Bone marrow failure in hypertrophic osteoarthropathy

Mutations in the SLCO2A1 gene and primary hypertrophic osteoarthropathy: a clinical and biochemical characterization

CONTEXT

We previously demonstrated that deficiency of the prostaglandin transporter (SLCO2A1) is a cause of primary hypertrophic osteoarthropathy (PHO). However, its clinical and metabolic characteristics have not been well defined.

OBJECTIVE

The objective of the study was to expand this mutational spectrum to better delineate the SLCO2A1 deficiency phenotype and investigate the clinical and metabolic characteristics of a cohort of subjects with PHO.

DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURE

Eleven affected individuals and their available healthy family members from 9 unrelated Chinese families with PHO (7 of which were previously undescribed) were clinically studied. The SLCO2A1 gene was screened and analyzed. Urinary levels of prostaglandin E₂ (PGE₂) and prostaglandin E metabolite (PGE-M) were measured using competitive ELISAs. The serum levels of total T, estradiol, sex hormone-binding protein, LH, FSH, and fasting gastrin were detected.

RESULTS

Nine different SLCO2A1 mutations were identified in affected individuals in the 7 previously undescribed families, 7 of which (Glu165X, Ala286GlnfsX35, Gln356AlafsX77, Gly369Asp, Gly379Glu, Glu465Lys, and c.861+2T>C) were novel. The urinary levels of PGE₂ and PGE-M were much higher in the SLCO2A1-deficient individuals and decreased with age. There was no relationship between sex hormones and PGE₂ or PGE-M. There was no significant difference in the levels of fasting serum gastrin between PHO patients with watery diarrhea and their relatives.

CONCLUSIONS

The present findings broaden the allelic spectrum of SLCO2A1 mutations. The urinary levels of PGE₂ and PGE-M in the SLCO2A1-deficient individuals decreased with age. The measurement of the excreted PGE₂ and PGE-M may have implications in the differential diagnosis, treatment, and follow-up of PHO.

Hypertrophic osteoarthropathy: a palindrome with a pathogenic connotation

PURPOSE OF REVIEW

The review seeks to update advances on the pathogenesis of hypertrophic osteoarthropathy, describe a previously unrecognized palindrome that occurs in hypertrophic osteoarthropathy and that may have pathogenic implications, and review the role of bisphosphonates in the treatment of this condition.

RECENT FINDINGS

Some patients with primary hypertrophic osteoarthropathy display an interesting palindrome. Many years after the onset of the osteoarthropathy, they develop diseases that in other circumstances are known to generate secondary hypertrophic osteoarthropathy. This palindrome has been reported in cases of patent ductus arteriosus, Crohn's disease and myelofibrosis. Additionally, primary hypertrophic osteoarthropathy and POEMS syndrome share important clinical features. The many diseases associated with hypertrophic osteoarthropathy have in common abnormal production of vascular endothelial growth factor. This cytokine has been proposed to play a major role in the pathogenesis of Crohn's disease, myelofibrosis and POEMS syndrome. A controlled study showed that vascular endothelial growth factor is abnormally expressed in cases of hypertrophic osteoarthropathy. The biologic effects of vascular endothelial growth factor may explain hypertrophic osteoarthropathy histological features. Several isolated reports suggest that pamidronate is effective in relieving painful osteoarthropathy.

SUMMARY

Hypertrophic osteoarthropathy is a palindromic syndrome. Anomalous vascular endothelial growth factor expression may explain this phenomenon. Bisphosphonates may have a role in the symptomatic treatment of hypertrophic osteoarthropathy.

Myelofibrosis in a patient with pachydermoperiostosis

Pachydermoperiostosis (idiopathic or primary hypertrophic osteoarthropathy) is a rare condition of unknown origin involving the skin and the skeleton, with an autosomal dominant transmission. We report a case of anaemia in a patient with pachydermoperiostosis indicating myelofibrosis, and review the literature and the pathogenetic mechanisms.

Pachydermoperiostosis: an update

Pachydermoperiostosis (PDP) is a rare genodermatosis, characterized by pachydermia, digital clubbing, periostosis and an excess of affected males. Although an autosomal dominant model with incomplete penetrance and variable expression has been proved, both autosomal recessive and X-linked inheritance have been suggested. However, at present, genetic heterogeneity is not fully supported. The aim of this study is to review the clinical and pedigree data of 68 published PDP families, including 204 patients. This analysis has confirmed an autosomal dominant mutation in 37 families and suggested the existence of an autosomal recessive form in the remaining families. The two forms may differ in clinical severity, intrafamilial variability and prevalence of some features. Additionally, the marked skewed sex ratio could not be easily explained by an X-linked mutation, but alternative explanations (i.e. testosterone promoting proliferation) are discussed.

Primary hypertrophic osteoarthropathy

We describe seven patients with primary HOA and review 125 cases reported in the English, French, and German literature. The salient clinical features of primary HOA are: a bimodal distribution of disease onset with one peak during the first year of life and the other at age 15, a male predominance (nine to one), uncommon benign joint effusion, and a variety of skin abnormalities resulting from cutaneous hypertrophy or glandular dysfunction. We concluded that HOA is not a synovial disease. It is suggested that synovial effusions, when present, are perhaps a sympathetic reaction to the neighboring periostitis. Proposed diagnostic criteria for HOA, including digital clubbing and radiographic periostitis, appear 86% sensitive. The clinical features, age of onset, and sex distribution suggest that a genetically controlled growth promoting factor, different from growth hormone, plays a role in the pathogenesis of this syndrome.