Do pseudoxanthoma elasticum patients have higher prevalence of kidney stones on computed tomography compared to hospital controls?

BACKGROUND: Pseudoxanthoma elasticum (PXE) is an autosomal recessive disease characterized by diminished inorganic plasma pyrophosphate (PPi), a strong calcification inhibitor. In addition to more typical calcification of skin, retina and arterial wall a diminished plasma PPi could lead to other ectopic calcification, such as formation of kidney stones. OBJECTIVE: To compare the prevalence of kidney stones between PXE patients and hospital controls on computed tomography (CT). METHOD: Low-dose CT images of PXE patients and controls were assessed by one radiologist, who was blinded for the diagnosis PXE. The number of kidney stones, and the size of the largest stone was recorded. Odds ratios (ORs) for having kidney stone were calculated using multivariable adjusted logistic regression. RESULTS: Our study comprised 273 PXE patients and 125 controls. The mean age of PXE patients was 51.5 ± 15.9 years compared to 54.9 ± 14.2 in the control group (p = 0.04) and PXE patients more often were women (63 vs. 50%, p = 0.013). The prevalence of kidney stones on CT was similar: 6.9% in PXE patients, compared to 5.6% in controls (p = 0.6). In the multivariate analysis adjusting for age and sex, there was no significantly higher odds for PXE patients on having stones, compared to controls: OR 1.48 (95% CI 0.62-3.96). CONCLUSION: There is no significant difference in the prevalence of incidental kidney stones on CT in PXE patients versus controls.

Peripheral Interventions in Patients with Pseudoxanthoma Elasticum (PXE).

OBJECTIVE: Pseudoxanthoma elasticum (PXE) is an autosomal recessive metabolic disorder that may be associated with a high prevalence of peripheral artery disease (PAD) and related symptoms. However, the evidence supporting this association is weak, as only small cohort studies are available. Furthermore, limited data are available on the outcome of lower limb peripheral arterial interventions (PAI) in patients with PXE. It was the aim of this study to clarify the prevalence of PAD, and the occurrence and outcome of PAI in patients with PXE. METHODS: This was a retrospective review of prospectively collected data from the Dutch Expertise Centre for PXE database. Clinical data of consecutive patients with a definitive diagnosis of PXE were examined. The primary endpoint was the prevalence of PAD (defined as an ankle brachial index of < 0.9). The secondary endpoint was to report an overview of PAI and target lesion revascularisations. RESULTS: In 285 PXE patients (median age 58 years), 50.9% of patients (n = 145) met the criteria for PAD. Seventeen patients underwent a PAI, mostly for intermittent claudication, at a median age of 51 years. The incidence of PAI was 2.25 per 1 000 patient years in patients with PAD and PXE. A total of 58 interventions was recorded, of which 35 were target lesion revascularisations in nine patients. Twenty one revascularisations were performed within a year following the primary intervention, in 16 cases due to an acute occlusion. CONCLUSION: Within a well phenotyped and large PXE cohort, the diagnosis of PAD was prevalent in one in two patients. The observed rate of peripheral interventions was low, while the re-intervention rate was unfavourable after endovascular or bypass surgical procedures, with over half of these re-interventions indicated within a year.

Various vascular malformations are prevalent in Finnish pseudoxanthoma elasticum (PXE) patients: a national registry study.

BACKGROUND: Pseudoxanthoma elasticum (PXE, OMIM# 264800) is an inborn error of metabolism causing ectopic soft tissue calcification due to low plasma pyrophosphate concentration. We aimed to assess the prevalence of PXE in Finland and to characterize the Finnish PXE population. A nationwide registry search was performed to identify patients with ICD-10 code Q82.84. Information was gathered from available medical records which were requisitioned from hospitals and health centers. Misdiagnosed patients and patients with insufficient records were excluded. RESULTS: The prevalence of PXE in Finland was 1:260,000 with equal sex distribution. Patients with high conventional cardiovascular risk had more visual and vascular complications than patients with low risk. Four patients (19%) had at least one vascular malformation. A high proportion (33%) of ABCC6 genotypes were of the common homozygous c.3421C > T, p.Arg1141Ter variant. Nine other homozygous or compound heterozygous allelic variants were found. CONCLUSIONS: The prevalence of diagnosed PXE appears to be lower in Finland than in estimates from other countries. Decreased visual acuity is the most prevalent complication. We suggest that various vascular malformations may be an unrecognized feature of PXE.

