The diagnostic challenge of progressive pseudorheumatoid dysplasia (PPRD): A review of clinical features, radiographic features, and WISP3 mutations in 63 affected individuals

Progressive Pseudorheumatoid Dysplasia of Childhood (PPRD)-A Case Series with Recurrent c.740_741del Variant

Progressive pseudorheumatoid dysplasia (PPRD) is an autosomal recessive arthropathy, affecting school-aged children. It is characterized by progressive degeneration of the articular cartilage. The majority of the pathogenic variations are found in exon 2, exon 4, and exon 5 of the putative gene, CCN6 (WISP3). Three unrelated individuals with clinical diagnosis of PPD were included in this study. Detailed clinicoradiological evaluation was attempted with brief literature review. Exome sequencing was performed in all three cases. All the pathogenic variations detected in our cohort were located in exons 2 and 4 of WISP3 gene. Though the clinicoradiological features are already well described, this study in north India highlights the occurrence of a recurring pathogenic variant. The c.740_741del variant was a recurrent pathogenic variant seen in all three patients in this cohort. This may be a common pathogenic variant in the North Indian population; however, a larger cohort needs to be studied before drawing final conclusions. A proper molecular diagnosis is a must to end the diagnostic odyssey, safeguarding patients with PPRD from unnecessary use of drugs like corticosteroids.

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.

Case 316: Progressive Pseudorheumatoid Dysplasia

HISTORY

A 10-year-old North Indian boy presented with swelling of multiple joints in his hands for the past 3 years. This swelling involved the small joints of his hands and some restriction of joint movement, without any associated tenderness or morning stiffness. No other joints were symptomatically involved. Prior to visiting our hospital, he had received disease-modifying antirheumatoid drugs for suspected juvenile idiopathic arthritis, without any clinical benefit. On examination, the metacarpophalangeal and interphalangeal joints were nontender but had swelling and flexion deformities. He also had a short stature (below the third centile) for his age. Inflammatory markers, including erythrocyte sedimentation rate (7 mm per hour; normal range, 0-22 mm per hour) and C-reactive protein level (1.5 mg/L; normal level, <10 mg/L), were normal, and the rheumatoid factor test result was negative. A skeletal survey of the patient was performed.

Unique mutation spectrum of progressive pseudorheumatoid dysplasia in the Chinese population: a retrospective genotype-phenotype analysis of 105 patients

BACKGROUND

Progressive pseudorheumatoid dysplasia (PPRD) is a rare genetic disease with autosomal recessive inheritance. There was a lack of genotype-phenotype correlation data from the Chinese population. This study aimed to identify the genotype and phenotype characteristics of Chinese PPRD patients and to conduct a genotype-phenotype analysis of Chinese PPRD patients.

METHODS

Genetic analysis was performed for suspected PPRD patients from Peking Union Medical College Hospital. Medical records were collected from the electronic medical record system and patient-held portable health records. Published Chinese PPRD cases were gathered from both international and Chinese local databases. We collected demographic information, genetic variants, clinical manifestations, and imaging characteristics for further analysis.

RESULTS

We included 105 Chinese PPRD patients in the current study. Thirty-three variants, including nine novels and five hotspot variants, were identified, with 26/33 (79%) variants exclusively seen in the Chinese population. Chinese PPRD patients share a phenotype similar to that in international reports. Joint involvement may progress with age (R2 = 0.2541). Long bone shortening and severe deformities occur in three patients with biallelic null variants, of which at least one variant is located in exon 2. Among hotspot variants, c.624dupA (p.C209Mfs*21) were associated with later onset and more involved joints. Elbow joints were more likely to be affected in patients carrying c.624dupA (p.C209Mfs*21) and c.866dupA (p.S209Efs*13). Shoulder joints are more likely to be involved in patients with biallelic null variants (P = 0.027).

CONCLUSIONS

Chinese PPRD patients share a unique mutation spectrum. Among the five hotspot variants, c.624dupA is associated with later onset of disease, more extensive joint involvement, and a tendency to affect elbow joints. Biallelic null variants with at least one variant in exon 2 could be a likely cause of long bone shortening and severe deformities.

CCN6 influences transcription and controls mitochondrial mass and muscle organization

Mutations in Cellular Communication Network Factor 6 (CCN6) are linked to the debilitating musculoskeletal disease Progressive Pseudo Rheumatoid Dysplasia (PPRD), which disrupts mobility. Yet, much remains unknown about CCN6 function at the molecular level. In this study, we revealed a new function of CCN6 in transcriptional regulation. We demonstrated that CCN6 localizes to chromatin and associates with RNA Polymerase II in human chondrocyte lines. Using zebrafish as a model organism we validated the nuclear presence of CCN6 and its association with RNA Polymerase II in different developmental stages from 10 hpf embryo to adult fish muscle. In concurrence with these findings, we confirmed the requirement of CCN6 in the transcription of several genes encoding mitochondrial electron transport complex proteins in the zebrafish, both in the embryonic stages and in the adult muscle. Reduction in the expression of these genes upon morpholino-mediated knockdown of CCN6 protein expression led to reduced mitochondrial mass, which correlated with defective myotome organization during zebrafish muscle development. Overall, this study suggests that the developmental musculoskeletal abnormalities linked with PPRD could be contributed at least partly by impaired expression of genes encoding mitochondrial electron transport complexes due to defects in CCN6 associated transcriptional regulation.

A Chinese case of CHST3-related skeletal dysplasia and a systematic review

PURPOSE

We reported a case with carbohydrate sulfotransferase 3 (CHST3) spondyloepiphyseal dysplasia and made a systematic review of all previously reported cases.

METHODS

A 14.8-year-old boy underwent clinical, radiological, and genetic evaluations. The patients and five age-matched healthy boys accepted high-resolution peripheral quantitative computed tomography evaluation. All CHST3-related skeletal dysplasia cases from PubMed and Embase were collected and summarized. The genotype-phenotype correlation was analyzed.

