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Keywords:

  • Arg75-Cys mutation;
  • COL2A1;
  • Phenotype

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Objective

To define the clinical, radiologic, and molecular genetic characteristics of a family with early progressive osteoarthritis mimicking childhood rheumatoid arthritis, Scheuermann-like changes of the spine, tall stature, short 3 and 4 metatarsals, and moderate sensorineural hearing loss.

Methods

We describe a 22-year-old woman and her 54-year-old mother with early progressive osteoarthritis mimicking childhood rheumatoid arthritis. The index case, her mother, and 3 other family members underwent a physical examination, anthropometric measurements, and radiologic studies. Their DNA was sequenced for the procollagen type II (COL2A1) gene.

Results

Mild scoliosis was noticed in the proband at the age of 6 years, and at the age of 7 years large Schmorl's nodes were found in the vertebrae L1-2. At the age of 11 years, changes resembling Scheuermann's disease were seen, mostly in the thoracic vertebrae. At the same age, she began to have arthralgia in the weight-bearing joints and osteoarthritis progressed fast, necessitating a hip prosthesis at the age of 18 years. The proband and her mother had bilateral sensorineural hearing loss of moderate degree. Both mother and daughter had an Arg75-Cys mutation in the COL2A1 gene.

Conclusion

This family is the fourth example of the Arg75-Cys mutation in the COL2A1 gene, which appears to lead to a clearly recognizable phenotype. The finding suggests that sensorineural hearing loss may be a part of this syndrome.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Skeletal dysplasias are a large and heterogeneous group of disorders. There are currently >100 recognized forms of skeletal dysplasia (1). Among them, type II collagenopathies have been classified as a separate group (2). Type II collagenopathies are heterogeneous and their severity is variable.

The procollagen type II gene (COL2A1) has been targeted for extensive analysis in degenerative diseases of the joint because of its abundance in epiphyseal and articular cartilage tissue (3). The majority of the mutations found in COL2A1 are missense mutations in which glysine is usually replaced by a bulkier amino acid (4). Among the nonglysine missense mutations, the arginine-to-cysteine substitutions predominate (5). There are now 3 sites along the COL2A1 where arginine-to-cysteine mutations have been detected: in exons 11, 31, and 41 (6–12). Representing all these positions there are multiple, apparently unrelated, families with identical mutations (13). A point mutation, Arg75-Cys, has been found in exon 11 in 3 families in Chiloe Island, France, and the United States (5, 8, 11, 14).

We describe the fourth family with premature osteoarthritis with mild spinal chondrodysplasia and COL2A1 mutation in exon 11 leading to an Arg75-Cys replacement. Our findings provide further proof of the very specific phenotype caused by this mutation and suggest that sensorineural hearing loss may be a part of this syndrome.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Patients.

The index case, a 22-year-old woman, had a history of normal gestation, birth, and early development. Her height exceeded the +2 SD curve since 7 years of age.

At the age of 6 years a mild scoliosis was noticed. The first spinal radiograph, at the age of 7 years, showed flattened lumbar vertebral bodies with large Schmorl's nodes in the vertebrae L1-2 (Figure 1A) (15, 16). At the age of 11 years, kyphoscoliosis was 40° and the vertebral bodies, especially T7, were flattened and anteriorly wedged, resembling Scheuermann's disease (Figure 1B). The endplates of the vertebrae were irregular and the intervertebral disc spaces were slightly narrowed.

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Figure 1. Radiography of the lumbal spine of the index case at 7 years and of the thoracic spine at 11 years. A,At 7 years, the lumbar vertebral bodies were flattened and large; Schmorl's nodes were seen in the upper endplates of the bodies L1-2. B,At 11 years, the thoracic vertebral bodies were flattened and there were wedgings of different grades, most severe in T7 vertebrae. The endplates were uneven.

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At the same age she began to have symptoms in the weight-bearing joints, beginning with the hips, clinically resembling rheumatoid arthritis, e.g., pain, stiffness, and accumulation of excess synovial fluid (hydrops) that could be seen on ultrasound examination. Radiologic findings of the hips were normal at the age of 11 years (Figure 2A). Within 2 years, radiologic signs of osteoarthritis developed: the joint spaces were narrowed, there were osteophytes, intraarticular soft tissue calcifications, and periosteal calcification layers (Figure 2B). At the age of 18 years, the osteoarthritis had progressed further (Figure 2C) and a hip prosthesis was placed in the left hip; at the age of 21 years, a prosthesis was placed in the right hip. Osteoarthritis of the knees was also observed at the age of 18 years. The joint space of the right knee had narrowed and there were osteophytes. The findings in the left knee were less severe.

