A novel mutation in the proteoglycan 4 gene causing CACP syndrome: two sisters report.

BACKGROUND: Camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome, caused by biallelic pathogenic mutations in the proteoglycan 4 (PRG4) gene, is characterized by early-onset camptodactyly, noninflammatory arthropathy, coxa vara deformity, and rarely, pericardial effusion. This syndrome can mimic juvenile idiopathic arthritis. CACP syndrome is caused by mutations in the proteoglycan 4 (PRG4) gene. To date, only 36 pathogenic mutations have been reported in this gene, but none have been reported from Azerbaijan. CASE PRESENTATION: Herein, we report two siblings presented with chronic polyarthritis, had a prior diagnosis of juvenile idiopathic arthritis, but was subsequently diagnosed as CACP syndrome with novel mutation in the PRG4 gene. CONCLUSION: Our report expands the knowledge of PRG4 mutations, which will aid in CACP patient counseling.

Monogenic disorders as mimics of juvenile idiopathic arthritis.

BACKGROUND: Juvenile idiopathic arthritis is the most common chronic rheumatic disease of childhood. The term JIA encompasses a heterogenous group of diseases. The variability in phenotype of patients affected by the disease means it is not uncommon for mimics of JIA to be misdiagnosed. CASE PRESENTATION: We present four cases who were treated in single tertiary rheumatology centre for JIA who were subsequently diagnosed with a rare monogenic disease. All four patients shared the unifying features of presenting in early childhood and subsequently suffered with refractory disease, not amenable to usual standards of treatment. Multicentric Carpotarsal Osteolysis Syndrome and Camptodactyly-arthropathy-coxa vara-pericarditis syndrome are non-inflammatory conditions and patients typically present with arthropathy, normal inflammatory markers and atypical radiological features. Blau syndrome is an autosomal dominant condition and patients will typically have symmetrical joint involvement with a strong family history of arthritis, signifying the genetic aetiology. CONCLUSIONS: We share our learning from these cases to add to the growing portfolio of JIA mimics and to highlight when to consider an alternative diagnosis. In cases of refractory disease and diagnostic uncertainty further imaging and genetic testing can play a crucial role in establishing the aetiology. In all of these cases the correct diagnosis was made due to careful, longitudinal clinical phenotyping and a close working relationship between rheumatology, radiology and clinical genetics; highlighting the importance of the multidisciplinary team in managing complex patients.

Genotype-phenotype investigation of 35 patients from 11 unrelated families with camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome.

BACKGROUND: The camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP) is a rare autosomal recessive condition characterized by camptodactyly, noninflammatory arthropathy, coxa vara, and pericarditis. CACP is caused by mutations in the proteoglycan 4 (PRG4) gene, which encodes a lubricating glycoprotein present in the synovial fluid and at the surface of articular cartilage. METHODS: In the present study, we compared the clinical and molecular findings of CACP syndrome in 35 patients from 11 unrelated families. In 28 patients, whole exome sequencing was used to investigate genomic variations. RESULTS: We found that camptodactyly of hands was the first symptom presented by most patients. Swelling of wrists, knees, and elbows began before 4 years of age, while the age of joint involvement was variable. Patients reported an increased pain level after the age of 10, and severe hip involvement developed after 20 years old. All patients presented developmental coxa vara and seven patients (~22%) had pleural effusion, pericarditis, and/or ascites. We identified nine novel genomic alterations, including the first case of homozygous complete deletion of exon 1 in the PRG4 gene. CONCLUSION: With this study, we contribute to the catalog of CACP causing variants. We confirm that the skeletal component of this disease worsens with age, and presents the potential mechanisms for interfamily variability, by discussing the influence of a modifier gene and escape from nonsense-mediated mRNA decay. We believe that this report will increase awareness of this familial arthropathic condition and the characteristic clinical and radiological findings will facilitate the differentiation from the common childhood rheumatic diseases such as juvenile idiopathic arthritis.

Brothers with constrictive pericarditis - A novel mutation in a rare disease.

Familial constrictive pericarditis is extremely rare. We report a case of two brothers both suffering constrictive pericarditis along with having multiple painless joint deformities. Genetic workup confirmed the clinical diagnosis of camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome CACP syndrome and also revealed a rare mutation in the causative gene.

Protein-losing enteropathy in camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome.