Clinical and subclinical findings in heterozygous ABCC6 carriers: results from a Belgian cohort and clinical practice guidelines.

BACKGROUND: Biallelic pathogenic variants in the ATP-binding cassette subfamily C member 6 (ABCC6) gene cause pseudoxanthoma elasticum, a multisystemic ectopic calcification disorder, while heterozygous ABCC6 variants are associated with an increased risk of cardiovascular and cerebrovascular disease. As the prevalence of pathogenic ABCC6 variants in the general population is estimated at ~1%, identifying additional ABCC6-related (sub)clinical manifestations in heterozygous carriers is of the utmost importance to reduce this burden of disease. Here, we present a large Belgian cohort of heterozygous ABCC6 carriers with comprehensive clinical, biochemical and imaging data. Based on these results, we formulate clinical practice guidelines regarding screening, preventive measures and follow-up of ABCC6 carriers. METHODS: The phenotype of 56 individuals carrying heterozygous pathogenic ABCC6 variants was assessed using clinical (eg, detailed ophthalmological examinations), biochemical, imaging (eg, cardiovascular and abdominal ultrasound) and genetic data. Clinical practice guidelines were then drawn up. RESULTS: We found that ABCC6 heterozygosity is associated with distinct retinal alterations ('comet-like') (24%), high prevalence of hypercholesterolaemia (>75%) and diastolic dysfunction (33%), accelerated lower limb atherosclerosis and medial vascular disease, abdominal organ calcification (26%) and testicular microlithiasis (28%), though with highly variable expression. CONCLUSION: In this study, we delineated the multisystemic ABCC6 heterozygosity phenotype characterised by retinal alterations, aberrant lipid metabolism, diastolic dysfunction and increased vascular, abdominal and testicular calcifications. Our clinical practice guidelines aimed to improve early diagnosis, treatment and follow-up of ABCC6-related health problems.

The prevalence of pseudoxanthoma elasticum: Revised estimations based on genotyping in a high vascular risk cohort.

BACKGROUND: Pseudoxanthoma elasticum (PXE), an autosomal recessive systemic calcification disorder, is caused by mutations in the ABCC6-gene and associated with severe visual impairment and peripheral arterial disease. Given the progress in development of a therapy for PXE, more precise estimations of its prevalence are warranted. METHODS: We genotyped the four most common ABCC6 mutations (c.3421C > T, c.4182delG, c.3775delT, c.2787+1G > T), together accounting for half of all ABCC6 mutations identified in PXE patients from the Dutch population, in a Dutch high vascular risk cohort (n = 7893). The obtained allele frequencies were used to estimate the prevalence of PXE using the Hardy-Weinberg equilibrium. RESULTS: The carrier frequency of ABCC6 was 0.60% for c.3421C > T, 0.17% for c.4182delG, 0.05% for c.3775delT and 0.03% for c.2787+1G > T. The prevalence of PXE based upon the allele frequencies of these four mutations was estimated as 1 per 56,000 (95%CI 1 per 35,000-97,000). CONCLUSION: The prevalence of PXE is at least 1 per 56,000 meaning that there would be at least 307 affected individuals in the Netherlands that may benefit from a potential upcoming treatment. Since this estimate is based on mutations together accounting for half of all ABCC6 mutations identified among PXE patients, the actual prevalence will probably be higher.

[Study of fundus examination by age in 158 pseudoxanthoma elasticum patients]. / Étude du fond d'œil en fonction de l'âge dans le pseudoxanthome élastique chez 158 patients.