RESULTS

The proband complained of aggravated joint pain and had a compression fracture of L2 during his second decade. Physical examination showed a height Z score of -4.94, short limbs, and restricted movement of the elbows and knees. X-rays showed carpal epiphyseal dysplasia, enlargement of elbow and knee joints, and subluxation of the left hip. Echocardiography showed abnormal cardiac valves. Compared with the norm, his total and trabecular volumetric bone mineral density (BMD), and the microarchitecture of the trabecular bone had trends to be worse at the distal radius and tibia. Two novel missense variants of c.1343T>G and c.761C>G in CHST3 were inherited from his father and mother, respectively. In the systematic review, short stature, limited joint extension, joint pain, and joint dislocation were the most common characteristics of this disorder. Height Z score and the proportion of hearing impairment had no significant differences between the missense and nonmissense mutations groups.

CONCLUSION

Progressive joint pain and movement restriction are the main characteristics of CHST3-related skeletal dysplasia. BMD and bone microarchitecture of this disorder needs further exploration. There is no apparent genotype-phenotype correlation in this disorder.

Dry synovitis, a rare entity distinct from juvenile idiopathic arthritis

BACKGROUND

Dry synovitis (DS) is a rare entity as only a few cases have been reported to date. We describe the clinical features, radiological manifestations and course of DS in comparison with rheumatoid factor negative polyarticular juvenile idiopathic arthritis (RFneg-polyJIA).

METHODS

We performed a multicenter retrospective collection of data of DS patients who presented with progressive joint limitations without palpable synovitis, absence of elevated acute phase reactants, negative ANA and RF, and imaging showing joint and/or osteochondral involvement. For comparative purposes, we included a cohort of RF neg-polyJIA patients.

RESULTS

Twelve DS patients, 8F/4 M, with mean age at onset of 6.1 years, were included. Presenting signs comprised delayed motor development, functional limitations and/or progressive stiffness. Clinical examination showed symmetric polyarticular involvement with variable muscular atrophy. MRI showed mild, diffuse synovial involvement, without effusion. With time, signs of progressive osteochondral damage became evident, despite treatment. All patients were treated with low-dose corticosteroids and methotrexate. Anti-TNF agents were prescribed in five. The response was variable with limited joint mobility in 11/12, and need of joint replacement in 2. In comparison with a cohort of RFneg-polyJIA, DS patients presented higher number of joint involved (p = 0.0001) and contractures (p = 0.0001), less swelling (p = 0.0001) and prolonged diagnostic delay (p = 0.0001).

CONCLUSION

DS represents a unique juvenile-onset arthropathy, distinct from polyarticular JIA. Awareness among pediatricians is essential for early recognition and proper treatment. Further studies, including synovial pathology, immunology and genetics may contribute to a better understanding of this rare disorder of childhood.

Gait Alterations in Two Young Siblings with Progressive Pseudorheumatoid Dysplasia

Progressive pseudorheumatoid dysplasia (PPRD) is an autosomal recessive inherited skeletal dysplasia characterized by progressive non-inflammatory arthropathy affecting primarily the articular cartilage. Currently, little is known about the functional musculoskeletal aspects of these patients. In particular, an abnormal gait pattern has been described, without a clear hypothesis of the underlying causes in terms of muscular activity. This study presents the case of two siblings, 4 and 9 years old, a boy and a girl, respectively, suffering from PPRD at different stages of the disease. In addition to the clinical assessment, an instrumental gait analysis was performed. Swelling of the interphalangeal finger joints and fatigue were present in both cases. Gait abnormalities consisted of a relevant reduction in the ankle plantarflexion in the terminal phase of the gait cycle, associated with reduced gastrocnemius EMG activity and increased activity of the tibialis anterior, resulting in overloading at the initial peak of ground reaction forces. Gait anomalies observed were similar in both siblings with PPRD, although at different ages, and confirm walking patterns previously described in the literature. The calf muscle strength deficit and reduced activity during the stance phase of gait present in these two siblings indicate the typical absence of the propulsive phase. A stomping gait pattern, with the foot striking the ground hard on each step, was originally described. Further neurophysiological investigations are required to determine the origin of muscle weakness.

Multiple disc herniation in spondyloepiphyseal dysplasia tarda: A rare case report and review of the literature

BACKGROUND

Spondyloepiphyseal dysplasia tarda (SEDT) is a rare, hereditary, X-linked skeletal disorder. To our knowledge, there are few reports about orthopedic surgery in these patients. This is the first report on patients with SEDT undergoing spinal and fracture reduction surgery.

CASE PRESENTATION

A 31-year-old male patient who had been misdiagnosed with juvenile idiopathic arthritis (JIA) for 20 years and who had been treated with femoral shaft internal fixation for lower extremity fracture caused by minor trauma presented at hospital with stiffness and weakness in the lower extremities for the past two years. Radiographs showed bony dysplastic features of flattened vertebral bodies, Scheuermann-like changes in the spine, and osteoarthritis-like changes in the joints. Laboratory examination, including routine blood tests and rheumatism-related indicators showed negative results. Considering the history, radiology, and genetic findings, a diagnosis of spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA) was considered. Further neurological examination indicated that severe spinal cord compression was an important reason for the patient's inability to walk. Laminectomy, spinal canal decompression, internal fixation and fusion were performed. Clinical outcome was satisfactory at one-year follow-up. The lower-limb fatigue was relieved, the patient could walk independently, and his examination showed osseous fusion. The English database was searched and the literature was reviewed for the relevant keywords of "SEDT-PA".

CONCLUSIONS

Progress has been made in genetic research on SEDT; early diagnosis is particularly important, but the clinical diagnosis and treatment plans are still evaluated on a case-by-case basis. The best treatment for SEDT is to identify patients with progressive neurological and joint-mobility impairments and perform appropriate surgical intervention. Surgical intervention can improve neurological function and quality of life. However, surgery, as palliative care, does not alter the progression of the disease.

