Elastic tissue abnormalities resembling pseudoxanthoma elasticum in beta thalassemia and the sickling syndromes

N-terminal natriuretic peptide and ventilation-perfusion lung scan in sickle cell disease and thalassemia patients with pulmonary hypertension

The aim of this study was to determine the prevalence of pulmonary hypertension (PH) in sickle cell disease and thalassemia patients in relation to clinical and laboratory parameters of hemolysis and hemosidersosis, as well as plasma N-terminal pro-brain natriuretic peptide (NT-pro-BNP). The study also aimed to define the role of thromboembolic pulmonary artery (PA) obstruction in its etiology. Forty sickle cell disease and 30 thalassemia patients [15 beta-thalassemia major (beta-TM) and 15 beta-thalassemia intermedia (beta-TI)] were screened for PH defined as tricuspid regurgitant velocity (TRV) >2.5 m/sec and evaluated for PA obstruction using ventilation-perfusion lung scan (V/Q), together with measurement of their plasma levels of NT-pro-BNP. Patients were prospectively followed up for a mean of 18 +/- 6.1 months. The prevalence of PH was 37.5, 40.0 and 26.7% in sickle cell disease, beta-TI and beta-TM patients, respectively. Pulmonary hypertension patients were older, had longer disease duration, higher serum ferritin, serum lactate dehydrogenase (LDH) and NT-pro-BNP with lower hemoglobin (Hb) levels compared to patients without PH. N-terminal pro-BNP was positively correlated with duration of illness, TRV, LDH, serum ferritin, and negatively correlated with Hb levels. The strongest predictor for TRV was serum ferritin followed by the NT-pro-BNP level. Forty-six-point-seven percent of sickle cell disease patients with PH had either high or intermediate probability V/Q scan results compared to 10% of thalassemic patients with PH who had high probability V/Q scan results. Pulmonary hypertension is highly prevalent in young sickle cell disease and thalassemia patients, where elevated serum ferritin and NT-pro-BNP are the main indicators.

Skin diseases in patients with beta-thalassemia major

BACKGROUND

Beta-thalassemia major affects multiple organs and is associated with considerable morbidity and mortality. The goal of this analysis was to document the frequency of skin diseases among patients with beta-thalassemia major.

METHODS

A sample of 78 patients with beta-thalassemia major was recruited and interviewed at the thalassemia clinic between April and June 2008. A dermatologist completed a skin examination of each patient and recorded any skin disease present. The patients' laboratory results and treatment modalities were recorded from the charts.

RESULTS

Sixty-five (83.3%) of the 78 patients examined had a diagnosed skin disease: pruritus (37.2%), xerosis (34.6%), scars (24.4%), ephelides (23.1%), skin irritation/erythema caused by deferoxamine pump (12.8%), idiopathic guttate hypomelanosis (6.4%), pityriasis alba (6.4%), tinea infections (5.1%), verruca vulgaris (5.1%), urticaria (3.8%), hyperhidrosis, contact dermatitis, and acne (2.6%), necrobiosis lipoidica (1.3%), melasma (1.3%), and others (14.1%). Pruritus and xerosis increased in frequency with age. The mean serum ferritin level was higher in patients with xerosis than in those without (5607.7 +/- 2997.5 ng/mL and 4285.2 +/- 4732.4 ng/mL, respectively) (P1/4 0.005). Moreover, xerosis was observed significantly more frequently inpatients using deferoxamine and deferiprone than in those using deferasirox (P1/4 0.047, P1/4 0.027, and P1/4 0.273, respectively).

CONCLUSION

Skin diseases, especially pruritus and xerosis, are observed highly frequently inpatients with beta-thalassemia major. Treatment is needed for these patients who already have other significant morbidities.

Magnetic resonance imaging evaluation of mandibular condyle bone marrow and temporomandibular joint disc signal intensity in anaemia patients

OBJECTIVES

To compare the signal intensity (SI) of mandibular condyle bone marrow (MCBM) and the temporomandibular joint (TMJ) disc in patients with chronic anaemia and healthy subjects, and to investigate the relationships between bone marrow changes, age, types of anaemia and severity of anaemia.

METHODS

MRIs of 18 patients with chronic anaemia were compared with those of 12 healthy subjects. The SI of MCBM and the TMJ disc were quantitatively evaluated. The SI of the grey matter (GM), white matter (WM) and the lateral pterygoid muscle were also investigated. Relationships between age, MCBM and TMJ disc signal-intensities and anaemia severity, and correlations between the groups, were analysed.

RESULTS

The mean MCBM SI was lower in anaemia patients (including both subgroups and also separately) than in healthy subjects (P < 0.05). No statistical significance was found for GM, WM and the muscle SI between the anaemia patients and healthy patient group (P > 0.05). No statistical significance was found between the groups with respect to the anterior band, whereas the mean SI value of the posterior band in the study group was significantly lower than in healthy subjects (P < 0.05). There were no correlations between age and MCBM SI, or between anaemia severity and MCBM SI.

CONCLUSIONS

Anaemia may cause bone marrow alterations without any internal derangement. Patients with chronic anaemia exhibit lower mandibular condyle bone marrow and posterior band SI than healthy subjects.

