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

Abstract

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.

Keywords: Platyspondyly; Progressive pseudorheumatoid dysplasia; Spondyloepiphyseal dysplasia; WISP3; c.1010G>A (p.C337Y).

Clinical photographs of a 13-year-old girl, which show that a) unique to PPD, the limitation of ankle movement is mainly in plantar flexion; b) classical epiphyseal swelling of the interphalangeal joints with stiffness but without pain is seen in the same patient; c) the same patient shows an enlarged posterior process of the talus which appears early and fuses before ten years of age.

Radiographs showing a) the pelvis of an 11-year-old girl showing lateralisation of the femoral head on the left side. There is altered growth on the capital femoral physis and flexion deformity. The hip protrusio is not seen, which distinguishes PPD from juvenile rheumatoid arthritis; b) the ankle of a nine-year-old boy shows near fusion of the enlarged posterior process of talus. Normal fusion of posterior process of the talus in boys usually occurs after 11 years; c) hand of an 11-year-old girl showing metaphyseal widening and epiphyseal shortening most prominent in the proximal interphalangeal joints and flexion deformity of the distal interphalangeal joint of the 5th digit, with an enlarged soft-tissue shadow with loss of joint space. The ulnar styloid process is hooked like a parrot’s beak in this child. The distal radial physis is flattened and the wrist joint is irregular; d) spine of 12-year-old girl showing platyspondyly with inferior and central beaking. There is a grade I L5-S1 spondylolisthesis. The lumbar vertebrae show inferior, and thoracic vertebrae show central, beaking.

Fig. 3

Conformation-sensitive gel electrophoresis for six patients. The fourth patient (P4) shows a heteroduplex band indicated by the white arrow above the normal band of exon 5 (white arrow), indicating a mutation in the fifth exon of the WISP3 gene.

Direct sequencing of fifth exon of the WISP3 gene in the fourth patient; (a) showed the presence of homozygous missense mutation c.1010G>A (p.C337Y) when compared with (b) control.

Direct sequencing of fourth exon of the WISP 3 gene in the fifteenth patient shows (a) the absence of ATAGA sequence (black arrow) in the forward strand, indicating a deletion mutation c. 593_597delATAGA (p.Y198*); b) confirmation of this mutation was obtained by sequencing the reverse strand and; c) normal ATAGA sequence was seen in the control sample (black arrow).