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&gt; T, p.Arg232Cys), COL2A1 (c.654 + 1G &gt; C; c.3266_3268del, p.Gly1089del), CCN6 (c.396 T&gt; G, p.Cys132Trp; c.721 T&gt;C, p.Cys241Arg), SBDS (c.258 + 2T&gt; C), and ACAN (c.1508C&gt; 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.

Analysis of Pathogenic Pseudoexons Reveals Novel Mechanisms Driving Cryptic Splicing

Understanding pre-mRNA splicing is crucial to accurately diagnosing and treating genetic diseases. However, mutations that alter splicing can exert highly diverse effects. Of all the known types of splicing mutations, perhaps the rarest and most difficult to predict are those that activate pseudoexons, sometimes also called cryptic exons. Unlike other splicing mutations that either destroy or redirect existing splice events, pseudoexon mutations appear to create entirely new exons within introns. Since exon definition in vertebrates requires coordinated arrangements of numerous RNA motifs, one might expect that pseudoexons would only arise when rearrangements of intronic DNA create novel exons by chance. Surprisingly, although such mutations do occur, a far more common cause of pseudoexons is deep-intronic single nucleotide variants, raising the question of why these latent exon-like tracts near the mutation sites have not already been purged from the genome by the evolutionary advantage of more efficient splicing. Possible answers may lie in deep intronic splicing processes such as recursive splicing or poison exon splicing. Because these processes utilize intronic motifs that benignly engage with the spliceosome, the regions involved may be more susceptible to exonization than other intronic regions would be. We speculated that a comprehensive study of reported pseudoexons might detect alignments with known deep intronic splice sites and could also permit the characterisation of novel pseudoexon categories. In this report, we present and analyse a catalogue of over 400 published pseudoexon splice events. In addition to confirming prior observations of the most common pseudoexon mutation types, the size of this catalogue also enabled us to suggest new categories for some of the rarer types of pseudoexon mutation. By comparing our catalogue against published datasets of non-canonical splice events, we also found that 15.7% of pseudoexons exhibit some splicing activity at one or both of their splice sites in non-mutant cells. Importantly, this included seven examples of experimentally confirmed recursive splice sites, confirming for the first time a long-suspected link between these two splicing phenomena. These findings have the potential to improve the fidelity of genetic diagnostics and reveal new targets for splice-modulating therapies.

Unilateral pachydermodactyly misdiagnosed as juvenile idiopathic arthritis: A case report

RATIONALE

Pachydermodactyly is a rare, benign disease that can manifest in healthy adolescent boys as painless, spindle-shaped, soft-tissue swelling of the proximal interphalangeal joints in the hand. It is usually bilateral, with symmetrical joint enlargement. There are relatively few documented cases of pachydermodactyly worldwide, signifying either a low incidence or lack of recognition by physicians; therefore, its diagnosis is challenging.

PATIENT CONCERNS

A 16-year-old boy with a 3-year history of painless unilateral swelling of the proximal interphalangeal joints of his left hand was misdiagnosed with juvenile idiopathic arthritis and was treated with oral methotrexate for 1 year. He had a history of frequent finger cracking.

DIAGNOSIS

He had normal levels of inflammatory markers, including erythrocyte sedimentation rate and C-reactive protein. His autoantibody profile results were normal, and radiography of his hands showed soft tissue swelling with no bone abnormalities. Therefore, the patient was diagnosed with Parkinson disease.

INTERVENTIONS

Methotrexate was discontinued, and a skin biopsy was performed, which revealed hyperkeratosis in the epidermis with thick collagenous fibers in the dermis. Therefore, the patient was informed of the benign nature of the disease and was advised to stop cracking his fingers.

OUTCOMES

After regular follow-up, there was no progression of the patient's symptoms, and repeated blood tests revealed normal results.

LESSONS

Pachydermodactyly should be considered in the differential diagnosis of painless swelling in adolescent men with normal blood testing. Early recognition of this rare benign condition helps physicians appropriately reassure the patient and his parents without exposing them to unnecessary therapy.

Inflammatory conditions of the pediatric hand and non-inflammatory mimics

Hand involvement can assume an outsized role in the perception and presentation of disease as a result of functional impairment, visual conspicuity and susceptibility to early structural damage. Rheumatologic referral for inflammatory conditions can be delayed because of assumptions of a traumatic, infectious or neoplastic etiology; conversely, initial rheumatologic evaluation might be pursued for many of the same non-inflammatory causes. This pictorial essay highlights inflammatory conditions affecting the pediatric hand, including juvenile idiopathic arthritis, infectious arthritis, systemic connective tissue disorders, and a variety of less common inflammatory diseases, as well as non-inflammatory congenital, vascular, neoplastic and metabolic differential considerations.

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.

Progressive pseudorheumatoid dysplasia misdiagnosed as juvenile idiopathic arthritis: a case report

BACKGROUND

Progressive pseudorheumatoid dysplasia is a rare, autosomal recessively inherited, noninflammatory musculoskeletal disorder caused by mutations occurring in the WNT1-inducible signaling pathway protein 3 gene. Joint cartilage is the primary site of involvement, leading to arthralgia, joint stiffness, contractures, enlargement of the epiphyses and metaphysis of the hand joints, spinal abnormalities, short stature, early osteoarthritis, and osteoporosis. Juvenile idiopathic arthritis is the most common chronic rheumatic disease in childhood and has unknown etiology. Clinical features of progressive pseudorheumatoid dysplasia resemble those of juvenile idiopathic arthritis. Patients with progressive pseudorheumatoid dysplasia are usually misdiagnosed as having juvenile idiopathic arthritis.

CASE PRESENTATION

A 13-year-old Yemeni female presented to the rheumatology clinic with a history of joint pains, bone pains, and bone deformity for 7 years. Weight and height were below the third percentiles. There was no tender swelling of metacarpophalangeal and interphalangeal joints, and she presented with scoliosis. Radiographs of the hands revealed the widening of the epiphyses. Progressive pseudorheumatoid dysplasia was suspected, and genetic testing for WNT1-inducible signaling pathway protein 1, 2, and 3 was requested with these findings. A homozygous, likely pathogenic variant was identified in the WNT1-inducible signaling pathway protein 3 gene, which confirmed our diagnosis.