PURPOSE: To study the prevalence of fundus anomalies among patients with pseudoxanthoma elasticum as a function of their age. MATERIAL AND METHODS: All patients have had a complete ophthalmologic examination in multidisciplinary consultation for PXE in a national reference center. RESULTS: Hundred and fifty-eight patients (60 men and 98 women aged from 10 to 90 years old, mean 45±17 years) were included in a cross-sectional retrospective study. All fundus pictures were retrospectively reviewed over 9 years. Peau d'orange (55.6 %), was the first fundus feature observed in younger patients and disappeared with age. Angioid streaks (100 %), appeared during the second decade of life: at first hypofluorescent and then hyperfluorescent after 40 years old. Crystalline bodies (54.1 %), optic nerve head drusen (19 %) and peripheral pigmentation (39.9 %) were found in the various age groups. Macular atrophy (33.5 %) could have resulted from subretinal neovascularization (40.8 %), pattern dystrophies (7.9 %) or subretinal fibrosis (5.3 %). The onset of neovascularization appeared during the fourth decade. DISCUSSION: Progressive centrifugal calcification of Bruch's membrane is the cause of the many fundus features observed in PXE patients. CONCLUSION: Knowledge of the natural history of PXE can help the clinician explain and reassure patients about the evolving risks of ophthalmological involvement, particularly the fact that neovascular complications arise from the fourth decade.

Analysis of clinical symptoms and ABCC6 mutations in 76 Japanese patients with pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is a hereditary disease, causing calcification and degeneration of elastic fibers, which affects the skin, eye, cardiovascular systems and gastrointestinal tract. PXE is caused by mutations in the ABCC6 gene. Neither detailed nor large-scale analyses have been accomplished in Japanese patients with PXE. We, therefore, investigated clinical symptoms and ABCC6 gene mutations in 76 Japanese patients. Japanese PXE patients (n = 76) had a significantly lower incidence of vascular lesions than 505 PXE patients in the Leiden Open Variation Database (LOVD) (38.7% vs 65.1%, respectively; P = 1.34E-06); however, the incidences of the skin, eye, cardiac and gastrointestinal lesion symptoms were not significantly different. Symptom severity scores for skin, eye and vascular lesions, calculated using the Phenodex™ system, were significantly lower in Japanese PXE patients than in LOVD PXE patients. Genetic analysis revealed three nonsense, four frame-shift, one exon deletion and 13 missense mutations in ABCC6 in 73 patients; however, we were unable to detect pathogenic mutations in three patients. Frequent mutations differed between Japanese and LOVD PXE patients. In Japanese PXE patients, the top five mutations accounted for more than 60% of all pathogenic changes, suggesting the presence of founder effects. Consistent with previous reports, no obvious correlations between genotypes and phenotypes were identified in this study. In conclusion, we consider that the milder clinical phenotypes, observed even in older Japanese PXE patients, could be attributed to environmental factors such as dietary habits and lifestyle, as well as genetic background.

Cerebral disease in a nationwide Dutch pseudoxanthoma elasticum cohort with a systematic review of the literature.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is a monogenetic disease with progressive calcification of arteries and potential risk of stroke. To gain insights in the cerebral involvement in PXE, we evaluated prevalence and determinants of cerebral disease in our PXE cohort and performed a systematic review of literature. METHODS: Systematic history taking concerning cerebral disorders was performed in our PXE cohort. Cardiovascular risk factors were compared between PXE patients with and without cerebral disease. Additionally, Pubmed, Embase, the Cochrane Library and PsycINFO were systematically reviewed for studies published up to August 2016 about cerebral disease in PXE. RESULTS: Of the 178 PXE patients 31 (17%) had cerebral disease including ischemic stroke (n=15, 8%) or transient ischemic attack (n=13, 7%). The cerebral disease group was older (61±12 vs. 52±15years, adjusted p=0.004) and had less favorable profiles of traditional cardiovascular risk factors regarding the use of lipid lowering medication (61% vs. 31%, adjusted p=0.037) and levels of HDL-cholesterol (1.4±0.3 vs. 1.6±0.4mmol/L, adjusted p=0.005). One prospective cohort study reporting an incidence rate of ischemic stroke of 477/100,000/year and two cross-sectional studies with a reported prevalence of ischemic stroke of 14% and 0% were identified. Furthermore, 53 unique cases of cerebral disease in PXE including ischemic stroke (n=16) and transient ischemic attack (n=7) were reported. CONCLUSIONS: Physicians and patients should be aware of the prevalent occurrence of cerebrovascular disease in PXE, which further stresses the importance of strict cardiovascular risk management in these patients.