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Figure 2. The fast progress of osteoarthritis in the hip joints. A, Normal findings at the age of 11 years. B, The hip joint space was narrowed at the age of 13 years. There were intraarticular soft tissue calcification particles laterally and a periosteal calcification layer medially from the femoral neck. C, Osteoarthritis was very serious at the age of 18 years.

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Mild-to-moderate bilateral sensorineural hearing loss was diagnosed at the age of 8 years and she got hearing aids (Figure 3). Later, to investigate the etiology of the hearing impairment, the connexin-26 gene was sequenced and no mutations were found. There was no myopia and an ophtalmologic investigation at the age of 15 years showed normal findings. In orthopantomography at the age of 10 years, the teeth were crowded and the condyles of the mandible were a little flat anteriorly.

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Figure 3. The audiogram of the index patient showed sensorineural hearing loss in both ears. The dot/lines show means.

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In the early years, no toe abnormalities were recorded by a pediatrician or the parents. Before school age, the parents noticed that the third and fourth toes in both feet remained shorter. This was seen radiologically at the age of 11 years, when the distal epiphyseal lines of the metatarsal bones of the third and fourth toes were prematurely fused and brachymetatarsia of the third and fourth toes developed. The epiphyseal lines of the neighboring metatarsal bones still remained open (Figure 4). Both halluces were in the valgus position.

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Figure 4. Toes 3 and 4 were short and distal epiphyseal lines of the 3 and 4 metatarsal bones are closed. The lines of metatarsals 2 and 5 were still open at the age of 11 years.

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At the age of 11 years, bone age was slightly (+1.6 SD) advanced according to Greulich and Pyle (17). Radiologically, the hands and wrists as well as the epiphyses of long bones were normal.

At clinical examination at the age of 20 years she was tall (177.0 cm [+2.1 SD]) with a target height of +1.5 SD (father 185 cm, mother 174 cm). Her weight was 63 kg (+3%), and her arm span was 185.5 cm. She had a reduced upper to lower segment ratio of 0.77 (–1 SD). She had a small mandible, high arched palate, and retrognathia. There were flexion contractures in both hips and ankylosis in both knees (Figure 5A). Severe hallux valgus was observed in both feet, and the third and fourth toes were short even after the elongation of both third and fourth metatarsal bones (Figure 5B). Both walking and everyday living had been better after left hip prosthesis insertion. At age 21, the right hip was replaced. Her vision was normal. School performance had been normal.

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Figure 5. Photographs of the index case at the age of 14 years 3 months. A, Front view. B, Metatarsals.

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The mother of the index case had been diagnosed as having rheumatoid arthritis at the age of 5 years. At the age of 18 years, osteochondritis dissecans was detected in both knees and arthrotomy was performed on the right side. At the age of 26 years, she had severe limitation in the rotation and adduction and milder limitation in abduction of both hips. She also had limitations in the movements of the shoulders, elbows, and knees. In the radiogram, the vertebral bones of the thoracic spine were flattened. In both hips the joint space had almost disappeared, the femoral head was deformed, and there were intra- and extraarticular calcific deposits in the right hip. The sacroiliac joints were unremarkable. In both knees, there was narrowing of the joint space, flattening of the intercondylar notch, and calcification. Narrowing of the joint space was also seen in the shoulders and elbows. The osteoarthrosis progressed so that hip prostheses had been installed for the first time at the age of 28 years on the right side and at the age of 29 years on the left side. Knee prostheses had been installed at the age of 37 years on the left side and at the age of 46 years on the right side. The right hip prosthesis had had to be changed at the ages of 48 and 50 years.

At clinical examination at the age of 54 years, she was tall (174 cm) and her weight was 80 kg. Her arm span was normal (172.8 cm). She also had brachymetatarsia, although it was not as marked as in the daughter. She had severe limitation of movement in all weight-bearing joints and also in the cervical spine, shoulders, elbows, and wrists, but she could walk slowly with 1 stick. Her vision was normal. She had also sensorineural hearing loss of moderate degree detected at the age of 40 years.

The index patient had 1 healthy sister who showed no abnormalities on clinical examination, and neither did a maternal brother and his son. Their mutation analysis showed normal results. The maternal grandmother had died at a young age due to rheumatic fever. There were 3 more distant maternal relatives with history of either hip prosthesis or rheumatoid arthritis, but they could not be contacted for our study.

Methods.