CONCLUSION

Progressive pseudorheumatoid dysplasia is a rare form of spondyloepimetaphyseal dysplasia and is clinically misdiagnosed as juvenile idiopathic arthritis. It is crucial to consider progressive pseudorheumatoid dysplasia, especially in patients with standard inflammatory markers who are being followed up for juvenile idiopathic arthritis and not improving with antirheumatic intervention.

A retrospective study of nine patients with progressive pseudorheumatoid dysplasia: to explore early diagnosis and further treatment

OBJECTIVES

Most patients with progressive pseudorheumatoid dysplasia (PPRD) are initially misdiagnosed because of disease rarity and lack of awareness by most clinicians. The purpose of this study was to provide further early diagnostic options and potential treatment to patients with PPRD.

METHODS

A retrospective study was performed by collecting and organizing clinical manifestations, radiographic features, laboratory test results, genetic test outcome, treatment, and follow-up records of the patients with PPRD. Age of diagnosis and genotype-phenotype correlation were further analyzed.

RESULTS

Nine PPRD children with causative CCN6 mutation were included. There were 3 pairs of siblings and 1 patient from inbred family. Five patients were primarily misdiagnosed as juvenile idiopathic arthritis (JIA). The interval between onset of symptoms and definite diagnosis of 8 patients varied from 3.6 to 20 years. Symptoms at the onset included enlarged and stiff interphalangeal joints of the fingers, gait disturbance, or joint pain. Laboratory tests revealed normal range of inflammatory parameters. Radiographic findings disclosed different degrees of abnormal vertebral bodies and epiphyseal enlargement of the interphalangeal joints. After the treatment of calcitriol in 5 patients with low level 25-hydroxyvitamin D3 for around 1.25 years to 1.75 years, 2 patients kept stable, while 3 of them improved gradually.

CONCLUSIONS

Combining the patient's family history, clinical features, normal inflammatory markers, and the characteristic radiographic findings, the clinical diagnosis of PPRD for the patients could be obtained at very early stage of the disease. The patients with PPRD carrying c.624dupA variant in CCN6 may have delayed onset. Underlying vitamin D deficiency should be sought and corrected in patients with PPRD.

Progressive pseudorheumatoid dysplasia: A rare entity mimicking juvenile idiopathic arthritis

Progressive pseudorheumatoid dysplasia can be confused with juvenile idiopathic arthritis. Treatment is mainly symptomatic and the prescription of immunosupressive agents is unnecessary. Surgery may be indicated at advanced stages of the disease.

The combined prevalence of classified rare rheumatic diseases is almost double that of ankylosing spondylitis

BACKGROUND

Rare diseases (RDs) affect less than 5/10,000 people in Europe and fewer than 200,000 individuals in the United States. In rheumatology, RDs are heterogeneous and lack systemic classification. Clinical courses involve a variety of diverse symptoms, and patients may be misdiagnosed and not receive appropriate treatment. The objective of this study was to identify and classify some of the most important RDs in rheumatology. We also attempted to determine their combined prevalence to more precisely define this area of rheumatology and increase awareness of RDs in healthcare systems. We conducted a comprehensive literature search and analyzed each disease for the specified criteria, such as clinical symptoms, treatment regimens, prognoses, and point prevalences. If no epidemiological data were available, we estimated the prevalence as 1/1,000,000. The total point prevalence for all RDs in rheumatology was estimated as the sum of the individually determined prevalences.

RESULTS

A total of 76 syndromes and diseases were identified, including vasculitis/vasculopathy (n = 15), arthritis/arthropathy (n = 11), autoinflammatory syndromes (n = 11), myositis (n = 9), bone disorders (n = 11), connective tissue diseases (n = 8), overgrowth syndromes (n = 3), and others (n = 8). Out of the 76 diseases, 61 (80%) are classified as chronic, with a remitting-relapsing course in 27 cases (35%) upon adequate treatment. Another 34 (45%) diseases were predominantly progressive and difficult to control. Corticosteroids are a therapeutic option in 49 (64%) syndromes. Mortality is variable and could not be determined precisely. Epidemiological studies and prevalence data were available for 33 syndromes and diseases. For an additional eight diseases, only incidence data were accessible. The summed prevalence of all RDs was 28.8/10,000.

CONCLUSIONS

RDs in rheumatology are frequently chronic, progressive, and present variable symptoms. Treatment options are often restricted to corticosteroids, presumably because of the scarcity of randomized controlled trials. The estimated combined prevalence is significant and almost double that of ankylosing spondylitis (18/10,000). Thus, healthcare systems should assign RDs similar importance as any other common disease in rheumatology.

Progressive pseudorheumatoid dysplasia: a case series report

rogressive pseudorheumatoid dysplasia (PPRD) is a rare autosomal-recessive, noninflammatory arthropathy. Several cases have been reported worldwide; however, diagnosis remains challenging. Three unrelated children with PPRD were retrospectively studied. All three patients in this study were initially misdiagnosed. The misdiagnoses included juvenile rheumatoid arthritis, myodystrophy and idiopathic short stature. The time from the onset of symptoms to a definitive diagnosis was 3 to 8 years. Clinical signs and radiological phenotypes were analyzed carefully, and they were all consistent with the characteristics of PPRD and noninflammatory polyarticular enlargement. The small joints of both the hands and lower limbs are the most affected. The imaging findings of the patients were flat vertebrae with beak- or bullet-like changes in front of the cone and peripheral metaphysis widening. DNA samples obtained from the family were sequenced to identify the causal gene using whole-exome sequencing (WES). Four Wnt1-inducible signaling pathway protein 3 (WISP3) mutations were verified. c.271delC was not reported previously. The other three mutations, namely, c.136C>T (p. Gln46*), c.667T>G (p. Cys223Gly) and c.589+2T>C, were previously identified. All three patients had a long journey to diagnosis. Early genetic diagnosis can help prevent unnecessary treatments and procedures in patients. Growth hormone is not a good choice for treatment.

