Progressive pseudorheumatoid dysplasia confirmed by whole-exon sequencing in a Chinese adult before corrective surgery
- 196 Downloads
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.
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.
A homozygous missense mutation (c.395G>A/p.C132Y) in WISP3 was identified that co-segregated with affected family members.
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.
KeywordsProgressive pseudorheumatoid dysplasia Whole-exon sequencing Spinal surgery
Human Gene Mutation Database
Juvenile rheumatoid arthritis
Minor allele frequency
Online Mendelian Inheritance in Man
Progressive pseudorheumatoid dysplasia
Visual analogue scale
Wnt1-inducible signaling pathway protein 3
Progressive pseudorheumatoid dysplasia (PPD) is an autosomal recessive disease characterized by spondyloepiphyseal dysplasia associated with progressive joint deformities, pain, stiffness, and swelling mainly in the spine and hip joints . PPD is caused by mutation in the Wnt1-inducible signaling pathway protein 3 (WISP3) gene, which consists of five exons and encodes a 354 amino acid protein . WISP3 belongs to the connective tissue growth factor (CCN) gene family, and the encoded protein plays an essential role in skeletal growth and cartilage homeostasis . This disease is usually misdiagnosed as juvenile idiopathic arthritis or juvenile rheumatoid arthritis (JRA), and patients can receive many years of unnecessary treatment before correct diagnosis .
Whole-exon sequencing (WES) is useful for identifying rare monogenic inherited diseases , and the reducing cost of WES has improved the feasibility of its clinical use . In this study, we employed WES to explore the potential causative genes in a Chinese PPD patient who underwent spinal surgical treatment twice.
The proband’s height and weight were 162 cm and 72.5 kg when he was admitted to our hospital. His visual analogue scale (VAS) score was 9. He did not have behavioral difficulties and was not retarded in his intellectual development. Physical examination showed multiple malformations of the major limb joints, especially of the knees and hands (Fig. 2). Amyotrophy of both lower limbs was obvious. Cervical and lumbar movements were limited with compensatory kyphosis. The muscular strength of all four limbs was normal. Dysesthesia was found in the posterolateral left calf, dorsolateral left foot, and perineal area. Bilateral knee-jerk reflexes and ankle reflexes were hypo-induced. The erythrocyte sedimentation rate (13 mm/h) and C-reactive protein level (2 mg/L) were both within the normal range. Tests for rheumatoid factors were negative.
Blood samples were taken from the proband and from direct consanguineous relatives from three generations after an informed consent was obtained. DNA was extracted using a centrifuge column method (Tiangen, Beijing, China) and was qualitatively and quantitatively assessed by standard techniques before use in whole-exome sequencing.
All exons were captured using the Roche NimbleGen human exon V2 capture chip (Roche, Pleasanton, CA, USA) according to the manufacturer’s protocols, and sequencing data was obtained using the Roche NimbleGen human exon V2 capture chip on the Illumina HiSeq 2500 platform (Illumina Inc.).
The putative mutation was validated by Sanger sequencing in the proband and four family members. The following PCR primers were designed using Primer 6.0 software (PREMIER Biosoft International, CA, USA): forward (CAGGGCACTGGACCATTAGA) and reverse (CCCACTGGTGCATGAAAACTAA). PCR products were purified and sequenced on an ABI 3130XL (Applied Biosystems). The results are shown in Fig. 4.
Before the second surgery, WES was performed and a conclusive diagnosis of PPD was developed. WES covered 99.8% of target regions with a mean depth of on-target reads of × 105. A total of 44,397 raw variant calls were detected, and after removing variants with low quality (see the “Methods” section), 39,924 remained. Using the 1000 Genomes and ExAc databases, 1486 were selected as rare variants, 79.0% of which were excluded as known SNPs. Also excluded were 140 synonymous variants, while 71 benign or neutral variants were filtered out by PolyPhen-2 and SIFT. One rare variant (c.395G>A/p.C132Y) located in exon 3 of WISP3 was identified as associated with skeletal dysplasia. Sanger sequencing confirmed this homozygous mutation co-segregated with affected family members (Fig. 4). This mutation resulted in the substitution of a cysteine with a tyrosine at position 132 and was predicted by Polyphen-2 as probably damaging with a score of 1.0 and damaging by SIFT with a score of 0. As shown in Fig. 4, this amino acid change affected a highly conserved residue.
