Fabry disease: a review.

Fabry disease is an inherited deficiency of the lysosomal hydrolase alpha-galactosidase A (alpha GalA) due to mutations in the Gal gene at Xq22. The result is intralysosomal accumulation of glycosphingolipids. In males who carry the mutation (1/40,000), severe multisystem disease develops in childhood or adolescence. Attacks of acute pain lasting a few minutes to a few days occur in the hands and feet, joints, muscles, and abdomen, sometimes with a fever. Highly suggestive skin lesions called angiokeratomas develop, as well as cornea verticillata characterized by corneal deposits without visual impairment. Stroke, seizures, heart disorders (conduction disturbances, valve disease, and left heart failure) and kidney disorders (proteinuria and chronic renal failure) develop in the third or fourth decade of life. Women who are heterozygous for the Gal gene can transmit the disease to their sons but are usually free of symptoms, although many have cornea verticillata. However, they may have moderate or severe disease related to uneven chromosome X inactivation. Late-onset variants with predominant neurological, cardiac, or renal manifestations have been described. The diagnosis is difficult when the family history is negative for Fabry disease. Tests on plasma and leukocytes show very low levels of alpha GalA activity in affected men, confirming the diagnosis. The Gal gene mutation should be looked for to detect heterozygous women. Symptomatic treatments include analgesics, antihypertensives, antiplatelet agents or anticoagulants to treat ischemic events, and hemodialysis or kidney transplantation to treat chronic renal failure. The recent introduction of enzyme replacement therapy with recombinant agalsidase alpha or beta has been a major breakthrough in the treatment of Fabry disease. Enzyme replacement therapy relieves the pain and decreases the risk of complications. The safety profile is good. Given the high cost of agalsidase therapy (about 160,000 euro/year/patient) and the low incidence of Fabry disease, patients should be referred to highly specialized centers (see addresses on the France Orphanet web site).

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS): definition, semiology, prognosis, pathogenesis, treatment, and place relative to other periodic joint diseases.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is an autosomal dominant inherited condition of periodic fever and pain. Most patients are of northern European descent. The attacks manifest as fever and pain in the joints, abdomen, muscles, skin, or eyes, with variations across patients. An acute-phase response occurs during the attacks. Patients with TRAPS are at risk for AA amyloidosis, the most common targets being the kidneys and liver. Soluble TNFRSF1A is usually low between the attacks and may be normal during the attacks, when TNF levels are high. TNFRSF1A is found in abnormally high numbers on leukocyte cell membranes. TRAPS is the first condition for which naturally occurring mutations in a TNF receptor were found; the mutations affect the soluble TNFRSF1A gene in the 12p13 region. In some patients, the pathogenesis involves defective TNFRSF1A shedding from cell membranes in response to a given stimulus. Thus, TRAPS is a model for a novel pathogenic concept characterized by failure to shed a cytokine receptor. This review compares TRAPS to other inherited periodic febrile conditions, namely, familial Mediterranean fever, Muckle-Wells syndrome, cold urticaria, and hyper-IgD syndrome. The place of TRAPS relative to other intermittent systemic joint diseases is discussed. Colchicine neither relieves nor prevents the attacks, whereas oral glucocorticoid therapy is effective when used in dosages greater than 20 mg/day. The pathogenic hypothesis involving defective TNFRSF1A shedding suggests that medications targeting TNF may be effective in TRAPS.

[Bone metabolism in men]. / Physiologie du tissu osseux chez l'homme.

The aim of this paper is to review the main physiologic features of bone metabolism in male. A brief description of bony cells and function is given. Hormonal influences on bone biology are described. Although androgens have been considered as essential in the regulation of bone metabolism in men, recent data have emphasised the fact that estrogens could play a dominant role.

A case of severe osteomalacia secondary to phosphate diabetes in a renal transplant recipient.

Transient hypophosphatemia is frequently observed during the first months after renal transplantation and is usually asymptomatic. Phosphate diabetes is defined as inadequate tubular phosphorus reabsorption leading to persistent renal phosphorus wasting, which is an important but overlooked cause of osteodystrophy in the post-renal transplantation population. We report the case of a 58-year-old male who presented with severe multiple osteoarticular pains within 3 months after successful first kidney transplantation. Bone disease was attributed initially to mild hyperparathyroidism secondary to vitamin D deficiency. Despite the correction of the hyperparathyroidism, the withdrawal of corticosteroids, and the reduction of immunosuppressive treatment to tacrolimus-based monotherapy, the osteoarticular pains persisted. Skeletal investigations at month 9 post-transplantation demonstrated a significant bone mineral density loss associated with osteomalacia and osteoporosis on the bone biopsy. Laboratory data showed persistent hypophosphatemia, and phosphate diabetes was then diagnosed explaining the post-transplant bone disease. A tacrolimus-induced renal tubular disorder was suspected to contribute to the excessive renal phosphorus wasting. The replacement of tacrolimus by sirolimus, in addition to oral phosphorus and vitamin D supplementations, led to the disappearance of pains, the normalization of urinary and plasma phosphate level, and a significant improvement of bone mineralization.