Ccn6 Is Required for Mitochondrial Integrity and Skeletal Muscle Function in Zebrafish

Mutations in the CCN6 (WISP3) gene are linked with a debilitating musculoskeletal disorder, termed progressive pseudorheumatoid dysplasia (PPRD). Yet, the functional significance of CCN6 in the musculoskeletal system remains unclear. Using zebrafish as a model organism, we demonstrated that zebrafish Ccn6 is present partly as a component of mitochondrial respiratory complexes in the skeletal muscle of zebrafish. Morpholino-mediated depletion of Ccn6 in the skeletal muscle leads to a significant reduction in mitochondrial respiratory complex assembly and activity, which correlates with loss of muscle mitochondrial abundance. These mitochondrial deficiencies are associated with notable architectural and functional anomalies in the zebrafish muscle. Taken together, our results indicate that Ccn6-mediated regulation of mitochondrial respiratory complex assembly/activity and mitochondrial integrity is important for the maintenance of skeletal muscle structure and function in zebrafish. Furthermore, this study suggests that defects related to mitochondrial respiratory complex assembly/activity and integrity could be an underlying cause of muscle weakness and a failed musculoskeletal system in PPRD.

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.

Coexistence of a novel WISP3 pathogenic variant and an MEFV mutation in an Arabic family with progressive pseudorheumatoid dysplasia mimicking polyarticular juvenile idiopathic arthritis

BACKGROUND

A spectrum of rare noninflammatory disorders may present with arthropathy that arises from bony dysplasia, a thickened synovium, and noninflammatory effusion, leading to a constellation of clinical features that mimics chronic polyarticular juvenile idiopathic arthritis (JIA). We report a unique Arabic family harboring a novel pathogenic variant in the WISP3 gene and presenting with progressive pseudorheumatoid dysplasia (PPRD), a rare noninflammatory arthropathy mimicking polyarticular JIA.

CASE PRESENTATION

An Arabic family with PPRD was diagnosed using whole-exome sequencing (WES), revealing a novel c.707delG pathogenic variant in the WISP3 gene. The proband was referred at 10 years old for possible diagnosis of polyarticular JIA based on progressive arthropathy for three years. He was already on naproxen and methotrexate. We suspected familial noninflammatory arthropathy based on clinical manifestations, imaging findings, and family history. WES confirmed the molecular diagnosis of PPRD in the proband and one sister with a similar phenotype. An unexpected p.A744S MEFV pathogenic variant was detected in the proband, parents, and affected sister.

CONCLUSIONS

Early identification and diagnosis of familial noninflammatory arthropathies such as PPRD can prevent unnecessary use of immunosuppressive medications. Diagnosis requires high suspicion in children with early onset arthritic changes, absence of elevated inflammatory markers, specific imaging findings, and positive family history suggestive of an autosomal recessive disorder. We highlight the advantages of WES over single-gene analysis in such cases.

Multiple occurrence of premature polyarticular osteoarthritis in an early medieval Bohemian cemetery (Prague, Czech Republic)

OBJECTIVES

To highlight conditions that may cause early-onset degenerative joint disease, and to assess the possible impact of such diseases upon everyday life.

MATERIAL

Four adults aged under 50 years from a medieval skeletal collection of Prague (Czechia).

METHODS

Visual, osteometric, X-ray, and histological examinations, stable isotope analysis of bone collagen.

RESULTS

All four individuals showed multiple symmetrical degenerative changes, affecting the majority of joints of the postcranial skeleton. Associated dysplastic deformities were observed in all individuals, including bilateral hip dysplasia (n = 1), flattening of the femoral condyles (n = 3), and substantial deformation of the elbows (n = 3). The diet of the affected individuals differed from the contemporary population sample.

CONCLUSIONS

We propose the diagnosis of a mild form of skeletal dysplasia in these four individuals, with multiple epiphyseal dysplasia or type-II collagenopathy linked to premature osteoarthritis as the most probable causes.

SIGNIFICANCE

Combining the skeletal findings with information from the medical literature, this paper defines several characteristic traits which may assist with the diagnosis of skeletal dysplasia in the archaeological record.

LIMITATIONS

As no genetic analysis was performed to confirm the possible kinship of the individuals, it is not possible to definitively assess whether the individuals suffered from the same hereditary condition or from different forms of skeletal dysplasia.

SUGGESTIONS FOR FURTHER RESEARCH

Further studies on premature osteoarthritis in archaeological skeletal series are needed to correct the underrepresentation of these mild forms of dysplasia in past populations.

Novel homozygous variant in WISP3 in a family with unrecognized progressive pseudorheumatoid dysplasia

We present the use of whole-genome sequencing to correctly diagnose progressive pseudorheumatoid dysplasia in patients with atypical clinical and radiologic findings and prior diagnosis of juvenile idiopathic arthritis.

CCN6 regulates mitochondrial respiratory complex assembly and activity

Cellular communication network factor 6 (CCN6) mutations are linked with Progressive Pseudo Rheumatoid Dysplasia (PPRD) a debilitating musculoskeletal disorder. The function of CCN6 and the mechanism of PPRD pathogenesis remain unclear. Accordingly, we focused on the functional characterization of CCN6 and CCN6 mutants. Using size exclusion chromatography and native polyacrylamide gel electrophoresis we demonstrated that CCN6 is present as a component of the mitochondrial respiratory complex in human chondrocyte lines. By means of siRNA-mediated transfection and electron microscopy we showed that moderate reduction in CCN6 expression decreases the RER- mitochondria inter-membrane distance. Parallel native PAGE, immunoblotting and Complex I activity assays furthermore revealed increase in both mitochondrial distribution of CCN6 and mitochondrial respiratory complex assembly/activity in CCN6 depleted cells. CCN6 mutants resembling those linked with PPRD, which were generated by CRISPR-Cas9 technology displayed low level of expression of mutant CCN6 protein and inhibited respiratory complex assembly/activity. Electron microscopy and MTT assay of the mutants revealed abnormal mitochondria and poor cell viability. Taken together, our results indicate that CCN6 regulates mitochondrial respiratory complex assembly/activity as part of the mitochondrial respiratory complex by controlling the proximity of RER with the mitochondria, and CCN6 mutations disrupt mitochondrial respiratory complex assembly/activity resulting in mitochondrial defects and poor cell viability.