Comparison of vascular complications between conventional treatment and bone marrow transplantation for children with beta-thalassemia disease

Patients with ss-thalassemia may be predisposed to premature atherosclerosis due to vascular dysfunction. This is observed in adults. Whether atherosclerosis changes in ss-thalassemia disease (BTD) occur early in childhood is not clear. To prevent cardiovascular complications, this needs evaluation. Moreover, it remains uncertain whether curative treatment with bone marrow transplantation (BMT) would improve this vascular alteration. For this study, 37 ss-thalassemia children age 10.1 +/- 2.7 years were classified into group 1 (25 children with BTD treated conventionally) and group 2 (12 children with BTD who underwent BMT). A control group of 29 age-matched healthy children were studied simultaneously. The carotid stiffness index and intima-media thickness (IMT) were measured. Group1 had a greater arterial stiffness index than the control subjects (4.57 +/- 1.78 vs. 2.87 +/- 1.07; p < 0.001). The carotid IMT was significantly greater in both BTD groups than in the control group (group 1: 0.45 +/- 0.03 vs. 0.34 +/- 0.04 mm; p < 0.001; group 2: 0.43 +/- 0.03 vs. 0.34 +/- 0.04 mm; p < 0.001). Carotid IMT and arterial stiffness are increased in conventionally treated children with ss-thalassemia, suggesting an early atherosclerotic change in these children, whereas children with BTD who underwent BMT had an increased carotid IMT but normal arterial stiffness.

Cardiac function and iron chelation in thalassemia major and intermedia: a review of the underlying pathophysiology and approach to chelation management

Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia. The two main factors that determine cardiac disease in homozygous β thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload. The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype. Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function. For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy. Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients. If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted. In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available. With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with increasing the transfusions as need, it is hoped that the incidence of cardiac dysfunction in these syndromes will be markedly reduced. This of course depends very much on the attention to detail with the monitoring and the cooperation of the patient with both the recommended investigations and the prescribed chelation.

Pseudoxanthoma elasticum: genetics, clinical manifestations and therapeutic approaches

Pseudoxanthoma elasticum (PXE) is an inherited disorder that is associated with accumulation of mineralized and fragmented elastic fibers in the skin, vascular walls, and Bruch's membrane in the eye. Clinically, patients exhibit characteristic lesions of the posterior segment of the eye including peau d'orange, angioid streaks, and choroidal neovascularisations, of the skin including soft, ivory-colored papules in a reticular pattern that predominantly affect the neck and large flexor surfaces, and of the cardiovascular system with peripheral and coronary arterial occlusive disease as well as gastrointestinal bleedings. There is yet no definitive therapy. Recent studies suggest that PXE is inherited almost exclusively as an autosomal recessive trait. Its prevalence has been estimated to be 1:25,000-100,000. Very recently, the ABCC6 gene on chromosome 16p13.1 was found to be associated with the disease. Mutations within ABCC6 cause reduced or absent transmembraneous transport that leads to accumulation of extracellular material. Presumably, this mechanism causes calcification of elastic fibers. Despite the characteristic clinical features, the variability in phenotypic expressions, and the low prevalence may be responsible for the disease being underdiagnosed. This review compiles and summarizes current knowledge of PXE pathogenesis and clinical findings. Furthermore, different therapeutic strategies to treat retinal manifestations are discussed, including thermal laser coagulation, photodynamic therapy, and intravitreal injections of drugs inhibiting vascular endothelial growth factor.

Angioid streaks in thalassemia intermedia: warning for thromboembolic events

PURPOSE

Pseudoxanthoma elasticum-like lesions have been described in association with an increased risk for stroke in β-thalassemia. We describe a patient with thalassemia intermedia and angioid streaks who developed a central retinal artery occlusion and subsequent portal vein thrombosis.

METHOD AND PATIENT

Case report of a 47-year-old woman with thalassemia intermedia, angioid streaks, central retinal artery occlusion, and portal vein thrombosis.

RESULTS

Our patient presented with a cilioretinal artery-sparing central retinal artery occlusion in the left eye and evidence of angioid streaks in both eyes. One month later, she developed neovascularization of the angle in the left eye and underwent panretinal photocoagulation. Neovascularization of the angle resolved, and final vision was 20/30. She later developed portal vein thrombosis, and anticoagulation was started.

CONCLUSION

The finding of angioid streaks in the setting of thalassemia may suggest the presence of a systemically defective elastin layer. This can be a procoagulative factor and may warrant further assessment of the coagulation and cardiovascular system to take prophylactic measures. The occurrence of a thromboembolic event, however, is multifactorial and the end result of interaction of procoagulant and anticoagulant factors.

Cardiac involvement in sickle beta-thalassemia

Cardiovascular involvement is a leading cause of mortality and morbidity in patients with inherited hemoglobinopathies, but it has not been adequately assessed in sickle beta-thalassemia. We evaluated 115 sickle beta-thalassemia patients, aged 34 +/- 14 years, along with 50 healthy controls, by resting echocardiography. Patients with systolic left ventricular (LV) dysfunction or severe pulmonary hypertension (PHT) also underwent left and right cardiac catheterization and cardiac magnetic resonance imaging (CMR). Left and right chamber dimensions, LV mass, and cardiac index were significantly higher in patients compared to controls (p < 0.001 in most cases). Three patients (2.9%) had reduced LV ejection fraction (<55%); mean LV ejection fraction was significantly lower in patients (p < 0.001). Left and right ventricular systolic tissue Doppler indices and LV diastolic tissue Doppler indices were also impaired in patients. All three patients with systolic LV dysfunction had normal coronary arteries and mild myocardial iron load (CMR T2* values, 18-25 ms). Systolic pulmonary artery pressure was significantly higher in patients compared to controls (p = 0.002); PHT was present in 28 patients (27%), while severe PHT in three (2.9%). In three patients with severe PHT, only one had impaired LV ejection fraction and increased pulmonary wedge pressure. Overall, three patients (2.9%) had a history of heart failure, two with systolic LV dysfunction, and one with severe PHT. Cardiac involvement in sickle beta-thalassemia concerns biventricular dilatation and dysfunction along with PHT, leading to congestive heart failure.