Mutation spectrum in the ABCC6 gene and genotype-phenotype correlations in a French cohort with pseudoxanthoma elasticum.

PURPOSE: Pseudoxanthoma elasticum (PXE) is an autosomal recessive disorder caused by variants in the ABCC6 gene. Ectopic mineralization of connective tissues leads to skin, eye, and cardiovascular manifestations with considerable phenotypic variability of unknown cause. We aimed to identify genotype-phenotype correlations in PXE. METHODS: A molecular analysis was performed on 458 French PXE probands clinically evaluated using the Phenodex score (PS). Variant topographic analysis and genotype-phenotype correlation analysis were performed according to the number and type of identified variants. RESULTS: Complete molecular analysis of 306 cases allowed the identification of 538 mutational events (88% detection rate) with 142 distinct variants, of which 66 were novel. Missense variant distribution was specific to some regions and residues of ABCC6. For the 220 cases with a complete PS, there was a higher prevalence of eye features in Caucasian patients (P = 0.03) and more severe eye and vascular phenotype in patients with loss-of-function variants (P = 0.02 and 0.05, respectively). Nephrolithiases and strokes, absent from the PS, were prevalent features of the disorder (11 and 10%, respectively). CONCLUSION: We propose an updated PS including renal and neurological features and adaptation of follow-up according to the genetic and ethnic status of PXE-affected patients.Genet Med advance online publication 19 January 2017.

Prevalence and severity of arterial calcifications in pseudoxanthoma elasticum (PXE) compared to hospital controls. Novel insights into the vascular phenotype of PXE.

BACKGROUND AND AIMS: Pseudoxanthoma elasticum (PXE) is a monogenetic disorder with progressive calcifications of the skin, the Bruch's membrane in the eyes and the arterial wall. Vascular disease is considered to be very prevalent, but the whole-body distribution of arterial calcifications in PXE is unknown. We aimed to systematically investigate arterial calcifications in PXE. METHODS: We included 104 PXE patients from the Dutch PXE cohort and 93 hospital controls. All subjects underwent full-body low-dose CT scans without contrast. To investigate the prevalence and severity of arterial calcification per arterial location, CT scans were scored using a reproducible semi-quantitative scale with four calcification categories (interobserver kappa 0.54-0.99). RESULTS: PXE patients (38/104 males) were 54 ± 13 years and controls (45/93 males) 54 ± 16 years old. Arterial calcifications were significantly more common in PXE patients in the intracranial internal carotid artery (75% vs. 44%), the arteries of the arms (20% vs. 3%), the femoral-popliteal arteries (74% vs. 44%) and the subpopliteal arteries (84% vs. 38%). In these arteries, calcification scores also indicated more severe calcification. No significant differences in prevalence of arterial calcification were observed in other arterial beds such as the coronary arteries (45% vs. 43%, p = 0.776), the carotid arteries (52% vs. 46%, p = 0.476) and the abdominal aorta (71% vs. 63%, p = 0.287). Analyses using patients younger than 55 years only, showed similar differences in prevalence of arterial calcifications between PXE patients and controls, with most pronounced calcifications in the arteries of the lower legs (67% vs. 8%). Similar patterns were observed in those without concomitant diabetes or renal dysfunction. CONCLUSIONS: In PXE, a vascular phenotype can be identified with a distribution of arterial calcifications that is clearly distinct from hospital controls and involves arterial calcifications in the legs, the intracranial internal carotid arteries and the arteries of the arms.