BACKGROUND: Camptodactyly-arthropathy-coxa vara-pericarditis (CACP, OMIM: #208250) syndrome is a rare autosomal recessive disease that can be difficult to recognise not only because of its wide clinical variability but also because of its clinical resemblance to juvenile idiopathic arthritis (JIA). PRG4 is the only gene so far known to be associated with CACP syndrome. Children with CACP syndrome lack the glycoprotein lubricin due to recessive mutations in PRG4. Lubricin serves as a lubricant in joints, tendons and visceral cavities (pleural cavity, pericardium) and inhibits synovial proliferation. Children with CACP syndrome suffer from congenital camptodactyly, arthropathy, coxa vara and sometimes pericarditis. This report concerns a child with CACP syndrome complicated by protein-losing enteropathy (PLE), caused by constrictive pericarditis and so contributes to knowledge of the presentation of CACP syndrome. CASE PRESENTATION: A 10- year-old girl with consanguineous parents suffered from congenital camptodactyly and progressive swollen and painful joints. Her father and his sister had similar childhood-onset joint complaints. Laboratory tests showed no signs of inflammation but showed persistent low protein- and IgG- levels, indicating a secondary immunodeficiency. Increased alpha antitrypsin clearance confirmed PLE. Abdominal ultrasound with Doppler showed hepatomegaly and portal hypertension. Echocardiography suggested constrictive pericarditis. However, heart catheterization could not confirm this. Ultrasound and X-ray examination of the joints combined with a puncture of the synovial fluid were performed. These results, combined with the clinical presentation and the consanguinity, suggested CACP syndrome. Due to excessive enteral protein losses, the patient was treated with Cotrimoxazol prophylaxis and immunoglobulin supplements. These supplements were inadequate to achieve normal IgG values. As constrictive pericarditis with subsequent PLE was the best explanation for the excessive IgG losses, pericardiectomy was performed with good results. Genetic testing in our patient was complicated but revealed a pathogenic mutation within the repeat sequence in exon 7 of the PRG4 gene. CONCLUSION: PLE resulting from constrictive pericarditis can be a complication of CACP syndrome. As serious complications can arise from the resulting secondary immunodeficiency, we recommend regular evaluation of clinical symptoms of constrictive pericarditis and PLE in children with CACP syndrome.

Spondyloepiphyseal dysplasia congenita caused by double heterozygous mutations in COL2A1.

Spondyloepiphyseal dysplasia congenita (SEDC) is a group of rare inherited chondrodysplasias characterized by short stature, abnormal epiphyses, and flattened vertebral bodies. SEDC is usually caused by substitution of glycine residue with another amino acid in the triple helical domains of alpha 1 chains, which consist of type II collagen (COL2A1). Herein, we describe a unique case of SEDC with mild coxa vara (SEDC-M) caused by double de novo COL2A1 mutations located on the same allele. One mutation, p.G504S, was previously described in patients with SEDC, whereas the other, p.G612A, was a novel mutation; both were located in the triple helical domain. Neither mutation was identified in the parents and appeared to be de novo. To the best of our knowledge, this is the first study involving a patient with a type II collagenopathy with two COL2A1 mutations on the same allele. The case was characterized by a more severe phenotype compared with previously reported cases involving a single p.G504S mutation, which may have been the result of the double mutation.

Novel mutations in PRG4 gene in two Indian families with camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome.

BACKGROUND & OBJECTIVES: Camptodactyly--arthropathy-coxa vara-pericarditis (CACP) syndrome is an autosomal recessive disorder caused by mutations in the PRG4 (proteoglycan 4) gene. Hallmarks of the syndrome include congenital or early-onset camptodactyly and arthropathy with synovial hyperplasia, progressive coxa vara deformity and non-inflammatory pericardial effusions. Till date only around 25 pathogenic mutations have been reported in this gene and none have been reported from India. We report here the mutations in the PRG4 gene in three patients of CACP from two unrelated families from India. METHODS: Molecular genetic studies were done for the three patients with the CACP syndrome, from two unrelated Indian families, through sequence analysis of all coding exons and the exon-intron boundaries of the PRG4 gene. RESULTS: Two novel frame-shift deletion mutations leading to premature protein termination were found. One patient was identified to be homozygous for a 2 base pair deletion in exon 6 (c.2645_2646delGA) and the two affected siblings from the other family were found to be homozygous for a 4 base pair deletion in exon 6 (c.2883_2886delAAGA). CONCLUSIONS: This is perhaps the first report of PRG4 mutations from India. Further mutation studies in Indian CACP cases will help to determine the mutation spectrum of the PRG4 gene in the Indian population and also help to further elucidate the molecular pathology and the genotype-phenotype correlation of this rare disease.

CACP syndrome: identification of five novel mutations and of the first case of UPD in the largest European cohort.

Camptodactyly-Arthropathy-Coxa vara-Pericarditis (CACP) syndrome is a rare autosomal recessive disorder caused by mutations in PRG4 gene that encodes for proteoglycan 4, a mucin-like glycoprotein that is the major lubricant for joints and tendon surfaces. The molecular studies reported so far have described the identification of 15 mutations associated with this syndrome and the majority of them were found in families of Arabian origin. Here we report the molecular investigation of the largest European cohort that comprises 13 patients, and allowed the identification of 5 novel mutations and of the first case of CACP syndrome resulting from uniparental disomy of chromosome 1.

Axial correction of the lower limb deformities in a girl with anauxetic dysplasia.