Parameters of oxidative stress are present in the circulation of PXE patients

Pseudoxanthoma elasticum (PXE) is an inherited disorder characterized by calcification of elastic fibres leading to dermatological and vascular alterations associated to premature aged features and to life threatening clinical manifestations. The severity of the disease is independent from the type of mutation in the ABCC6 gene, and it has been suggested that local and/or systemic factors may contribute to the occurrence of clinical phenotype. The redox balance in the circulation of 27 PXE patients and of 50 healthy subjects of comparable age was evaluated by measuring the advanced oxidation protein products (AOPP), the lipid peroxidation derivatives (LOOH), the circulating total antioxidant status (TAS), the thiol content and the extracellular superoxide dismutase activity (EC-SOD). Patients were diagnosed by clinical, ultrastructural and molecular findings. Compared to control subjects, PXE patients exhibited significantly lower antioxidant potential, namely circulating TAS and free thiol groups, and higher levels of parameters of oxidative damage, as LOOH and of AOPP, and of circulating EC-SOD activity. Interestingly, the ratio between oxidant and antioxidant parameters was significantly altered in PXE patients and related to various score indices. This study demonstrates, for the first time, that several parameters of oxidative stress are modified in the blood of PXE patients and that the redox balance is significantly altered compared to control subjects of comparable age. Therefore, in PXE patients the circulating impaired redox balance may contribute to the occurrence of several clinical manifestations in PXE patients, and/or to the severity of disease, thus opening new perspectives for their management.

Study of the eye and lacrimal glands in experimental iron overload in rats in vivo

A variety of syndromes leading to hemosiderosis in men cause ocular lesions. The purpose of the present study was to determine the distribution of iron and of transferrin in the eyes and lacrimal glands of rats in experimental hemosiderosis, so as to achieve a better understanding of the formation of the ocular lesions observed in patients with advanced hemosiderosis. In order to achieve hemosiderosis the rats were fed 3% (w/w) carbonyl iron or received i.p. or i.v. polymaltose iron. Hemosiderin deposits were detected in macrophages lying in the interlobular connective tissue of lacrimal glands, in the interstitial connective tissue of the choroid, in the ciliary body, in the iris and extracellularly in the sclera in all animals that received iron i.v. Also, scanty hemosiderin laden macrophages were found to a lesser degree in interstitial connective tissue of the choroid and in the interlobular connective tissue of lacrimal glands in animals that received iron i.p. No iron deposits were detected in the eye and lacrimal glands of control rats and in rats that were on an iron enriched diet. No transferrin was detected in the eye and in the lacrimal glands, neither in the control rats nor in the rats that received iron. Experimental iron overload leads to increased iron deposition in tissues of the eye and lacrimal glands, whereas no transferrin could be detected in the aforementioned organs.

Sickle cell disease vasculopathy: a state of nitric oxide resistance

Sickle cell disease (SCD) is a hereditary hemoglobinopathy characterized by microvascular vaso-occlusion with erythrocytes containing polymerized sickle (S) hemoglobin, erythrocyte hemolysis, vasculopathy, and both acute and chronic multiorgan injury. It is associated with steady state increases in plasma cell-free hemoglobin and overproduction of reactive oxygen species (ROS). Hereditary and acquired hemolytic conditions release into plasma hemoglobin and other erythrocyte components that scavenge endothelium-derived NO and metabolize its precursor arginine, impairing NO homeostasis. Overproduction of ROS, such as superoxide, by enzymatic (xanthine oxidase, NADPH oxidase, uncoupled eNOS) and nonenzymatic pathways (Fenton chemistry), promotes intravascular oxidant stress that can likewise disrupt NO homeostasis. The synergistic bioinactivation of NO by dioxygenation and oxidation reactions with cell-free plasma hemoglobin and ROS, respectively, is discussed as a mechanism for NO resistance in SCD vasculopathy. Human physiological and transgenic animal studies provide experimental evidence of cardiovascular and pulmonary resistance to NO donors and reduced NO bioavailability that is associated with vasoconstriction, decreased blood flow, platelet activation, increased endothelin-1 expression, and end-organ injury. Emerging epidemiological data now suggest that chronic intravascular hemolysis is associated with certain clinical complications: pulmonary hypertension, cutaneous leg ulcerations, priapism, and possibly stroke. New therapeutic strategies to limit intravascular hemolysis and ROS generation and increase NO bioavailability are discussed.

[Pseudoxanthoma elasticum-like syndrome associated with hemoglobinopathy: a case report]

INTRODUCTION

We report a case of hemoglobinopathy which could be associated with a pseudoxanthoma elastic-like syndrome.

EXEGESIS

We report the case of a 26-year-old male patient with sickle cell anemia for which the supra-aortic-doppler ultrasonography suggested an asymptomatic left carotid artery of 70% stenosis. The magnetic resonance imaging and angiography showed a left megadolichocarotid with plicature suggestive of pseudoxanthoma elastic or a dilatation relative to a high rate of blood explaining the acceleration speed. There was a cutaneous infiltration but other vasculopathies of neither carotide, nor cerebral, nor ocular have been discovered while they were sometimes found in pseudoxanthoma elastic-like syndrome. This acquired form is different of rare hereditary disease by a later diagnosis, a clinical expression often very incomplete and a frequent association with hemoglobinopathies.

CONCLUSION

This observation shows that RMA could be necessary to perform in adults, when cervical and transcranial Doppler ultrasonography is abnormal, particularly before deciding to start long term blood transfusions. The hemoglobinopathy and pseudoxanthoma elastic-like syndrome must not be ignored because the control of cardiovascular factors reduce the risks of arterial complications.

Loss of vision associated with angioid streaks in beta-thalassemia intermedia

An acquired diffuse elastic tissue defect that resembles inherited pseudoxanthoma elasticum (PXE) has been noticed with a significant age-related frequency in hemoglobin disorders, especially beta-thalassemia and has been held responsible for a number of complications observed in these cases, some of which are quite severe. We report here two patients with beta-thalassemia intermedia, who presented with severe visual acuity impairment associated with angioid streaks, the typical ocular manifestation of PXE.

