[Prevention of genetic diseases : the return of the family practitioner ?] / Prévention des maladies génétiques. Le retour du médecin de famille ?

BACKGROUND: Information to kin is one of the major ethical problems of the new genetics. In France, the revised bioethics law in 2011 created the possibility for patients to authorize professionals, under certain conditions, to directly contact their relatives at risk. Beyond this, other actors, such as GPs, could however play a role in this process. METHODS: Our article is based on an ethnographic-type sociological study by observations and semi-structured interviews with patients (n=59) and genetic professionals (n=16) that took place from 2014 to 2016 in three genetic hospital wards in France and Canada. It focuses particularly on genetic predispositions to breast and ovarian cancers as well as genetic hemochromatosis. RESULTS: Because of its position as a primary care specialist, the general practitioner can play a decisive role in the process of informing relatives about genetic disorders. Upstream of the genetic test, the generalist, thanks to his knowledge of the family context of his patients, can play a referral role towards a specialized consultation. Downstream, it can also ensure a more effective follow-up of the information procedures undertaken by its patients thanks to the medical follow-up that it carries out. CONCLUSION: The data collected during our study highlight the unprecedented place that could be that of the general practitioner in the field of prevention in genetics. At the articulation between primary care and highly specialized care, it is the figure of the "family" doctor who seems to be called here to be renewed by genetics.

Factors predictive of leg-ulcer healing in sickle cell disease: a multicentre, prospective cohort study.

BACKGROUND: Leg ulcers (LUs) are a chronic and severe complication of sickle cell disease (SCD). A prospective study in patients with SCD to identify factors associated with complete healing and recurrence of LUs is lacking. OBJECTIVES: To determine clinical and biological factors associated with SCD-LU complete healing and recurrence. METHODS: This prospective, observational cohort study was conducted at two adult SCD referral-centre sites (2009-2015) and included 98 consecutive patients with at least one LU lasting ≥ 2 weeks. The primary end points compared patients with healed vs. nonhealed LUs at week 24, and patients with vs. without recurrence during follow-up. RESULTS: The median (interquartile range) LU area, duration and follow-up were, respectively, 6·2 cm2 (3-12·8), 9 weeks (4-26) and 65·8 weeks (23·8-122·1). At week 24, LUs were healed in 47% of patients, while 49% of LUs recurred. Univariate analyses identified inclusion LU area < 8 cm2 (82% vs. 35%; P < 0·001), inclusion LU duration < 9 weeks (65% vs. 35%; P = 0·0013) and high median fetal haemoglobin level (P = 0·008) as being significantly associated with complete healing at week 24, and low lactate dehydrogenase level (P = 0·038) as being associated with recurrence. Multivariate analyses retained LU area < 8 cm2 (odds ratio 6·73, 95% confidence interval 2·35-19. 31; P < 0·001) and < 9 weeks' duration (OR 3·19, 95% confidence interval 1·16-8·76; P = 0·024) as being independently associated with healing at week 24. Factors independently associated with recurrence could not be identified. CONCLUSIONS: SCD-LU complete healing is independently associated with the clinical characteristics of LUs rather than the clinical or biological characteristics of SCD.

The use of rituximab to prevent severe delayed haemolytic transfusion reaction in immunized patients with sickle cell disease.

BACKGROUND: Delayed haemolytic transfusion reaction (DHTR) is mainly caused by an immune response to transfused red blood cells (RBCs). Immunized patients have a high risk of producing antibodies in response to further transfusion. Controlling the immune response to RBCs is therefore a major goal in sickle cell disease (SCD). STUDY DESIGN: We report an observational study of eight alloimmunized SCD patients with history of severe DHTR who were treated with rituximab before a new transfusion to prevent further immunization and DHTR. RESULTS: Five patients showed a good clinical outcome following transfusion preceded by preemptive treatment with rituximab. The remaining patients presented mild DHTR. In all patients, the results of post-transfusion screening tests were identical to those of pretransfusion tests; no newly formed antibodies were detected. CONCLUSION: These cases suggest that rituximab prevents at least occurrence of newly formed antibodies in high responders and minimizes the risk of severe DHTR. This study confirms that DHTR is complex in SCD and does not rely only on the classical antigens/antibodies conflict. Considering potentially serious adverse effect of rituximab, this treatment should be considered cautiously, and only when transfusion is absolutely necessary in patients with history of severe DHTR linked to immunization.