Genomic DNA was extracted from peripheral blood samples of the proband, her mother, and 3 unaffected family members by using the PUREGENE DNA extraction kit (Gentra Systems Inc., Minneapolis, MN). Because the clinical picture resembled the one published by Williams et al in 1993 (11), only exon 11 of the COL2A1 gene was analyzed as previously described (18). A polymerase chain reaction (PCR) was performed using primers annealing to introns 10 and 11. The primer sequences were as follows: 5′CCT GGT GGC GAA GGG AAC TG 3′ for the upstream primer in intron 10 and 5′AGT TGG AAG AAA TGC ACG CAC 3′ for the downstream primer in intron 11. These primers were designed to amplify a product of the size 237 bp. The reaction conditions were: 94°C for 5 minutes, 94°C for 1 minute, 62°C for 1 minute, 72°C for 1.30 minutes for 30 cycles, after which extension was at 72°C for 10 minutes (DNA Engine PTC-200; MJ Research, Waltham, MA). The PCR product was purified using the QIAquick PCR purification kit (Qiagen GmbH, Hilden, Germany). The purified PCR product was then sequenced using the SequiTherm Excel II DNA Sequencing Kit-LC kit (Epicentre Technologies, Madison, WI). For sequencing analysis, the Li-Cor 4200 sequencer was used (Li-Cor Inc., Lincoln, NE).

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Bidirectional DNA sequencing of the PCR product for exon 11 of the COL2A1 gene showed a transition of a C to T in 1 allele. The C to T transition converts a codon for arginine75 into a codon for cysteine in the proband and her mother (Figure 6). The mutation was not found in the healthy sister of the proband, her maternal uncle (the only sibling of the mother), or in the maternal uncle's son.

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Figure 6. Sequence analysis of the index patient (left), her mother (middle), and a control person (right) in reverse direction showed the conversion of codon CGT to TGT at position 75 of exon 11 in the procollagen type II (COL2A1) gene (arrow).

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DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

The main clinical findings of our proband and her mother were early osteoarthritis, tall stature, hearing loss, distinct facial features, and short metatarsals. The clinical picture closely resembled the families described by Williams et al (11) and Reginato et al (14), reported as having an Arg75-Cys mutation in the COL2A1 gene, as well as the other families with the same mutation (5, 8). This prompted us to search for the same COL2A1 mutation in our patients, and the same mutation was detected. This phenotype has now been seen in 13 patients belonging to 4 families sharing the identical molecular background.

In all these 4 families, the Arg75-Cys mutation in the COL2A1 gene appears to lead to early osteoarthritis, brachymetatarsia, flat vertebrae, and irregular end plates. In addition, some features were found less constantly: relatively tall stature, intraarticular calcifications, sensorineural hearing loss, brachymetacarpalia, severe Schmorl's nodes and kyphoscoliosis or femoral epiphyseal enlargement in 1 family only. The clinical findings are shown in Table 1.

Table 1. Clinical features of the patients with the Arg75-Cys mutation in the procollagen type II (COL2A1) gene*
 Williams, 1993 Reginato, 1994Bleasel, 1995Bleasel, 1996Present case
  • *

    + = abnormalities present; − = no abnormalities/absent or not mentioned; OA = osteoarthritis.

CountryChileFranceUSAFinland
Sex (proband)FMMF
Number of affected persons/DNA studied7/162/42/52/5
Age at first symptoms, years1215Teenage7
First diagnosisChronic juvenile arthritisRheumatoid arthritis
Height, cm150 (0 SD)183 (+1.8 SD)Average-above average177 (+2.1 SD)
Arm span, cm/arm span to height ratio146/normal185.5 / 1.05
Upper to lower segment ratio1.000.77 (−1 SD)
Face   Small mandible, retrognathia, high arched palate
Spine    
 Childhood    
  Chondrodysplasia+
  Severe Schmorl's nodes++
  Kyphosis+
 Adult or any age    
  Flat vertebrae++++
  Anterior wedging+
  Irregular end plates++++
Hip changes at childhood    
 Legg-Perthes
 Femoral epiphysial enlargement+
Hip changes at any age    
 Intraarticular calcifications+++
 OA+++
Other joints+++
Hip prosthesis at age, years3536 18
Brachymetacarpalia/brachymetatarsia+/+−/++/+−/+
EyesNormalNo myopia
Hearing lossNormalModerately deafSensorineural hearing loss

Some radiologic features in our proband, however, resembled more those reported in connection with some other COL2A1 mutations (Arg519-Cys). In fact, clinically our patient resembled very much the patient described by Mier et al (19) except for the very peculiar shortness of the third and fourth metatarsals. This apparently reflects the overlapping clinical picture of some of the features caused by different mutations in procollagen type II (COL2A1) (20).