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.

A review of skeletal dysplasia research in India

We aimed to review the contributions by Indian researchers to the subspecialty of skeletal dysplasias (SDs). Literature search using specific keywords in PubMed was performed to retrieve all the published literature on SDs as on July 6, 2017. All published literature on SDs wherein at least one author was from an Indian institute was included. Publications were grouped into different categories based on the major emphasis of the research paper. Five hundred and forty publications in English language were retrieved and categorized into five different groups. The publications were categorized as reports based on: (i) phenotypes (n = 437), (ii) mutations (n = 51), (iii) novel genes (n = 9), (iv) therapeutic interventions (n = 31), and (v) reviews (n = 12). Most of the publications were single-patient case reports describing the clinical and radiological features of the patients affected with SDs (n = 352). We enlisted all the significant Indian contributions. We have also highlighted the reports in which Indians have contributed to discovery of new genes and phenotypes. This review highlights the substantial Indian contributions to SD research, which is poised to reach even greater heights given the size and structure of our population, technological advances, and expanding national and international collaborations.

Progressive Pseudorheumatoid Dysplasia resolved by whole exome sequencing: a novel mutation in WISP3 and review of the literature

Background

Progressive pseudorheumatoid dysplasia (PPRD) is a rare autosomal-recessive, non-inflammatory arthropathy, shown to be caused by mutations in the WNT1-inducible signaling pathway protein 3 (WISP3) gene. Although several hundred cases were reported worldwide, the diagnosis remains challenging. Subsequently, the syndrome is often unrecognized and misdiagnosed (for instance, as Juvenile Idiopathic Arthritis), leading to unnecessary procedures and treatments. The objective of the current study was to identify the molecular basis in a family with PPRD and describe their phenotype and course of illness.

Patients and methods

We present here a multiply affected consanguineous family of Iraqi-Jewish descent with PPRD. The proband, a 6.5 years old girl, presented with bilateral symmetric bony enlargements of the 1st interphalangeal joints of the hands, without signs of synovitis. Molecular analysis of the family was pursued using Whole Exome Sequencing (WES) and homozygosity mapping.

Results

WES analysis brought to the identification of a novel homozygous missense mutation (c.257G > T, p.C86F) in the WISP3 gene. Following this diagnosis, an additional 53 years old affected family member was found to harbor the mutation. Two other individuals in the family were reported to have had similar involvement however both had died of unrelated causes.

Conclusion

The reported family underscores the importance of recognition of this unique skeletal dysplasia by clinicians, and especially by pediatric rheumatologists and orthopedic surgeons.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0787-x) contains supplementary material, which is available to authorized users.

Progressive pseudorheumotoid dysplasia: A presentation of four cases with slow and rapid progression and effects of early rehabilitation program

Progressive pseudorheumotoid dysplasia (PPD) is a rare hereditary musculoskeletal disorder which is usually misdiagnosed due to its clinical resemblance to juvenile idiopathic arthritis. It has a high incidence in the Middle East, Gulf States, and countries of Mediterranean basin. Herein, we present four cases of PPD from Turkey (two siblings pair from the same kindred who are far paternal cousins) showing different disease courses. The progression of disease was particularly aggressive in the male sibling who suffered from severe scoliosis with more crippling joint disease. These four cases of PPD support the clinical heterogeneity and variable expressivity of PPD. In this article, we draw attention to the effects of patient education and early rehabilitation which helped to slow progression of range of motion loss.

Progressive pseudorheumatoid dysplasia confirmed by whole-exon sequencing in a Chinese adult before corrective surgery

Background

Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive skeletal dysplasia caused by mutations in the Wnt1-inducible signaling pathway protein 3 (WISP3) gene. Available literatures in PPD emphasized treatment strategy for polyarthritis, while few mentioned spinal deformity and related surgical intervention.

Methods

Here, we present a Chinese man with PPD who underwent spinal surgery twice because of canal stenosis and related symptoms caused by the disease. Whole-exon sequencing (WES) was performed to confirm diagnosis before the second surgery.

Results

A homozygous missense mutation (c.395G>A/p.C132Y) in WISP3 was identified that co-segregated with affected family members.

Conclusions

Our study illustrated a surgical outcome of PPD and highlighted the significance of early diagnosis and individualized surgical strategy, and also verified the value of WES in the diagnosis of PPD.

A Novel Homozygous Frameshift Mutation in CCN6 Causing Progressive Pseudorheumatoid Dysplasia (PPRD) in a Consanguineous Yemeni Family

Background: Progressive pseudorheumatoid dysplasia (PPRD) inherited in an autosomal recessive fashion, is a disabling disease, characterized by platyspondyly, irregularities of the vertebral bodies, narrowing of the intervertebral discs and intraarticular spaces, widening of the epiphysis-metaphysis, polyarthralgia, multiple joint contractures, and disproportionate short stature. A number of studies have been performed on this deformity in various populations around the globe, including the Arab population. Mutations in CCN6, located on 6q22, are reported to cause this anomaly. Case Presentation: The present study describes the investigation of a consanguineous family of Yemeni origin. Clinical examination of the patient revealed short stature with progressive skeletal abnormalities, stiffness and enlargement of small joints of the hands along with restriction of movements of proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints with weakness and gait disturbance. Sanger sequencing revealed a novel homozygous frameshift deletion mutation (c.746delT; p.Val249Glyfs^*10) in CCN6 which may lead to NMD (Nonsense mediated decay). This mutation expands the spectrum of pathogenic variants in CCN6 causing PPRD.

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.