PPD is a rare autosomal recessive disease, with an estimated population incidence in the UK of one per million . In this study, we presented a family showing PPD and a patient undergoing spinal surgery twice. WES identified a missense mutation in WISP3, enabling a definitive diagnosis. We believe that this is the first presentation of a PPD patient receiving spinal surgery twice.
Patients with PPD are asymptomatic after birth and during early childhood, with symptoms often appearing between the age of 4 and 6 years [7, 8]. Because PPD patients are asymptomatic in the first years of life, the disease is usually misdiagnosed as mucolipidosis type IV and juvenile rheumatoid arthritis . The typical clinical manifestations and radiographic findings in PPD include progressive deformities, pain, stiffness, and swelling of multiple joints, notably in the wrists, fingers, hips, and knees, with the absence of destructive bone changes . To date, there is still no radical treatment for PPD and surgical treatment can be performed in individuals who might benefit. In our patient, the hypogenetic spine presented coin-like flat vertebral bodies, short pedicles, and kyphosis. These deformities resulted in developmental spinal canal stenosis. The degenerative changes, such as disc herniation and hypertrophic ligamentum flavum, worsened the spinal canal stenosis and gradually led to clinical symptoms. Spinal surgery aiming to decompress the spinal canal was inevitable if non-surgical intervention failed. Our patient also had developmental spinal canal stenosis and conspicuous spinal symptoms. He underwent lumbar spine and thoracic spine surgery successively. Available reports on the treatment for PPD focus more on hip joint replacement surgery, and this is the first reported sequential lumbar and thoracic spinal surgery. Meanwhile, vertebral body deformities, maldevelopment of the pedicles and segmental kyphosis, increased the difficulty of the spinal surgery. We noticed that muscle weakness did not improve after the second surgery, indicating the importance of early diagnosis and rehabilitation intervention.
WISP3 belongs to the CCN family, which encodes multimodular mosaic proteins. To date, 51 mutations have been identified in WISP3, including missense, nonsense, frameshift, and exon-deletion mutations (the Human Gene Mutation Database (HGMD)), indicating that loss of WISP3 function leads to PPD. Our study is consistent with another report of a Chinese patient with a similar phenotype and a WISP3 p.C132Y mutation , which indicates this variant as a mutation hotpoint in the Chinese population. WISP3 functions in the synthesis of chondrocyte saccharin and collagen type II , which are the major components of cartilaginous tissue. The loss of WISP3 function can result in cartilage lesion.
WES enabled us to conclusively diagnose PPD in this patient and may provide wider clinical use in this field. With its decreasing cost, WES is increasingly used for diagnostic purposes in the clinical setting with a 25.2% diagnosis rate in a consecutive patient cohort . With appropriate data filtering and pedigree mapping, WES can help develop diagnoses, especially in rare Mendelian diseases like PPD, which will help prevent the administration of unnecessary treatments . Our study further verified the value of WES in the diagnosis of PPD. With the diagnosis of PPD, we were able to develop proper surgical strategy and anticipate complexity of surgery before the second procedure. Due to coin-like flat vertebral bodies of PPD, precisely applying pedicle screw should be pre-designed before surgery . And since developmental spinal canal stenosis was induced by short pedicles in PPD, associated cervical, thoracic, and lumbar neurological symptoms may deteriorate over time with degenerative changes. As a result, spinal decompression range should be decided not only on the radiological imaging, but also on clinical manifestations. Favorable prognosis in PPD patients was also composed by patient education in early intervention of myelopathy and anti-osteoporosis medications.