The heart in transfusion dependent homozygous thalassaemia today--prediction, prevention and management

Cardiac disease remains the major cause of death in thalassaemia major. This review deals with the mechanisms involved in heart failure development, the peculiar clinical presentation of congestive heart failure and provides guidelines for diagnosis and management of the acute phase of cardiac failure. It emphasizes the need for intensive medical – cardiac care and aggressive iron chelating management as, with such approaches, today, the patients outcomes can be favourable in the long term. It covers advances in the assessment of cardiac iron overload with the use of magnetic resonance imaging and makes recommendations for preventing the onset of cardiac problems by tailoring iron chelation therapy appropriate to the degree of cardiac iron loading found.

Congenital dyserythropoietic anaemia, type I, in a Caucasian patient with retinal angioid streaks (homozygous Arg1042Trp mutation in codanin-1)

A congenital dyserythropoietic anaemia (CDA) was recognised in a French Caucasian male patient. Blood smears showed a pronounced aniso-poikilocytosis. Bone marrow light microscopy showed signs of dyserythropoesis, but no internuclear chromatin bridges. Electron microscopy disclosed erythroblast nuclei with the Swiss cheese aspect and the presence of cytoplasmic organelles, assessing the diagnosis of CDA I. The presence of internuclear chromatin bridges may thus be missing in CDA I. The patient proved to be homozygous for the Arg1042Trp mutation in codanin-1 (the 'Bedouin mutation'). By the age of 25, the patient's vision started to deteriorate as a result of retinal angioid streaks and macular abnormalities. Evolution was controlled and the patient, being nearly 50 yr old now, still has a partial use of his eyes. This second case of retinal angioid streaks reported in CDA I adds to the non-haematological features likely to be associated with this condition.

Thalassemia intermedia today: should patients regularly receive transfusions?

BACKGROUND

beta-Thalassemia is an inherited hemoglobin disorder characterized by reduced synthesis of beta-globin chain. The severity of clinical course distinguishes this heterogeneous disease in two main subtypes: thalassemia major (TM) and thalassemia intermedia (TI). TI has a later clinical onset with a milder anemia that does not require transfusions at least during the first few years of life. The clinical picture of TI patients who have not received transfusions or have occasionally received transfusions is dominated by the consequences of chronic hemolytic anemia, tissue hypoxia, and their compensatory reactions, such as bone deformities and fractures, extramedullary hemopoiesis, spleen and liver enlargement, hypercoagulability, and pulmonary hypertension. These complications, especially the latter two, are getting more frequent and severe over the years. Nowadays, although TI patients have almost no changes in the course of the disease, well-treated TM patients with regular transfusion-chelation therapy showed suppression of the anemia-related disorders in parallel to prolongation of life. The new oral iron chelators and the magnetic resonance imaging application for early detection of heart iron load are promising for further improvement on survival.

CONCLUSIONS

Considering the current cost-benefit balance of regular treatment in TM as well as the frequency and severity of complications in TI, it seems that the majority of TI patients will be benefited if this kind of treatment is applied targeting prevention and not palliation of the anemia-induced complications.

Stiffness of the abdominal aorta in beta-thalassemia major patients related with body iron load

OBJECTIVES

Increased iron stores have been implicated in the association with increased risk of cardiovascular events. We evaluated whether the abdominal aortic stiffness was altered in the patients with beta-thalassemia major in relation with body iron load.

METHODS

Sixty-two (32 males and 30 females) beta-thalassemia major patients aged 16.47 +/- 4.8 years were enrolled into the study. Healthy 52 subjects matched for age and sex were recruited as controls. In all subjects, hemoglobin, fasting glucose, cholesterol, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol levels were measured. The average serum ferritin level and liver iron concentration (LIC) were assessed in thalassemia patients. Left ventricular function and mass were evaluated echocardiographically and aortic strain (S), pressure strain elastic modulus (Ep), and normalized Ep (Ep*), aortic distensibility (DIS), and beta stiffness index (beta index) were calculated in all subjects.

RESULTS

There was no statistically significant difference between the study and control groups in sex, mean age, body mass index, heart rate, and systolic blood pressure (P > 0.05). However, pulse pressure and left ventricular mass index (LVMI) were found higher in thalassemia major patients compared with the control group. In beta-thalassemia major patients S (0.21 +/- 0.027 vs. 0.26 +/- 0.017, P < 0.0001) and DIS (1.07 +/- 0.25 vs. 1.56 +/- 0.37, P < 0.0001) were significantly lower compared with the control group. However, Ep (196.9 +/- 44.86 vs. 134.20 +/- 29.10, P < 0.0001), Ep* (3.26 +/- 0.98 vs. 2.04 +/- 0.60, P < 0.0001), and beta index (2.44 +/- 0.58 vs. 1.61 +/- 0.37, P < 0.0001) were significantly higher in beta-thalassemia patients than controls. There was a statistically significant negative correlation between LIC and S, DIS. There was also negative correlation between LVMI and S. However, there was a statistically significant positive correlation between LIC and Ep, Ep*.

CONCLUSIONS

Increased abdominal aortic stiffness was detected in beta-thalassemia major patients and this increase in arterial stiffness correlated with LIC and LVMI.

HNF4alpha and NF-E2 are key transcriptional regulators of the murine Abcc6 gene expression

Mutations in an ABC transporter gene called ABCC6 are responsible for pseudoxanthoma elasticum (PXE), a rare heritable disease characterized by elastic fiber calcification in skin, ocular and vascular tissues. The presumed function of this ABC transporter is to export metabolites from polarized cells. However, the endogenous substrate(s) are unknown and the exact relationship with elastic fibers is unclear. As ABCC6 is only expressed at high level in liver and kidneys, tissues seemingly unrelated to the PXE phenotype, we explored the transcriptional regulation of the murine Abcc6 gene to define the transcriptional signal conferring tissue specificity and to gather clues on its possible biological function. We cloned 2.9 kb of the mAbcc6 5'-flanking region and several deletion constructs linked to a luciferase reporter gene. We delineated a proximal promoter and a liver-specific enhancer region. We also demonstrated that the proximal region is a TATA-less promoter requiring an intact CCAAT-box and Sp1 binding for its basal activity. By using reporter assays and chromatin immunoprecipitations, we showed that HNF4alpha and surprisingly, NF-E2, enhanced the mAbcc6 promoter activity. The involvement of both HNF4alpha and NF-E2 in the mAbcc6 gene regulation suggests that Abcc6 might be involved in a detoxification processes related to hemoglobin or heme.