Valgus subtrochanteric osteotomies and hemiepiphyseodesis around the knees have been performed to correct severe coxa vara and genua valga in a girl patient who manifested extreme dwarfism associated with spondylometaepiphyseal dysplasia consistent with anauxetic dysplasia. To the best of our knowledge, this is the first description of the combined orthopaedic intervention in a girl with anauxetic dysplasia.

Camptodactyly-arthropathy-coxavara-pericarditis syndrome in Saudi Arabia: clinical and molecular genetic findings in 22 patients.

BACKGROUND: Camptodactyly-arthropathy-coxavara-pericarditis (CACP) syndrome is a rare autosomal recessive disorder caused by mutations in the gene proteoglycan 4 (PRG4), affecting lubricin production, which is an essential protein for joint function. Manifestations vary between affected individuals with camptodactyly, early-onsetnon-inflammatory arthropathy, coxa vara deformity and non-inflammatory pericarditis. OBJECTIVE: To describe the clinical, laboratory, radiological and genetic findings of CACP syndrome in children from Saudi Arabia. METHODS: Medical records of all the children with CACP syndrome seen between June 1990 and June 2012 at King Faisal Specialist Hospital and Research Center, Riyadh were reviewed. The data include gender,age of first disease manifestations,referral diagnosis, clinical and radiological features, and molecular genetic studies as well as functional status at the last follow-upvisit. RESULTS: Twenty-two patients (15 boys), (clinical and genetic data of 15 patients were previously published) with mean age at diagnosis 3.7 (1-14) years, were included in this cohort study. The referral diagnosis was inaccurate in all patients; juvenile idiopathic arthritis (JIA) was the referral diagnosis in majority of the patients. Six families had more than one affected child. Camptodactyly and large joints arthropathy were present in all the cases. Camptodactyly was observed in the neonatal period in all the patients, while other joint involvement was observed through the 1st year of life. All patients had a normal cardiac evaluation but two children had evidence of pericarditis. All patients had normal inflammatory markers and the result for rheumatoid factor test was negative. Radiological findings included coxa vara with a short femoral neck and flat, irregular femoral heads and intra-osseous cysts, increased joint space, and abnormal modeling of the acetabulum with small iliac wings. Other joints (knees, ankle, elbow and wrist) showed soft-tissue swelling consistent with thick cartilage and abnormal modeling with evidence of intra-articular fluid in majority of the patients. Synovial biopsy from three patients revealed proliferating synovial epithelium with moderate fibro-collagenous densities and multinucleated giant cells, occasional lymphocytes or neutrophils were identified. Previously, a locus responsible for causing CACP syndrome has been reported in eight patients of our cohort; it has been assigned to 1q25-q31. Furthermore, in seven newly diagnosed patients from four unrelated families, five novel mutations were found. All patients were referred to us while they were on NSAIDs, 10 patients used antirheumatic drugs (prednisone and methotrexate) and two patients were treated with etanercept. In all patients, treatment was ineffective apart from mild pain relief. CONCLUSION: CACP syndrome is an autosomal recessive disorder occurring due to mutations in the gene PRG4 encoding lubricin; it is not an uncommon disorder in Saudi Arabia. Pericarditis is rarely seen in our patients. Our data suggest that CACP syndrome may be easily confused with JIA, causing a delay in diagnosis and probably unnecessary treatment with antirheumatic drugs including biologic agents.

A novel mutation in PRG4 gene underlying camptodactyly-arthropathy-coxa vara-pericarditis syndrome with the possible expansion of the phenotype to include congenital cataract.

BACKGROUND: Camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP) is a clinically heterogenous congenital disorder caused by mutations in proteoglycan 4 (PRG4), a chondroitin sulfate proteoglycan that acts as a lubricant for the cartilage surface. Although CACP is a rare genetic disorder, several cases were described in the literature from ethnically different populations including Caucasian, Egyptian, Saudi Arabian, Pakistani, and Korean. We report CACP for the first time in United Arab Emirates. METHODS: Direct sequencing of all the coding exons and splice sites of the PRG4 gene was performed for all the members of the affected family. RESULTS: The studied family is consanguineous and has multiple affected members from different branches showing congenital camptodactyly with arthropathy, the hallmarks of CACP. All the affected family members lack pericarditis, but one of them was born with cataract, which has never been documented in any of the previously reported cases of CACP. Molecular analysis revealed a novel homozygous insertion of a cytosine nucleotide (c.1320dupC) in the highly repetitive portion of the coding sequence of the PRG4 gene. The detected mutation caused a frameshift in the cDNA sequence and created a premature termination codon (p.P440fsX197), which is likely to result in a nonfunctional protein. CONCLUSION: We report a family from the United Arab Emirates with typical features of CACP in whom one of the children had in addition, a bilateral congenital cataract. We also report the identification of a novel null mutation in PRG4 confirming the genetic homogeneity of CACP.