Inheritance of arterial lesions in renal fibromuscular dysplasia.

We have previously shown that patients with renal fibromuscular dysplasia (FMD) have asymptomatic carotid lesions and that familial forms may occur. The objective of this study was to test whether carotid lesions could be detected in relatives of familial cases. High-resolution echotracking of the carotid artery was performed in 47 relatives of 13 cases from six families. This non-invasive investigation led to a semiquantitative arterial score that was compared with that obtained for 47 controls matched for age and sex and that for 125 sporadic cases. Familial resemblance was tested by using a generalized estimating equation approach taking into account the clustering of scores in families. As expected, FMD cases had a significantly higher score than controls (4.02 vs 2.52, P<10(-5)). Familial cases were not significantly different from sporadic cases. Of interest, the 47 apparently healthy relatives of familial cases had also a high carotid score (4.17), very significantly higher than that of controls (2.52, P<10(-5)) even though lower than the corresponding index FMD cases (4.81, P=0.01). Segregation analysis showed that 52% of the descendants of subjects with a score >4 had a score >4, a proportion consistent with autosomal-dominant transmission of the trait. Altogether these results strengthen the hypothesis of renal FMD being a systemic arterial disease and argue for a familial resemblance that may be due to a major genetic effect. The carotid score obtained by high-resolution echotracking may provide a non-invasive surrogate marker for renal FMD of potential value for use in linkage strategies on large pedigrees.

Identification of novel polymorphisms in the pM5 and MRP1 (ABCC1) genes at locus 16p13.1 and exclusion of both genes as responsible for pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is an inherited systemic disorder of connective tissue, characterized by progressive calcification of the elastic fibers in the eye, the skin, and the cardiovascular system. The PXE locus has been mapped to chromosome 16p13.1, and was recently further refined to a 500 kb-region, containing four candidate genes : MRP1 (ABCC1), MRP6 (ABCC6), pM5, and two copies of an unknown gene, the later we subsequently found to be identical to the gene encoding the Nuclear Pore Interacting Protein (NPIP). In a comprehensive mutational screening, we have analysed the entire coding region of the pM5, MRP1, and NPIP genes in 7 patients affected with pseudoxanthoma elasticum, but failed to find evidence of disease-causing defects in any of these three genes. Five synonymous (G232G, P395P, A862A, G912G, D1106D), and five non synonymous (V404I, N458K, D490N, F1141I, G1195R) polymorphisms were found in the pM5 gene, for which we also corrected errors in the published cDNA sequence. Analysis of the MRP1 transcript lead to the discovery of two polymorphisms (T117M, S1512L). No variant was evidenced during our screening of the NPIP gene. Our data exclude the responsibility of the pM5, MRP1 and NPIP genes in PXE, and strongly suggest that mutations in the last remaining candidate gene, MRP6, which encodes a 1503 amino-acid ABC membrane transporter, are the genetic defect responsible for PXE.

[Mendelian arterial diseases. Pseudoxanthoma elasticum, Ehlers-Danlos vascular syndrome, Rendu-Osler disease]. / Maladies artérielles mendéliennes. Pseudoxanthome élastique, syndrome d'Ehlers-Danlos vasculaire, maladie de Rendu-Osler.

Understanding the features of the various hereditary vascular pathologies allows consideration and confirmation of the diagnosis, and a search for treatable hidden disorders, avoiding harmful investigations, initiating follow up, performing family investigations and providing genetic counselling. Pseudoxanthoma elasticum must be considered in the presence of calcified distal arteriopathy of the lower limbs in a young subject without any other aetiological aspects. Cutaneous or mucosal lesions confirmed on histological examination, angioid streaks at the back of the eye and a family history support the diagnosis, which is confirmed by showing pathogenic mutations of the ABCC6 gene. It is then important to search for a peripheral disorder in other arterial territory, a low grade coronaropathy, hypertension and an endocardial disorder. Prescription of antithrombotics must be made carefully because of the risk of gastro-intestinal haemorrhage. Vascular Ehlers-Danlos syndrome is suspected in a subject less than 30 years old with diffuse aneurysmal disease, spontaneous arterial rupture or dissection, a carotido-cavernous fistula or early onset varices. Demonstrating an ecchymotic tendency or an acrogeric morphology, especially in a familial context, warrants cutaneous biopsy for anatomopathological examination and fibroblast culture for a study of the C0L3A1 gene. When the diagnosis is suggested, it is advisable to prohibit any arterial puncture, cold surgery or gastro-intestinal endoscopy. The search for aneurysmal lesions must be performed by non-invasive imaging. The therapeutic management requires specialised teams. The combination of repeated epistaxis, muco-cutaneous telangectasia and similar characteristics in a family suggests the diagnosis of Osler-Weber-Rendu disease. The search for iron deficiency, gastro-intestinal bleeds and pulmonary, hepatic or cerebral arterio-venous malformations is then necessary. Besides skilled endovascular management when indicated, it is important to advise every patient with a pulmonary arterio-venous malformation to take antibiotic prophylaxis against cerebral abscess in situations at risk of bacteraemia.