Augmentation de l’hémoglobine A2 au cours du pseudoxanthome élastique

BACKGROUND

Pseudoxanthoma elasticum (PXE) is normally associated with mutations in the ABCC6 gene. A PXE phenotype without mutations in ABCC6 has been described in Greek and Italian patients presenting with beta thalassemia. We attempted to determine the incidence of beta thalassemia in a cohort of French patients with PXE.

PATIENTS AND METHODS

Fifty patients with PXE were included in the study. Laboratory examinations comprised hemoglobin electrophoresis, ABCC6 gene study and in some studies: mutation analysis, beta-globin gene.

RESULTS

No cases of beta thalassemia were diagnosed in this cohort of French patients with PXE. However, 20% of the latter exhibited a significant but isolated (i.e. without microcytic anemia) increase of hemoglobin A2 (HbA2). Statistical comparisons showed no difference in terms of geographical origin or severity of PXE between patients with high levels of HbA2 and those with normal levels of HbA2 other than the extent of cutaneous involvement. Study of the beta-globin gene displayed mutations only in the two patients with the highest recorded levels of HbA2. ABCC6 + beta-globin digenism was ruled out of the pathogenesis of PXE.

DISCUSSION

The PXE phenotype seen in some patients with beta thalassemia appears to be associated with epigenetic modification of ABCC6 transcription and depends specifically on the beta globin locus. Isolated increase in HbA2 is probably a laboratory marker for PXE. Here again, a functional epigenetic reaction between ABCC6 and the beta-globin locus was suspected. However, these reciprocal interactions are clearly unequal since the change in ABCC6 transcription occurring during the course of beta thalassaemia is responsible for a PXE phenotype while increased HbA2 during the course of PXE has no clinical consequences.

Pulmonary hypertension in beta-thalassemia

Cardiac involvement represents the leading cause of mortality in both forms of beta-thalassemia, namely, thalassemia major (TM) and thalassemia intermedia (TI), and pulmonary hypertension (PHT) is part of the cardiopulmonary complications of the disease. PHT was initially documented in a small group of TI patients with right heart failure. In a subsequent study of a large 110-patient series, aged 32.5 +/- 11.4 years, age-related PHT was encountered in nearly 60% of cases, having caused right heart failure in six of them; interestingly, all patients had preserved left ventricular systolic function. Conflicted evidence, however, existed with respect to the development of PHT in heterogeneously treated and young TM populations. To resolve this discrepancy, a recent study compared cardiac disease between two large aged-matched groups of TM (n = 131) and TI (n = 74) patients, both treated uniformly in the currently accepted manner (regular transfusion and chelation therapy in TM, absence of any particular treatment in TI); well-treated TM patients, in contrast to TI patients, did not develop PHT, while systolic left ventricular dysfunction was present only in TM cases. PHT in beta-thalassemia results from a rather complex pathophysiology, in which chronic tissue hypoxia seems to hold a key role. Although both forms of the disease share a common molecular background, the diverse severity of the genetic defect and of the resulting clinical phenotype require a different therapeutic approach. Regular lifelong therapy in TM patients eliminates chronic hypoxia, thereby preventing PHT, whereas the absence of systematic treatment in TI leads to a cascade of reactions that compensate for chronic anemia, but at the same time allow the development of PHT.

Pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is an inherited disorder that is associated with accumulation of mineralized and fragmented elastic fibers in the skin, vessel walls, and Bruch's membrane. Clinically, patients exhibit characteristic lesions of the skin (soft, ivory-colored papules in a reticular pattern that predominantly affect the neck), the posterior segment of the eye (peau d'orange, angioid streaks, choroidal neovascularizations), and the cardiovascular system (peripheral arterial occlusive disease, coronary occlusion, gastrointestinal bleeding). There is no causal therapy. Recent studies suggest that PXE is inherited almost exclusively as an autosomal recessive trait. Its prevalence has been estimated to be 1:25,000-100,000. The ABCC6 gene on chromosome 16p13.1 is associated with the disease. Mutations within the ABCC6 gene cause reduced or absent transmembraneous transport that leads to accumulation of substrate and calcification of elastic fibers. Although based on clinical features the diagnosis appears readily possible, variability in phenotypic expressions and the low prevalence may be responsible that the disease is underdiagnosed. This review covers current knowledge of PXE and presents therapeutic approaches.

Endothelial function and arterial stiffness in sickle-thalassemia patients

BACKGROUND

Homozygous sickle-cell anemia and beta-thalassemia are characterized by impaired endothelial function, while data on arterial stiffness have hitherto been conflicting. We sought to investigate aortic elastic properties and endothelial function in sickle-thalassemia, which combines molecular and clinical features of the above conditions.