Ilizarov technique in an adolescent patient with progressive pseudorheumatoid dysplasia: A case report

RATIONALE

Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive inherited disease that causes severe systemic joint deformity and articular dysfunction in young patients.

PATIENT CONCERNS

Ilizarov technique treatment in PPD patients has never been reported before.

DIAGNOSES

A 17-year-old male patient presented with a 10-year history of polyarthritis and 4-year history of progressive hip and knee pain and stiffness. Genetic testing for the WISP3 gene was done and showed compound heterozygous mutations: NM_198239.1 (WISP3):c.1064_1065dupGT (p.Gln356ValfsTer33) and NM_198239.1 (WISP3):c.643+2T > C.

INTERVENTIONS

Taking his young age into consideration, the Ilizarov external fixation technique was adopted for the treatment of the deformity in knees.

OUTCOMES

One year after the operation, the improvement of joint deformity was satisfactory.

LESSONS

The Ilizarov technique is economical and less invasive, and most importantly, it can delay the possible arthroplasty. It gives young PPD patients with arthropathy an alternative treatment.

Association analysis on polymorphisms in WISP3 gene and developmental dysplasia of the hip in Han Chinese population: A case-control study

Developmental dysplasia of the hip (DDH) is a common skeletal disorder whereby genetic factors play a role in etiology. Multiple genes have been reported to be associated with the occurrence of DDH. WISP3 gene was found to be a causative gene for progressive pseudorheumatoid dysplasia (PPD). Reports of WISP3 gene in association with DDH are lacking. We conducted a case-control candidate gene association study enrolling three hundred and eighty-six patients with radiology confirmed DDH and 558 healthy controls. Additional haplotype-analysis was conducted to find the significant haplotype for DDH. Five SNPs rs69306665 (upstream of WISP3), rs1022313 (WISP3), rs1230345 (WISP3), rs17073268 (WISP3) and rs10456877 (downstream of WISP3) were identified for association with DDH, showing significant difference of allele frequencies with similar odds ratio ranging from 0.71 to 0.77 (p < 0.01) between cases and controls. Two haplotypes were identified between cases and controls through haplotype analysis: AAAAA with an odds ratio of 0.76 (95% CI: 0.60-0.98, p = 0.032299) and GGCGG with an odds ratio of 1.67 (95% CI: 1.37-2.04, p = 3.67 ∗ 10^-7). The results suggested WISP3 gene was associated with DDH in Chinese Han population. GGCGG haplotype might be a biomarker for DDH.

Noninflammatory disorders mimic juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic childhood arthritis; unfortunately, no diagnostic tool is available. Genetic disorders with musculoskeletal involvement that mimic chronic polyarthritis should be considered in the differential diagnostics of JIA. Normal inflammatory markers and characteristic radiological features are able to distinguish these disorders from JIA. Timely diagnosis of these disorders is crucial to offer the family proper genetic counseling and avoid inappropriate therapy. This review highlights selected noninflammatory disorders that often present with articular manifestations and that are often mislabeled as JIA. The focus is on the clinical, biochemical, and imaging features of these disorders.

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.

Late diagnosis of a truncating WISP3 mutation entails a severe phenotype of progressive pseudorheumatoid dysplasia

Rare diseases are often misdiagnosed or receive a delayed diagnosis; thus, unfortunately, affected individuals may not receive optimal medical management. Here, we report a case of two siblings with a severe phenotype of progressive pseudorheumatoid dysplasia (PPD). Their onset of symptoms began at the age of 3 yr. Both were neglected in the past, and the patients presented with a very severe phenotype and unmitigated natural history. PPD is a rare autosomal recessive skeletal dysplasia characterized by progressive joint stiffness, swelling, and pain. Because of observed muscle wasting, weakness, and the lack of laboratory testing, the case had been initially misdiagnosed by the local physicians. We aimed to provide diagnostic support by a targeted next-generation sequencing gene panel (Illumina TruSight One) for Mendelian diseases (Mendeliome), and we identified a homozygous frameshift mutation in the gene WISP3 (c.868_869delAG, p.Ser290Leufs*12). Thus, early diagnosis and intervention may have decreased the severity and complication of the disease.

Delayed-onset of progressive pseudorheumatoid dysplasia in a Chinese adult with a novel compound WISP3 mutation: a case report

BACKGROUND

Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive genetic disease that is characterized by pain, stiffness and enlargement of multiple joints with an age of onset between 3 and 8 years old. Mutations in the WISP3 (Wnt1-inducible signal pathway) gene are known to be the cause of PPD.

CASE PRESENTATION

We present a case of delayed-onset PPD in a Chinese man. The 35-year-old proband presented with an almost 20-year history of pain and limitations in mobility in multiple joints. Based on the clinical manifestations, the patient was diagnosed with PPD; however, there was no specific evidence to confirm this diagnosis. Through mutational analyses, two WIPS3 mutations in exon 4, including a novel frameshift mutation (c.670dupA) in the paternal allele and an already described nonsense mutation (c.756C > A, p.Cys252*) in the maternal allele, were identified in the proband. Thus, the patient was diagnosed with PPD. Furthermore, we found that the proband's son only carried one of the mutations (c.670dupA) and therefore determined that he would not be affected by PPD in the future.

CONCLUSIONS

In this case, we successfully diagnosed the disease that the proband was affected precisely after the reunion of clinical diagnosis and genetic analysis. These findings demonstrate the clinical utility of genetic analysis to diagnose skeletal dysplasia and guide genetic counseling.

Novel WISP3 mutations causing progressive pseudorheumatoid dysplasia in two Chinese families

Progressive pseudorheumatoid dysplasia (PPD) is a rare disease caused by mutations in the gene for Wnt1-inducible signaling pathway protein 3 (WISP3). Here, we report the clinical and radiographic manifestations of two Chinese PPD patients. We performed whole-exome sequencing for one patient and sequenced the WISP3 for the other. Three WISP3 mutations (c.396T>G, c.721T>G and c.679dup) were identified; the two missense mutations were novel. Our study expanded the WISP3 mutation spectrum.