The symptoms and signs of our patient appeared first in the weight-bearing joints, e.g., back, hips, and later in the knees. In the hips, the fragile cartilage crumbles and causes synovial irritation and excess of fluid, which resembles juvenile rheumatoid arthritis. The small pieces that have been broken away from the cartilage begin to calcify intraarticularly and they can be seen in radiographs. The irregular spinal ossification resembles Scheuermann's deformity, which is a process that causes excess thoracic kyphosis and usually sclerosis. It is seen during adolescence, but seldom before the age of 11 years (16). The etiology of Scheuermann's disease is debatable. It has been thought to be multifactorial, but one thing that predisposes to it is thought to be the variability in the cartilage structure of the vertebral corpus and end plates after trauma or unusual stress of childhood. The mutant collagen chains containing cysteine exhibit abnormal biochemical properties. The cysteine residue might conceivably serve as a covalent trap of matrix protein that associates with the surface of collagen fibrils, resulting in altered fibril formation and premature failure of cartilage in patients with the mutation (10).

Neither the position of the mutation along the COL2A1 or the amino acid substitution is a consistent predictor of the severity of type II collagenopathies. R365C is described in patients with sporadic Stickler syndrome, R704C in Stickler syndrome type I with conductive hearing loss and eye problems but with mild skeletal changes (19). In exon 41 an Arg789-Cys mutation produces achondrogenesis type II (9). Certain joint manifestations appear to be nonspecific, although some features seem to cluster with specific mutations, such as brachydactyly and osteochondromata with the Arg75-Cys mutation and the absence of epiphyseal changes in the Arg519-Cys mutation (10). One specific feature of the Arg75-Cys mutation is hearing loss (Table 1).

Our findings add to the body of knowledge of the phenotype of the syndrome caused by an Arg75-Cys mutation in the COL2A1 gene. Because we had the opportunity to follow the proband's radiologic changes from childhood, the abnormal ossification in the vertebral bodies is obviously similar to that seen in Scheuermann's disease, but more severe. The different mutations in the COL2A1 gene have to be taken into account in the differential diagnosis when Scheuermann's disease and juvenile rheumatoid arthritis are suspected, especially if there is premature osteoarthritis and sensorineural hearing loss in the family.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

We would like to thank the family for their participation. We would also like to thank Mrs. Liisa Kärki from the Photolaboratory of Oulu University for preparing the photographs and illustrations.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
  • 1
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    Pun YL, Moskowitz RW, Lie S, Sundstrom WR, Block SR, McEwen C, et al. Clinical correlations of osteoarthritis associated with a single-base mutation (Arginine519 to Cysteine) in type II procollagen gene: a newly defined pathogenesis. Arthritis Rheum 1994; 37: 2649.
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    Williams CJ, Considine EL, Knowlton RG, Reginato A, Neumann G, Harrison D, et al. Spondyloepiphyseal dysplasia and precocious osteoarthritis in a family with an Arg75 – Cys mutation in procollagen type II gene (COL2A1). Hum Genet 1993; 92: 499505.
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    Williams CJ, Rock M, Considine E, McCarron S, Gow P, Ladda R, et al. Three new point mutations in type II procollagen (COL2A1) and identification of a fourth family with the COL2A1 Arg519-Cys base substitution using conformation sensitive gel electrophoresis. Hum Mol Genet 1995; 4: 30912.
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    Bleasel JF, Holderbaum D, Brancolini V, Moskowitz RW, Considine EL, Prockop DJ, et al. Five families with arginine519 – cysteine mutation in COL2A1: evidence for three distinct founders. Hum Mutat 1998; 12: 1726.
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    Reginato AJ, Passano GM, Neumann G, Falasca GF, Diaz-Valdez M, Jimenez SA, et al. Familial spondyloepiphyseal dysplasia tarda, brachydactyly, and precocious osteoarthritis associated with an arginine 75 [RIGHTWARDS ARROW] cysteine mutation in the procollagen type II gene in a kindred of Chiloe Islanders. I. Clinical, radiographic, and pathological findings. Arthritis Rheum 1994; 37: 107886.
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    Korkko J, Cohn DH, Ala-Kokko L, Krakow D, Prockop DJ. Widely distributed mutations in the COL2A1 gene produce achondrogenesis type II/hypochondrogenesis. Am J Med Genet 2000; 92: 95100.
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    Mier RJ, Holderbaum D, Ferguson R, Moskowitz R. Osteoarthritis in children associated with a mutation in the type II procollagen gene (COL2A1). Mol Genet Metab 2001; 74: 33841.
  • 20
    Knowlton RG, Katzenstein PL, Moskowitz RW, Weaver EJ, Malemud CJ, Pathria MN, et al. Genetic linkage of a polymorphism in the type II procollagen gene (Col2A1) to primary osteoarthritis associated with mild chondrodysplasia. N Engl J Med 1990; 311: 52630.