METHODS AND RESULTS

Forty-seven sickle-thalassemia patients, younger than 45 years, with preserved left ventricular (LV) function and no history of smoking, systemic or pulmonary hypertension, diabetes mellitus, dyslipidemia or thyroid disease, along with 40 healthy controls were studied. Aortic strain, distensibility and stiffness index were calculated by echocardiographically-obtained aortic root diameters. Brachial artery endothelial function was assessed by ultrasonographic evaluation of flow-mediated dilatation (FMD) and nitrate-mediated dilatation (NMD). Left ventricle was assessed by echocardiography. Patients had an impaired FMD (4.2+/-2.9% versus 9.2+/-3.8% in controls, p<0.001) with a preserved NMD (16.9+/-5.6% versus 15.2+/-4.8% in controls, p>0.05). Aortic strain and distensibility were lower and aortic stiffness index was higher in patients compared to controls (8.1+/-4.6 versus 5.8+/-2.9, p<0.01). Indexed LV diameters and mass were higher in patients. Systolic LV function was preserved, while 14.9% of patients had an impaired relaxation transmitral inflow pattern. Patients' LV mass index and diastolic mitral E wave deceleration time were positively correlated with aortic stiffness index (p<0.001).

CONCLUSION

Sickle-thalassemia is characterized by a complex vasculopathy, consisting of endothelial dysfunction and increased arterial stiffness, with a global effect on cardiovascular function.

Aortic Valve Replacement in a Patient With Thalassemia Intermedia

Pseudoxanthoma elasticum-like diffuse elastic tissue defects and hypercoagulability are two well-established features in beta-thalassemia, which play a key role in the development of a spectrum of collateral complications in these patients. We present here a middle-aged thalassemia intermedia patient with severe aortic stenosis caused by heavy calcification of the valve, a hallmark of pseudoxanthoma elasticum. The patient underwent a successful replacement of the valve, which is the first such operation ever reported in these patients. However, rapid thrombosis leaded to failure of the mechanical valve, despite proper antithrombotic therapy.

Oxidative stress in fibroblasts from patients with pseudoxanthoma elasticum: possible role in the pathogenesis of clinical manifestations

Pseudoxanthoma elasticum (PXE) is a genetic disease characterized by calcification and fragmentation of elastic fibres of the skin, cardiovascular system and eye, caused by mutations of the ABCC6 gene, which encodes the membrane transporter MRP6. The pathogenesis of the lesions is unknown. Based on studies of similar clinical and histopathological damage present in haemolytic disorders, our working hypothesis is that PXE lesions may result from chronic oxidative stress occurring in PXE cells as a consequence of MRP6 deficiency. Our results show that PXE fibroblasts suffer from mild chronic oxidative stress due to the imbalance between production and degradation of oxidant species. The findings also show that this imbalance results, at least in part, from the loss of mitochondrial membrane potential (DeltaPsi(m)) with overproduction of H2O2. Whether mitochondrial dysfunction is the main factor responsible for the oxidative stress in PXE cells remains to be elucidated. However, mild chronic generalized oxidative stress could explain the great majority of structural and biochemical alterations already reported in PXE.

Heart failure in beta-thalassemia syndromes: a decade of progress

The thalassemias are common monogenic disorders of hemoglobin synthesis. beta-thalassemias are the most important among the thalassemia syndromes and have become a worldwide clinical problem due to an increasing immigrant population. In beta-thalassemia major, regular blood transfusions are necessary early in life. Beta-thalassemia intermedia refers to a less severe phenotype, whereas beta-thalassemia/hemoglobin E disease encompasses a broad phenotypic spectrum. Blood transfusions and increased gastrointestinal iron absorption result in iron overload and tissue damage. Among patients with beta-thalassemia major, biventricular, dilated cardiomyopathy remains the leading cause of mortality. In some patients, a restrictive type of left ventricular cardiomyopathy or pulmonary hypertension is noted. The clinical course, although variable and occasionally fulminant, is more benign in recent than in older series. Myocarditis has been described as a cause of left-sided heart failure in younger patients. Pulmonary arterial hypertension is the principal cause of heart failure in beta-thalassemia intermedia. Chelation therapy has improved prognosis in beta-thalassemia major both by reducing the incidence of heart failure and by reversing cardiomyopathy. Estimation of the patient's cardiac risk is mainly based on clinical criteria and serial echocardiography. A new cardiovascular magnetic resonance technique will probably fulfill the need for more precise risk stratification in beta-thalassemia syndromes. By increasing the proportion of patients on optimal chelation, survival in beta-thalassemia major may further improve. Recent advances in gene therapy are expected to result in the long-awaited cure of this disease.

Pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a rare multisystem disorder characterised by progressive calcification and fragmentation of elastic fibres. Recent genetic advances have identified the underlying defect to the ABCC6 gene on chromosome 16p13.1. Patients typically develop cutaneous, ocular, and cardiovascular manifestations but there is considerable phenotypic variability. The skin changes are usually apparent in adulthood, and rarely observed in childhood. Since the prognosis of PXE largely depends on the extent of extracutaneous organ involvement early recognition, intervention and lifestyle adjustments are important to reduce morbidity. First-degree family members should be carefully examined for any cutaneous or ophthalmologic features of PXE.

Selected disorders of connective tissue: pseudoxanthoma elasticum, cutis laxa, and lipoid proteinosis

There has been progress made in the understanding of 3 Mendelian disorders: pseudoxanthoma elasticum, cutis laxa, and lipoid proteinosis cutis and mucosae. While they are primary connective tissue diseases, their names imply a connection to the skin, and in fact, it is often the dermatologist who makes the diagnosis. It seems rational that defects in various extracellular matrix proteins cause lipoid proteinosis or subtypes of cutis laxa, yet the discovery of a liver- and kidney-based transmembrane transporter as the culprit of pseudoxanthoma elasticum was rather surprising and may shed new light on elastic tissue homeostasis.

Cerebral small vessel disease in pseudoxanthoma elasticum: three cases

BACKGROUND

Cerebral small vessel disease is rarely described in association with pseudoxanthoma elasticum (PXE), a hereditary connective tissue disorder with skin, eye and vascular manifestations. This autosomally inherited elastic tissue disease has been attributed to mutations in the ABCC6 gene located on chromosome 16p13.1. Different stroke mechanisms are suggested in PXE patients, arterial hypertension and accelerated atherosclerosis being the leading ones.