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

Objectives

To determine the pattern of mutations of the WISP3 gene in clinically identified progressive pseudorheumatoid dysplasia (PPD) in an Indian population.

Patients and Methods

A total of 15 patients with clinical features of PPD were enrolled in this study. Genomic DNA was isolated and polymerase chain reaction performed to amplify the WISP3 gene. Screening for mutations was done by conformation-sensitive gel electrophoresis, beginning with the fifth exon and subsequently proceeding to the remaining exons. Sanger sequencing was performed for both forward and reverse strands to confirm the mutations.

Results

In all, two of the 15 patients had compound heterozygous mutations: one a nonsense mutation c.156C>A (p.C52*) in exon 2, and the other a missense mutation c.677G>T (p.G226V) in exon 4. All others were homozygous, with three bearing a nonsense mutation c.156C>A (p.C52*) in exon 2, three a missense mutation c.233G>A (p.C78Y) in exon 2, five a missense mutation c.1010G>A (p.C337Y) in exon 5, one a nonsense mutation c.348C>A (p.Y116*) in exon 3, and one with a novel deletion mutation c.593_597delATAGA (p.Y198*) in exon 4.

Conclusion

We identified a novel mutation c.593_597delATAGA (p.Y198*) in the fourth exon of the WISP3 gene. We also confirmed c.1010G>A as one of the common mutations in an Indian population with progressive pseudorheumatoid dysplasia.

Cite this article: V. Madhuri, M. Santhanam, K. Rajagopal, L. K. Sugumar, V. Balaji. WISP3 mutational analysis in Indian patients diagnosed with progressive pseudorheumatoid dysplasia and report of a novel mutation at p.Y198* Bone Joint Res 2016;5:301–306. DOI: 10.1302/2046-3758.57.2000520.

Whole Exome Screening Identifies Novel and Recurrent WISP3 Mutations Causing Progressive Pseudorheumatoid Dysplasia in Jammu and Kashmir-India

We report identification and genetic characterization of a rare skeletal disorder that remained unidentified for decades in a village of Jammu and Kashmir, India. The population residing in this region is highly consanguineous and a lack of understanding of the disorder has hindered clinical management and genetic counseling for the many affected individuals in the region. We collected familial information and identified two large extended multiplex pedigrees displaying apparent autosomal recessive inheritance of an uncharacterized skeletal dysplasia. Whole exome sequencing (WES) in members of one pedigree revealed a rare mutation in WISP3:c.156C > A (NP_003871.1:p.Cys52Ter), that perfectly segregated with the disease in the family. To our surprise, Sanger sequencing the WISP3 gene in the second family identified a distinct, novel splice site mutation c.643 + 1G > A, that perfectly segregated with the disease. Combining our next generation sequencing data with careful clinical documentation (familial histories, genetic data, clinical and radiological findings), we have diagnosed the families with Progressive Pseudorheumatoid Dysplasia (PPD). Our results underscore the utility of WES in arriving at definitive diagnoses for rare skeletal dysplasias. This genetic characterization will aid in genetic counseling and management, critically required to curb this rare disorder in the families.

CCN6 regulates mitochondrial function

Despite established links of CCN6, or Wnt induced signaling protein-3 (WISP3), with progressive pseudo rheumatoid dysplasia, functional characterization of CCN6 remains incomplete. In light of the documented negative correlation between accumulation of reactive oxygen species (ROS) and CCN6 expression, we investigated whether CCN6 regulates ROS accumulation through its influence on mitochondrial function. We found that CCN6 localizes to mitochondria, and depletion of CCN6 in the chondrocyte cell line C-28/I2 by using siRNA results in altered mitochondrial electron transport and respiration. Enhanced electron transport chain (ETC) activity of CCN6-depleted cells was reflected by increased mitochondrial ROS levels in association with augmented mitochondrial ATP synthesis, mitochondrial membrane potential and Ca(2+) Additionally, CCN6-depleted cells display ROS-dependent PGC1α (also known as PPARGC1A) induction, which correlates with increased mitochondrial mass and volume density, together with altered mitochondrial morphology. Interestingly, transcription factor Nrf2 (also known as NFE2L2) repressed CCN6 expression. Taken together, our results suggest that CCN6 acts as a molecular brake, which is appropriately balanced by Nrf2, in regulating mitochondrial function.

Biomechanics of walking in adolescents with progressive pseudorheumatoid arthropathy of childhood leads to physical activity recommendations as therapeutic focus

BACKGROUND

Progressive pseudorheumatoid arthropathy of childhood is a rare disease with an estimated prevalence of approximately 1/1,000,000. The disease manifests around the age of three to eight years and progresses with symptoms of early fatigue, muscle weakness, joint swelling and stiffness. The resulting functional limitations are often described as having a waddling gait. Walking is difficult and can be managed with multilevel compensation movements only. Aims of this study were to determine typical malpositions that arise during walking and to identify preventive strategies to reduce excessive joint damage.

METHODS

This study presents data of three-dimensional gait analysis of nine patients with progressive pseudorheumatoid arthropathy of childhood (♀=2; ♂=7; 13.3y; 47.0kg; 1.39m; BMI: 24.2kg/m(2)) performed with eight infrared cameras and the Plug-in-Gait Model. For comparison of spatiotemporal and kinematic parameters with age-matched healthy controls (♀=6; ♂=3; 13.4y; 49.0kg; 1.61m; BMI: 18.9kg/m(2)), the Mann-Whitney U-test was applied with a significance level of P<0.05.

FINDINGS

The patients had a significantly lower height, but higher BMI. Walking speed was reduced with wide, but short steps and significant motion anomalies in the pelvis, hips, knees and ankles. Small ranges of motion in propulsion-supporting movements were typical, especially in the sagittal plane. The gait analysis revealed dominant compensatory movements in pelvic obliquity and rotation.

INTERPRETATION

The deficits can be attributed to pronounced muscle weakness plus functional joint impairment and pain. Therapeutic preventive strategies therefore should consider continuous muscle power exercises, stretching programmes and restrictive weight control.