Le globule rouge drépanocytaire. Données génétiques et structurelles: The sickle cell. Genetic and structural data.

Sickle cell disease is syndromic, associating a hemolytic anemia, a vaso-obstructive vascular disease, and an infectious risk linked to the precocity of the splenic function loss. The willingly hyperacute and potentially fatal character of the two last elements of the pathophysiologic syndrome, has, quite rightly, focused the therapeutic researches on them. Great success in those two domains have allowed a very important gain in life expectancy. However, chronic progressive organ dysfunction began to appear in older than 25 years-old patients. It concerns mainly renal, hepatic, cardiac functions and pulmonary arterial pressure and may lead to organ failure and premature death. Since some 25 years, the clinical research demonstrated an association between such complications and intravascular hemolytic rate, and it turned to a causative relationship. This present paper try to summarize the actual knowledge on the structural and genetic aspects of sickle cell anemia hemolysis. © 2023 Société nationale française de médecine interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.

Evaluation of a prophylactic transfusion program on obstetric outcomes in pregnant women with sickle cell disease: A single centre retrospective cohort study.

OBJECTIVE: To evaluate the effects of a prophylactic transfusion program (TP) on obstetric and perinatal outcomes in pregnant women with sickle cell disease (SCD). METHODS: This retrospective cohort study included all singleton pregnancies among women with SCD in a French university tertiary care center between 1 January 2004 and 31 December 2017. The TP group included patients selected according to the French guidelines who received regular red blood cell transfusions during pregnancy until delivery. The factors associated with TP indication [year of birth, SCD genotype, history of acute chest syndrome and delayed hemolysis transfusion reaction (DHTR) risk score] were taken into account in a propensity score. A composite obstetric adverse outcome was defined associating birth before 34 gestational weeks and/or pre-eclampsia and/or small for gestational age and/or abruption and/or stillbirth and/or maternal death and/or neonatal death. RESULTS: In total, 246 pregnancies in 173 patients were analyzed. Twenty-two pregnancies with a history of DHTR were excluded. A higher frequency of TP was found before 2013 [119/148 (80.4%) vs 38/76 (50%); p < 0.001]. Rates of preterm birth before 34 gestational weeks (5.6% vs 19.7%; p = 0.001), vaso-occlusive crisis (36.5% vs. 61.8%; p < 0.001), and acute chest syndrome (6.1% vs. 14.5%; p = 0.04) during pregnancy were decreased significantly in the TP group. Among the groups with and without composite obstetric adverse outcomes, the frequency of TP was 52.6% and 74.7%, respectively [odds ratio (OR) 0.30, 95% confidence interval (CI) 0.09-1.02]. The multivariate analysis shows that the TP was associated with a significant reduction in the risk of composite obstetric adverse outcomes (OR 0.28, 95% CI 0.08-0.97; p = 0.04). CONCLUSION: A red blood cell TP may have an independent protective effect on maternal and perinatal adverse outcomes during pregnancy in women with SCD.

Retinal photocoagulation for proliferative sickle cell retinopathy: a prospective clinical trial with new sea fan classification.