CASE DESCRIPTIONS

Case 1: A 49-year-old man with history of mild hypertension presented with recurrent transient ischemic attacks. At the age of 42, evaluation for progressive visual loss and skin changes led to diagnosis of PXE. Brain magnetic resonance imaging (MRI) disclosed multiple lacunar infarctions and confluent periventricular white matter lesions (WML). Case 2: A 71-year-old woman with history of mild hypertension suffered right-sided stroke. Diagnosis of PXE was made at the age of 48 due to severe visual loss and skin changes. Brain MRI revealed multiple lacunar infarctions and subcortical ischemic leukoencephalopathy. Case 3: A 47-year-old woman with prominent skin changes and bilateral amblyopia developed right-sided weakness. Skin biopsy confirmed PXE. Several lacunar infarcts in deep white matter and pons were revealed on MRI.

DISCUSSION

We present three patients with clinical and histopathological features of PXE who presented with multiple lacunar strokes, two with extensive confluent WML. These cases illustrate that PXE is a rare but significant risk factor for small vessel disease and stroke in patients of all age groups. Occlusive small vessel disease and subsequent lacunar infarcts and WML represent important PXE manifestations.

Pseudoxanthoma elasticum: a clinical, pathophysiological and genetic update including 11 novel ABCC6 mutations

Pseudoxanthoma elasticum (PXE) is an inherited systemic disease of connective tissue primarily affecting the skin, retina, and cardiovascular system. It is characterised pathologically by elastic fibre mineralisation and fragmentation (so called "elastorrhexia"), and clinically by high heterogeneity in age of onset and the extent and severity of organ system involvement. PXE was recently associated with mutations in the ABCC6 (ATP binding cassette subtype C number 6) gene. At least one ABCC6 mutation is found in about 80% of patients. These mutations are identifiable in most of the 31 ABCC6 exons and consist of missense, nonsense, frameshift mutations, or large deletions. No correlation between the nature or location of the mutations and phenotype severity has yet been established. Recent findings support exclusive recessive inheritance. The proposed prevalence of PXE is 1/25,000, but this is probably an underestimate. ABCC6 encodes the protein ABCC6 (also known as MRP6), a member of the large ATP dependent transmembrane transporter family that is expressed predominantly in the liver and kidneys, and only to a lesser extent in tissues affected by PXE. The physiological substrates of ABCC6 remain to be determined, but the current hypothesis is that PXE should be considered to be a metabolic disease with undetermined circulating molecules interacting with the synthesis, turnover, or maintenance of elastic fibres.

Identification of a DNA methylation-dependent activator sequence in the pseudoxanthoma elasticum gene, ABCC6

ABCC6 encodes MRP6, a member of the ABC protein family with an unknown physiological role. The human ABCC6 and its two pseudogenes share 99% identical DNA sequence. Loss-of-function mutations of ABCC6 are associated with the development of pseudoxanthoma elasticum (PXE), a recessive hereditary disorder affecting the elastic tissues. Various disease-causing mutations were found in the coding region; however, the mutation detection rate in the ABCC6 coding region of bona fide PXE patients is only approximately 80%. This suggests that polymorphisms or mutations in the regulatory regions may contribute to the development of the disease. Here, we report the first characterization of the ABCC6 gene promoter. Phylogenetic in silico analysis of the 5' regulatory regions revealed the presence of two evolutionarily conserved sequence elements embedded in CpG islands. The study of DNA methylation of ABCC6 and the pseudogenes identified a correlation between the methylation of the CpG island in the proximal promoter and the ABCC6 expression level in cell lines. Both activator and repressor sequences were uncovered in the proximal promoter by reporter gene assays. The most potent activator sequence was one of the conserved elements protected by DNA methylation on the endogenous gene in non-expressing cells. Finally, in vitro methylation of this sequence inhibits the transcriptional activity of the luciferase promoter constructs. Altogether these results identify a DNA methylation-dependent activator sequence in the ABCC6 promoter.

Antioxidant deficit and enhanced susceptibility to oxidative damage in individuals with different forms ofα-thalassaemia

alpha-Thalassaemia is a common red cell disorder in Taiwan, affecting 6-8% of Taiwanese. Previous studies have shown that reactive oxygen species are generated in increased amounts in thalassaemic red cells. This implies the possible alteration of redox status in thalassaemic patients, which may adversely affect their health. In the present study, the redox status of patients with alpha-thalassaemia trait and haemoglobin H (Hb H) disease was investigated. Lipid peroxidation, as measured by the level of plasma thiobarbituric acid reactive substances (TBARS), was increased in alpha-thalassaemic patients, with the highest level of TBARS in Hb H disease patient. The plasma levels of vitamin A, C, and E were significantly lower in alpha-thalassaemic patients than in controls. The overall antioxidant capacity in plasma was inversely correlated with the severity of alpha-globin gene defect: the more severe the form of alpha-thalassaemia, the lower the overall antioxidant capacity in plasma. Erythrocytes isolated from alpha-thalassaemia patients had lower levels of vitamin E, glutathione, catalase and superoxide dismutase. In addition, these alpha-thalassaemic red cells were more susceptible to hydrogen peroxide-induced lipid peroxidation and decrease in deformability. All these data suggest that the alpha-thalassaemic patients suffer from increased oxidative stress and antioxidant deficit, which may complicate the pathophysiology of alpha-thalassaemia.

