rheumatoid dysplasia (PPD) are available because of insufficient clinical data, which results in that PPD is often misdiagnosed with other diseases. Whole exome sequencing (WES) and Sanger sequencing were employed to reveal the novel mutations on CCN6 of five patients with PPD from China in order to increase the clinical data of PPD.

Methods

Four suspected PPD pedigrees containing five patients in total were collected from 1998 to 2018 in our medical center. The phenotypes of each suspected PPD case were recorded in detail, and peripheral blood samples were collected for subsequent sequencing. Genomic DNA was extracted from peripheral blood samples, and Agilent liquid phase chip capture system was utilized for efficient enrichment of whole exome region DNA. After acquiring raw sequenced reads of whole exome region, bioinformatics analysis was completed in conjunction with reference or genome sequence (GRCh37/hg19). Sanger sequencing was performed to identify the results of WES.

Results

In total, four novel PPD‐related mutation sites in CCN6 gene were identified including (CCN6):c.643 + 2T>C, (CCN6):c.1064_1065dupGT(p.Gln356ValfsTer33), (CCN6):c.1064G > A), and exon4:c.670dupA:p.W223fs.

Conclusion

Our findings increase the clinical data of PPD including the CCN6 mutation spectrum, the clinical symptoms and signs. Moreover, the study highlights the utility of WES in reaching definitive diagnoses for PPD.

Skeletal phenotype/genotype in progressive pseudorheumatoid chondrodysplasia

BACKGROUND

Axial and extra-axial deceleration in function and progressive joint pain with subsequent development of antalgic gait associated with swellings, and stiffness of the joints with loss of the physiological spine biomechanics were the natural history in this group of patients. Clinical and radiological phenotypes have been analysed carefully to further understand the aetiology behind.

METHODS

Seven patients (three children around the age of 9-11 and one child of 17 years old). Three adults aging 25, 30, 33 and 40 years old were seen and examined. The paediatric group of patients were initially diagnosed with myopathy followed later by juvenile rheumatoid arthritis in other institutions. Clinical and imaging documentation were collected in our departments, followed by mutation screening, was carried out by bidirectional sequencing of the WISP3 gene.

RESULTS

Clinical and radiological phenotypic studies confirmed the diagnosis of progressive pseudorheumatoid chondrodysplasia. A constellation of abnormalities such as early senile hyperostosis of the spine (Forestier disease), osteoarthritis of the hips showed progressive diminution and irregularities of the hip joint spaces associated with progressive capital femoral epiphyseal dysplasia and coxa vara have been encountered. Loss-of-function homozygous mutations (c.667T>G, p.Cys223Gly) and (c.170C>A, p.Ser57*) in the WISP3 gene were identified in our patients.

CONCLUSION

The definite diagnosis was not defined via vigorous myopathic and rheumatologic investigations. Detailed clinical examination and skeletal survey, followed by genotypic confirmation, were our fundamental pointers to rule out the false diagnosis of juvenile rheumatoid arthritis and rheumatoid polyarthritis in the adult group of patients. We wish to stress that the clinical/radiological phenotype is the baseline tool to establish a definite diagnosis and to guide the geneticist toward proper genotype.Key Points•Joint pain and difficulties in walking/climbing the stairs are characteristic features encountered in early childhood. False diagnosis of juvenile rheumatoid arthritis can be made at this point.•False positive-like muscular wasting resembling myopathy results in ensuing vigorous troublesome investigations.•Flattened vertebral bodies associated with defective ossification of the anterior end plates are characteristic features of progressive pseudorheumatoid chondrodysplasia.•Joint expansions, which are usually accompanied by narrowing of the articular ends of the appendicular skeletal system, show a clear radiological phenotype of pseudorheumatoid chondrodysplasia.

Progressive pseudorheumatoid dysplasia: a rare childhood disease

Progressive pseudorheumatoid dysplasia (PPRD) is a genetic bone disorder characterised by the progressive degeneration of articular cartilage that leads to pain, stiffness and joint enlargement. As PPRD is a rare disease, available literature is mainly represented by single case reports and only a few larger case series. Our aim is to review the literature concerning clinical, laboratory and radiological features of PPRD. PPRD is due to a mutation in Wnt1-inducible signalling protein 3 (WISP3) gene, which encodes a signalling factor involved in cartilage homeostasis. The disease onset in childhood and skeletal changes progresses over time leading to significant disability. PPRD is a rare condition that should be suspected if a child develops symmetrical polyarticular involvement without systemic inflammation, knobbly interphalangeal joints of the hands, and gait abnormalities. A full skeletal survey, or at least a lateral radiograph of the spine, can direct towards a correct diagnosis that can be confirmed molecularly. More than 70 WISP3 mutations have so far been reported. Genetic testing should start with the study of genomic DNA extracted from blood leucocytes, but intronic mutations in WISP3 causing splicing aberrations can only be detected by analysing WISP3 mRNA, which can be extracted from cultured skin fibroblasts. A skin biopsy is, therefore, indicated in patients with typical PPRD findings and negative mutation screening of genomic DNA.

Progressive pseudorheumatoid dysplasia with new-found gene mutation of Wntl inducible signaling pathway protein 3

BACKGROUND

As one kind of osteochondrodysplasia, progressive pseudorheumatoid dysplasia (PPD) is also known as spondyloepiphyseal dysplasia tarda with progressive arthropathy or arthropathy progressive pseudorheumatoid of childhood. PPD is a very rare disease, especially in China, and has an estimated prevalence of 1/1000000 due to lacking definite prevalence survey. It is an autosomal recessive disorder caused by gene mutation of Wntl inducible signaling pathway protein 3 (WISP3). Its basic pathological change is persistent degeneration and loss of articular cartilage in multiple joints. Its clinical appearances include bone enlargement, platyspondyly, irregular endplate, secondary osteoarthritis, extensive osteoporosis, joint rigidity and function loss. Clinical diagnosis of PPD is made based on clinical appearance and imaging examinations, whereas its definite diagnosis depends on gene sequencing. PPD has no severe effect on life span, but causes high disability rate and very poor prognosis. There are only case reports with limited information in China.

CASE PRESENTATION

One female patient was diagnosed as PPD and secondary osteoarthritis. She had typical clinical appearance and imaging examinations, and received individualized therapeutic regimens. She had a gene mutation (c.72delT, p.T24TfsX4) of WISP3. This gene mutation has not been reported by previous literatures and included in Single Nucleotide Polymorphism Database.

CONCLUSIONS

As the first time, this paper reported a patient with PPD caused by new-found gene mutation (c.72delT, p.T24TfsX4) of WISP3.

WISP3 mutation associated with pseudorheumatoid dysplasia

Progressive pseudorheumatoid dysplasia (PPD) is a skeletal dysplasia characterized by predominant involvement of articular cartilage with progressive joint stiffness. Here we report genetic characterization of a consanguineous family segregating an uncharacterized from of skeletal dysplasia. Whole-exome sequencing of four affected siblings and their parents identified a loss-of-function homozygous mutation in the WISP3 gene, leading to diagnosis of PPD in the affected individuals. The identified variant (Chr6: 112382301; WISP3:c.156C>A p.Cys52*) is rare and predicted to cause premature termination of the WISP3 protein.