Rheumatology Advance Access originally published online on July 11, 2006
Rheumatology 2006 45(8):1052-1053; doi:10.1093/rheumatology/kel166
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LETTER TO THE EDITOR |
Spontaneous pneumothorax are seen in the joint hypermobility syndrome (JHS): reply
1 Department of Emergency Medicine, National Taiwan University Hospital, 2 Graduate Institute of Epidemiology, School of Public Health, National Taiwan University, 3 Department of Rehabilitation and Physical Medicine, Taipei Veteran General Hospital, 4 Graduate Institute of Preventive Medicine, School of Public Health, National Taiwan University and 5 Taipei City Hospital, Renai Branch, Taipei, Taiwan
Correspondence to: Chien-Chang Lee, MD, MSc, Department of Emergency Medicine, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan. E-mail: chnchnglee{at}yahoo.com
SIR, We thank Dr Bravo for his interest in our article. We agreed with his comment that Marfanoids with joint hypermobility syndrome (JHS) should be considered in patients with ankylosing spondylitis (AS) and spontaneous pneumothorax (SP). We re-evaluated our patients for the possibility of overlapping manifestations, but none of them were found to fulfill the Brighton criteria for the diagnosis of JHS. Except for arthralgia, we did not find other characteristic features of JHS such as multiple joint laxity, arachnodactily, thin transparent skin, blue sclerae, Gorlin's sign, varicose veins, rectal prolapse or hernia in our patients. One patient does show some features of Marfanoid habitus and joint hypermobility. He has a span/height ratio of 1.01 and a Beighton score of 2. Other two patients have a slender stature but do not have disproportionately long extremities or joint laxity. Features suggestive of type IV Ehlers–Danlos syndrome were also lacking in these three patients.
Primary SP is a common condition often affecting tall individuals with an asthenic habitus. Physical shape of the chest, especially a greater vertical-to-horizontal dimension ratio, has been suggested to play a major role in the development of SP, probably because of stress distribution in the lungs [1]. Both AS and Marfan's syndrome are characterized with such an elongated lung shape and associated with increased incidence of SP [2, 3]. In addition to Marfan's syndrome, Marfanoid habitus could be seen in many inheritable connective tissue disorders like Ehlers–Dalnos syndrome and JHS [4], which is also associated with increased incidence of SP. In addition to the mechanical stress theory, the inherited collagen defect of connective tissue disorders with Marfanoid habitus has been suggested to involve in the development of SP. The primary causative gene defect of JHS is unknown, and therefore the association between the collagen defect of JHS and SP remains elusive. However, the primary gene defect in Marfan's syndrome may offer some clue to the association between collagen defect and SP. The causal gene for Marfan's syndrome, FBN1, encodes the extracellular matrix glycoprotein fibrillin-1, which can be found in the lung as a component of elastic fibres. Defective fibrillin-1 was thus thought to contribute to the fragility of lung tissue. Besides, mice study showed that deficiency in fibrillin-1 causes marked dysregulation of transforming growth factor-ß, resulting in apoptosis in the developing lung [5]. Fibrillin-1 defect was also suggested to have a pathogenic role in AS [6], which may help explain the pulmonary pathology seen in AS. Despite the evidence, one recent study, however, failed to demonstrate linkage between FBN1 mutation and familial SP [7]. Therefore, whether SP in patients with Marfanoid habitus is the result of inherited collagen defect or undue mechanical stress on the apical lung tissue due to the elongated lung shape will continue to be an issue of debate in the future years. Further research is needed to better clarify the pathogenesis of SP in patients with connective tissue disease associated with an elongated lung shape such as Marfan's syndrome, JHS and AS.
The authors have declared no conflicts of interest.
References
- Peters RM, Peters BA, Benirschke SK, Friedman PJ. Chest dimensions in young adults with spontaneous pneumothorax. Ann Thorac Surg 1978;25:193–6.[Abstract]
- Hall JR, Pyeritz RE, Dudgeon DL, Haller JA,Jr. Pneumothorax in the Marfan syndrome: prevalence and therapy. Ann Thorac Surg 1984;37:500–4.[Abstract]
- Lee CC, Lee SH, Chang IJ et al. Spontaneous pneumothorax associated with ankylosing spondylitis. Rheumatology 2005;44:1538–41.
[Abstract/Free Full Text] - Bravo JF, Wolff C. Clinical study of hereditary disorders of connective tissues in a Chilean population: joint hypermobility syndrome and vascular Ehlers-Danlos syndrome. Arthritis Rheum 2006;54:515–23.[CrossRef][ISI][Medline]
- Neptune ER, Frischmeyer PA, Arking DE et al. Dysregulation of TGF-beta activation contributes to pathogenesis in Marfan syndrome. Nat Genet 2003;33:407–11.[CrossRef][ISI][Medline]
- Simkin PA. Acetabular osteitis in ankylosing spondylitis: does fibrillin figure in its pathogenesis?. J Rheumatol 2001;28:2663–6.[ISI][Medline]
- Cardy CM, Maskell NA, Handford PA et al. Familial spontaneous pneumothorax and FBN1 mutations. Am J Respir Crit Care Med 2004;169:1260–2.
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