Fluctuations of intracellular iron modulate elastin production

Production of insoluble elastin, the major component of elastic fibers, can be modulated by numerous intrinsic and exogenous factors. Because patients with hemolytic disorders characterized with fluctuations in iron concentration demonstrate defective elastic fibers, we speculated that iron might also modulate elastogenesis. In the present report we demonstrate that treatment of cultured human skin fibroblasts with low concentration of iron 2-20 microm (ferric ammonium citrate) induced a significant increase in the synthesis of tropoelastin and deposition of insoluble elastin. Northern blot and real-time reverse transcription-PCR analysis revealed that treatment with 20 microm iron led to an increase of approximately 3-fold in elastin mRNA levels. Because treatment with an intracellular iron chelator, desferrioxamine, caused a significant decrease in elastin mRNA level and consequent inhibition of elastin deposition, we conclude that iron facilitates elastin gene expression. Our experimental evidence also demonstrates the existence of an opposite effect, in which higher, but not cytotoxic concentrations of iron (100-400 microm) induced the production of intracellular reactive oxygen species that coincided with a significant decrease in elastin message stability and the disappearance of iron-dependent stimulatory effect on elastogenesis. This stimulatory elastogenic effect was reversed, however, in cultures simultaneously treated with high iron concentration (200 microm) and the intracellular hydroxyl radical scavenger, dimethylthiourea. Thus, presented data, for the first time, demonstrate the existence of two opposite iron-dependent mechanisms that may affect the steady state of elastin message. We speculate that extreme fluctuations in intracellular iron levels result in impaired elastic fiber production as observed in hemolytic diseases.

Cardiac status in well-treated patients with thalassemia major

OBJECTIVE

To assess cardiac status in a large group of patients with thalassemia major who had been treated in a standard way since their early infancy with intensive transfusions and deferoxamine chelation therapy and who had good compliance with this regimen.

METHODS AND RESULTS

We assessed clinically and echocardiographically 202 thalassemia major patients aged 27.3 +/- 6.3 yr and 75 age and sex-matched healthy controls. Overt cardiac disease was encountered in 14 patients (6.9%), including 5 (2.5%) with congestive heart failure, aged 26-37 yr, and 9 with systolic left ventricular (LV) dysfunction, aged 23-37 yr. Ten patients (5.0%) had a history of pericarditis. Left atrial and LV diameters, LV mass and cardiac output were significantly higher in patients than in controls, while peripheral resistance and LV afterload were significantly lower. Relative LV wall thickness did not differ between patients and controls, but it was significantly lower in patients with overt cardiac disease compared to those without (P < 0.05). Restrictive LV filling was observed in 37.6% of patients and was significantly more frequent in cases with overt cardiac disease (P < 0.01). Pulmonary hypertension was practically absent. Hematological parameters and pulmonary artery pressure levels were not independently associated with the presence of overt cardiac disease.

CONCLUSION

Strict lifelong adherence to the standard transfusion and deferoxamine therapy reduces considerably the occurrence of heart failure, LV dysfunction and pericarditis, prevents early heart failure and pulmonary hypertension, but does not eliminate completely cardiac disease in patients with thalassemia major.

Tumefactive lipedema with pseudoxanthoma elasticum-like microscopic changes

BACKGROUND

Lipedema is a condition characterized by diffuse, bilaterally symmetrical, painful swelling of the legs and buttocks. Microscopically, there are dermal and septal edema, adipocyte degeneration, and numerous mast cells, features held in common with lipedematous alopecia.

CASE REPORT

We present the case of a 60-year-old woman with a long history of bilateral leg masses with microscopic features of lipedema. In addition, elastic-fiber changes typical of pseudoxanthoma elasticum (PXE) were discovered within the subcutaneous septa in three separate specimens obtained from an affected extremity. The patient did not have other clinical findings of PXE, although there was a history of both hypertension and congestive heart failure.

CONCLUSION

This tumefactive presentation of lipedema has not been previously described. Regarding the elastic-tissue abnormalities, the patient could have either a subclinical form of PXE, perhaps predisposing to lipedema, or secondary elastic-tissue changes resulting from the massive edema. If the latter is the case, then this could represent an unusual manifestation of localized acquired cutaneous PXE (calcific elastosis).

Hypercoagulability in sickle cell disease: a curious paradox

There is evidence of activation of both blood coagulation and platelets in sickle cell disease. For example, plasma samples obtained in the steady state and during painful crisis demonstrate high levels of thrombin generation, depletion of anticoagulant proteins, and abnormal activation of the fibrinolytic system. Similarly, exposure of surface markers such as CD62P and CD40L, along with increased circulating levels of thrombospondin, signal platelet activation. In addition to its effects on the cleavage of fibrinogen and its ability to activate platelets, the increase in circulating thrombin levels, with its wide-ranging effects on endothelial cells and blood vessels, may be important in the pathophysiology of sickle cell disease. Therefore, treatments that could decrease thrombin generation or platelet activation may be beneficial in both the treatment of sickle cell disease and the prevention of complications that characterize this genetic disorder. This review discusses hypercoagulability in the various forms of sickle cell disease, including homozygous sickle cell anemia, hemoglobin SC disease, hemoglobin SD disease, and sickle cell-beta-thalassemia.

Acquired Pseudoxanthoma elasticum-like syndrome in beta-thalassaemia patients

A significant number of patients diagnosed with beta-thalassaemia develop clinical and histopathological manifestations similar to those of an inherited disorder called Pseudoxanthoma elasticum (PXE). The inherited PXE is caused by mutations in the ATP-binding cassette, subfamily C (CFTR/MRP), member 6 (ABCC6) gene and is characterized by mineralized elastic fibres in dermal, vascular and ocular tissues. As no disease-causing variant was found in the ABCC6 gene of 10 beta-thalassaemia patients with a PXE-like phenotype, the present study suggests that the PXE-like symptoms in these beta-thalassaemic patients are not related to ABCC6 mutations.

Pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a heritable disease characterized by dermal, ocular, and vascular lesions that result from degeneration of the elastic fibers. Recently, the ATP-binding cassette subfamily C member 6 (ABCC6) gene has been demonstrated to be responsible for PXE, and 43 mutations have been identified to date. However, it is still unknown now mutations in the ABCCC6 gene can lead to manifestations of PXE.