Increased vascular occlusion in patients with pseudoxanthoma elasticum.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is an autosomal recessive inherited multisystem disorder of the connective tissue caused by a loss-of-function mutation of the ABCC6 gene. It can affect the cardiovascular system, presumably leading to a high prevalence of atherosclerosis. PATIENTS AND METHODS: 46 PXE patients and 18 controls underwent an angiological examination consisting of measurement of ankle-brachial index (ABI), strain-gauge arterial reserve (SGAR), arterial resting perfusion, pulse wave index (PWI), central pulse wave velocity, and ultrasound examination. RESULTS: With an average age of 51.4 ± 12.4 years, 35/46 (76.1 %) of the PXE patients had atherosclerotic lesions, and 10 of them (28.6 %) had a chronic vascular occlusion of one or more peripheral vessels. 34/46 (73.9 %) had a pathologic ABI < 0.9, 15/42 (35.7 %) had a pathological SGAR < 10 mL/100 mL tissue/min, and 23/38 (60.5 %) had a pathological PWI > 180. The differences between the groups were statistically significant for ABI, arterial reserve, and PWI. CONCLUSIONS: In PXE patients atherosclerosis was found with a much higher prevalence than expected. Moreover, they were at very high risk for total vessel occlusions.
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Visual impairment in pseudoxanthoma elasticum: a survey of 53 patients from Turkey.

PURPOSE: To estimate the age at onset and severity of ophthalmologic aspects of pseudoxanthoma elasticum (PXE). METHODS: Medical records of 53 patients with PXE were evaluated. Findings at initial presentation, including refraction, best-corrected visual acuity (BCVA), and biomicroscopic and funduscopic examination were explored. RESULTS: The mean age of the patients at time of presentation was 43 years. The male-to-female ratio was 2.8:1. The mean age at occurrence of the first visual symptoms and retinal complications associated with choroidal neovascularization (CNV) was 42 years. Active subfoveal CNV or choroidal scar formation at the time of presentation was observed in 80 eyes (75%) of 49 patients (mean age 43 years). Twenty-seven patients (51%) (mean age 43 years) had BCVA ≤20/200 in at least one eye. Ten patients (19%) had BCVA ≤20/200 in both eyes (mean age 48 years). Twenty patients (41%) presenting with subfoveal chorioretinal scar or an active subfoveal CNV reported a spontaneous decline in visual acuity before age 40. CONCLUSIONS: Subfoveal CNV was a frequent finding responsible for the poor visual acuity of patients with PXE. Its formation was not strictly age-dependent, and in patients under 40 years of age could be underestimated. More trials are needed to determine clinical recommendations for follow-up of young patients with PXE.

The prevalence of pseudoxanthoma elasticum-like connective tissue changes in an oral biopsy service and review of the literature.

OBJECTIVE: The objective of this pilot study is to determine the prevalence of pseudoxanthoma elasticum (PXE)-like connective changes in an oral biopsy service and compare it with the estimated prevalence of PXE as well as to the prevalence of the mutated PXE gene ABCC6. STUDY DESIGN: This prevalence study utilized 500 oral mucosal biopsy specimens received from the biopsy service of the Oral Pathology Consultants at the Ohio State University. Each specimen was microscopically evaluated using hematoxylin and eosin, Verhoeff-van Gieson and von Kossa stains. RESULTS: A prevalence of 9.8% was identified for PXE-like changes in the connective tissue of oral biopsy specimens submitted to this service. CONCLUSIONS: The overall prevalence of PXE-like connective tissue changes found in routine oral mucosal biopsy specimens (9.8%) was much higher than either the suspected prevalence of PXE (0.001%-0.004%) or the estimated prevalence of the mutated gene ABCC6 (0.625%-1.25%).

Characterization of cardiovascular involvement in pseudoxanthoma elasticum families.

OBJECTIVE: Pseudoxanthoma elasticum (PXE) is an autosomal recessive connective tissue disorder with involvement of the skin, the retina, and the cardiovascular system. Cardiovascular involvement is mainly characterized by mineralization and fragmentation of elastic fibers of blood vessels and premature atherosclerosis. We conducted an ultrasound study to investigate the cardiovascular phenotype and to propose recommendations for the management of patients with PXE and heterozygous ABCC6 mutation carriers. APPROACH AND RESULTS: Thirty-two patients, 23 carriers, and 28 healthy volunteers underwent cardiac and vascular ultrasound studies. Cardiac imaging revealed left ventricular diastolic dysfunction in patients with PXE with a significantly prolonged deceleration time and lower septal early diastolic velocities of the mitral annulus compared with controls. Carriers also demonstrated significantly prolonged deceleration time. Carotid-to-femoral pulse wave velocity was significantly increased in patients with PXE when compared with carriers and controls. Vascular imaging revealed a high prevalence of peripheral artery disease in both patients and carriers and a significantly higher carotid intima-media thickness compared with controls. CONCLUSIONS: The results of this study clearly demonstrate impaired left ventricular diastolic function, impairment of the elastic properties of the aorta, and a high prevalence of peripheral artery disease in patients with PXE. Carriers also seem to exhibit a cardiovascular phenotype with mainly mild diastolic dysfunction and accelerated atherosclerosis. Increased awareness for cardiovascular events in both patients and heterozygous carriers is warranted.