[Subintimal angioplasty. Technique, results and role in the treatment of peripheral arterial occlusive disease]. / La recanalisation sous-intimale. Technique, résultats et place actuelle dans la stratégie de prise en charge de l'artériopathie des membres inférieurs.

Subintimal angioplasty consists in entering the subintimal space proximal to the occlusion, traversing the occlusion creating by angioplasty a subintimal channel exiting downstream in the natural lumen. Major complications rarely occur but compromising important collaterals or run-off vessels may be very deleterious. Subintimal angioplasty is indicated in patients with critical limb ischemia, unfit for anesthesia or in the absence of a suitable venous conduit. This technique is mainly effective in long and tibioperoneal occlusions, a location in which transluminal angioplasty usually fails. Further studies are required to determine the modalities of associated anti-thrombotic treatment and if subintimal angioplasty can be used as primary treatment in critical leg ischemia.

[The course of a case of Maffucci's syndrome]. / Evolution d'un cas de syndrome de Maffucci.

The syndrome of Maffucci is characterized by angioma association of the enchondromatose. It is a relatively rare syndrome. The lesions are evolutived. The treatment is surgical. His pronostic is marqued by high percentage of malign degenerescence.

[Microvascular involvement in pseudoxanthoma elasticum. Capillaroscopic findings]. / Microangiopathie du pseudoxanthome élastique. Aspects capillaroscopiques.

OBJECTIVE: The aim of this study was to describe, for the first time, the capillary angio-architecture during pseudoxanthoma elasticum, a rare genetic disease related to mutations in the ABCC6 gene, of which the systemic calcifying involvement is responsible notably for very severe cardiovascular complications. Method Seven patients suffering from clinically and histologically documented confirmed pseudoxanthoma elasticum were examined with capillaroscopy, the absence of concomitant connective tIssue disease or diabetes having been checked beforehand. RESULTS: All the patients exhibited a microangiopathy, characterised by normal capillary density, frequent pericapillary oedema, excessively coiled fibres with a significantly increased number of minor dystrophies and, to varying degrees, a slowing down of capillary blood flow demonstrated by a sludge phenomenon. CONCLUSION: This descriptive study shows that a microangiopathy exists during pseudoxanthoma elasticum. However, the latter is not specific and a double blind controlled study is required to confirm these results. The discovery of genotype/phenotype correlations in this disease would provide a place for capillaroscopy in the diagnostic strategy in young patients or in the assessment of the cardiovascular involvement.

Homozygosity for the R1268Q mutation in MRP6, the pseudoxanthoma elasticum gene, is not disease-causing.

Pseudoxanthoma elasticum (PXE) is an inherited systemic disorder of connective tissue, characterized by progressive calcification of the elastic fibers in the eye, the skin, and the cardiovascular system, resulting in decreased vision, skin lesions, and life-threatening vascular disease, with highly variable phenotypic expression. The PXE locus has been mapped to chromosome 16p13.1, and was recently further refined to a 500 kb-region, containing two pseudogenes and four candidate genes. In a comprehensive mutational screening, we were able to exclude the responsibility of pM5, UNK, and MRP1 genes, candidate on the basis of their genetic localization. Conversely, we have found pathogenetic mutations in the MRP6 gene, in patients affected with PXE, indicating that human MRP6, which encodes a 1503 amino-acids membrane protein, member of the human ATP binding cassette (ABC) transporters superfamily, is the gene responsible for PXE. In one large PXE pedigree for which we had identified a nonsense mutation (R1141X), we came across a G to A transition at position 3803 of the MRP6 cDNA sequence (R1268Q). Astonishingly, this latter variant was found at the homozygous state in the proband's unaffected husband. We investigated the R1268Q mutation, and found the Q1268 allele at a relatively high frequency (0.19) in a Caucasian control population (n = 62 subjects). Genotype frequencies were in Hardy-Weinberg equilibrium, and three healthy volunteers were homozygous for the Q1268 allele. These data indicate that the R1268Q variant in the MRP6 gene does not cause PXE per se. Further studies will elucidate if it may play a role when found in compound heterozygotes.