In conclusion, our study describes a PPD patient who underwent spinal surgery twice. Meanwhile, WES was used efficiently to identify causative mutations in PPD, thus informing a definitive diagnosis and enabling individualized surgical strategy.
The authors are indebted to the individuals whose participation made this study possible. We would like to acknowledge Dr. Wei Liu and Dr. Siqian Gong (both from Peking University People’s Hospital) for their generous help with gene mutation analysis.
This research was supported by Natural Science Foundation of Beijing Municipality (A73509-03).
Availability of data and materials
Datasets used in this study are available from the corresponding author.
YL initiated the idea, did the data analysis, and wrote the assay. YZ supervised and reviewed the manuscript, and also provided the funding. ZC supervised the study. HX and XL gathered the data and helped with the data analysis. All authors read and approved the final manuscript.
Ethics approval and consent to participate
This study was approved by the Peking University Third Hospital Ethical Committee and taken out under the direction of Declaration of Helsinki. Written consents were obtained from all the participants.
Consent for publication
Consent for publication had been obtained from the participants.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- 2.Hurvitz JR, Suwairi WM, Van Hul W, El-Shanti H, Superti-Furga A, Roudier J, Holderbaum D, Pauli RM, Herd JK, Van Hul EV, Rezai-Delui H, Legius E, Le Merrer M, Al-Alami J, Bahabri SA, Warman ML. Mutations in the CCN gene family member WISP3 cause progressive pseudorheumatoid dysplasia. Nat Genet. 1999;23:94–8.CrossRefGoogle Scholar
- 4.Garcia Segarra N, Mittaz L, Campos-Xavier AB, Bartels CF, Tuysuz B, Alanay Y, Cimaz R, Cormier-Daire V, Di Rocco M, Duba HC, Elcioglu NH, Forzano F, Hospach T, Kilic E, Kuemmerle-Deschner JB, Mortier G, Mrusek S, Nampoothiri S, Obersztyn E, Pauli RM, Selicorni A, Tenconi R, Unger S, Utine GE, Wright M, Zabel B, Warman ML, Superti-Furga A, Bonafé L. The diagnostic challenge of progressive pseudorheumatoid dysplasia (PPRD): a review of clinical features, radiographic features, and WISP3 mutations in 63 affected individuals. Am J Med Genet C Semin Med Genet. 2012;160C:217–29.CrossRefGoogle Scholar
- 5.Yang Y, Muzny DM, Xia F, Niu Z, Person R, Ding Y, Ward P, Braxton A, Wang M, Buhay C, Veeraraghavan N, Hawes A, Chiang T, Leduc M, Beuten J, Zhang J, He W, Scull J, Willis A, Landsverk M, Craigen WJ, Bekheirnia MR, Stray-Pedersen A, Liu P, Wen S, Alcaraz W, Cui H, Walkiewicz M, Reid J, Bainbridge M, Patel A, Boerwinkle E, Beaudet AL, Lupski JR, Plon SE, Gibbs RA, Eng CM. Molecular findings among patients referred for clinical whole-exon sequencing. JAMA. 2014;312:1870–9.Google Scholar
- 6.Monroe GR, Frederix GW, Savelberg SM, de Vries TI, Duran KJ, van der Smagt JJ, Terhal PA, van Hasselt PM, Kroes HY, Verhoeven-Duif NM, Nijman IJ, Carbo EC, van Gassen KL, Knoers NV, Hövels AM, van Haelst MM, Visser G, van Haaften G. Effectiveness of whole-exon sequencing and costs of the traditional diagnostic trajectory in children with intellectual disability. Genet Med. 2016;18:949–56.CrossRefGoogle Scholar
- 12.Yang Y, Muzny DM, Reid JG, Bainbridge MN, Willis A, Ward PA, Braxton A, Beuten J, Xia F, Niu Z, et al. Clinical whole-exome sequencing for the diagnosis of mendelian disorders. N Engl J Med. 2013;369:1502–11.Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.