[Myopia in pseudoxanthoma elasticum]. / Le pseudoxanthome élastique et la myopie.

INTRODUCTION: Refraction in patients with pseudoxanthoma elasticum (PXE) has not yet been studied in the literature. The purpose of our study was to determine if PXE may be associated with myopia, similarly to Marfan syndrome, another collagen-vascular disease. PATIENTS AND METHODS: This cross-sectional study evaluated 53 consecutive patients (32 women and 21 men, mean age 50 ± 16) from September 2009 to June 2011, with 53 age- and sex-matched controls. For each patient, we measured spherical equivalent, visual acuity, keratometry, axial length and crystalline lens power of each eye. Results were compared with Student's t-test. RESULTS: There was a significant difference between the mean values of myopia in the PXE population (-0.98) compared to the group of healthy controls (-0.33, P<0.0093). There was no significant difference between the two groups for the axial length (23.9 mm versus 23.69 mm; P=0.236), keratometry (43.53 versus 43.44; P=0.68), lens power (22.03 versus 21.71; P=0.225). DISCUSSION: PXE induces calcification of elastic fibers in various human tissues (skin, retina, vascular walls). Since there are no elastic fibers in the cornea or lens, we assume that the elastic zonular fibers may be pathologic in PXE patients. This could result in an anterior displacement of the lens in PXE, which could explain the moderate myopia. CONCLUSION: PXE may be associated with mild myopia compared to healthy controls. Additional studies, including more patients and evaluating anterior chamber depth and zonular histology are necessary to confirm these preliminary findings.

Pseudoxantoma elástico / Pseudoxanthoma elasticum

El pseudoxantoma elástico es una enfermedad hereditaria del tejido conectivo caracterizada por calcificación y fragmentación progresivas de las fibras elásticas en distintos tejidos. La prevalencia de la enfermedad se estima en 1 de cada 25,000 a 100,000 habitantes y es dos veces más frecuente en mujeres. Su diagnóstico precoz ayuda a prevenir las futuras complicaciones que estos pacientes pueden desarrollar (AU)

Pseudoxanthoma elasticum is a genetic disorder of the connective tissue characterised by progressive calcification and fragmentation of the elastic fibres in different body tissues. It has an estimated prevalence of 1 case in 25,000 to 100,000 population and is twice as common in women. Early diagnosis helps to prevent further complications these patients could develop (AU)

[Prevalence of involvement of the oral mucosa and periodontal tissue in pseudoxanthoma elasticum]. / Prévalence des atteintes de la muqueuse orale et du parodonte au cours du pseudoxanthome élastique.

INTRODUCTION: The prevalence and distribution of involvement of the oral and periodontal mucosa in pseudoxanthoma elasticum are not known. PATIENTS AND METHODS: Eighteen consecutive patients with pseudoxanthoma elasticum underwent routine stomatological examination and panoramic dental X-ray. RESULTS: Mucosal involvement was seen in 15 cases (83%): in nine cases it was limited to the inside of the lower lip and in six cases it also extended to the hard palate or soft palate, and/or the inside of the upper lip. Clinical examination showed the additional presence of active periodontal disease in four cases. The radiological examination revealed periodontal lysis in nine subjects and this disease was clinically active in three cases. DISCUSSION: Clinical involvement of the oral mucosa is extremely common in pseudoxanthoma elasticum, particularly on the inside of the lower lip. Oral lesions may provide diagnostic clues for pseudoxanthoma elasticum when skin lesions are either atypical or absent. The frequency of periodontal involvement in this preliminary study without control subjects did not appear to be higher than that seen in the general population.