PURPOSE: To compare the clinical outcome of stage III proliferative sickle cell retinopathy (PSR) treated by peripheral retinal scatter photocoagulation to natural course disease. METHODS: Long-term follow-up of 101 patients enrolled in a prospective trial of photocoagulation for PSR has been completed. Among 202 eyes of 101 patients enrolled at the University Eye Clinic of Créteil, 73 eyes showed a stage III PSR, which the authors further divided into five new grades (A, B, C, D, E) considering size, hemorrhage, fibrosis, and visible vessels. Grading was based on a three-mirror fundus examination, 360 degrees color photographs, and fluorescein angiography. Mean follow- up was 4 years. RESULTS: Thirty-eight treated eyes and 35 untreated eyes were included in this study. The evolution was not statistically significant between treated and untreated groups concerning flat sea fan <1 MPS disc area (grade A) or elevated sea fan with partial fibrosis (grade C). Progression and regression were compared between the two groups for grade B, resulting statistically significant (p<0.05). Nine complications (13%) were observed, which only occurred in untreated patients with elevated sea fan and hemorrhage (grade B) or complete fibrosed sea fan with well defined vessels (grade E) (p<0.05). CONCLUSIONS: These data suggest that patients with grade A or C new sea fan classification should not be initially treated but observed.

[Study of 206 transfused sickle cell disease patients: immunization, transfusion safety and red blood cell supply]. / Etude d'une cohorte de 206 patients drépanocytaires adultes transfusés: immunisation, risque transfusionnel et ressources en concentrés globulaires.

BACKGROUND: Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion. METHODS AND RESULTS: Immunohematological data of 206 chronically transfused patients have been collected as well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally, this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens. CONCLUSION: To insure optimal transfusion safety for sickle cell disease patients, three points have to be improved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system.

Role of Lu/BCAM in abnormal adhesion of sickle red blood cells to vascular endothelium.

Lutheran (Lu) blood group and Basal Cell Adhesion Molecule (BCAM) antigens are both carried by two glycoprotein (gp) isoforms of the immunoglobulin superfamily representing receptors for laminin alpha5 chain. They are expressed in red blood cells, in endothelial cells of vascular capillaries and in epithelial cells of several tissues. Lu/BCAM gps are overexpressed in sickle red blood cells (SS RBCs). Stimulation of SS RBCs by epinephrine activates the PKA depending signaling pathway and induces reinforced Lu/BCAM-mediated adhesion to laminin10/11. We have analyzed the phosphorylation state of Lu/BCAM long isoform cytoplasmic tail and showed that it is phosphorylated by CKII, GSK3b and PKA. Phosphorylation of this isoform in transfected K562 cells is stimulated by effectors of the PKA pathway and induces cell adhesion to laminin10/11. Lu/BCAM gps are highly expressed in endothelial cells and exhibit potential integrin binding motifs. We showed that they interact with integrin alpha4beta1, the unique integrin expressed on the surface of young reticulocytes. Adhesion assays under flow conditions showed that SS RBCs adhere to primary human endothelial cells (HUVEC) after selective activation of intergin alpha4beta1 and that this adhesion is mediated by endothelial Lu/BCAM gps. Our studies show that Lu/BCAM gps expressed either on erythroid or on endothelial cells are involved in SS RBC-endothelium interactions and could play a role in the abnormal adhesion of SS RBCs to vascular endothelium contributing to the vaso-occlusive crises reported for sickle cell disease patients.

Abnormality of phospholipid transverse diffusion in sickle erythrocytes.

We have used spin-labeled analogues of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine to compare the transverse diffusion rates of lipids in normal and sickle erythrocytes. The beta-chain of the spin-labeled lipids was a short chain (five carbons) providing the spin labels with a relative water solubility, and hence permitting their rapid incorporation into cell membranes. The orientation of the labeled lipids in the membranes was assayed by selective chemical reduction of the nitroxide labels embedded in the outer leaflet. We have found that all three spin-labeled phospholipids are initially incorporated in the outer leaflet. Upon incubation at 4 degrees C the aminophospholipids, not the phosphatidylcholine, diffuse toward the inner leaflet within 3 h. The transverse diffusion rate of aminophospholipids is reduced by 41% (phosphatidylserine) and 14% (phosphatidylethanolamine) in homozygote sickle cells (SS) when compared with normal cells (AA) or heterozygote cells (AS or SC). At equilibrium the asymmetric distribution of spin-labeled phospholipids resulting from this selective diffusion is also reduced in SS cells when compared with AA, SC, or AS cells. This reduced asymmetry was not found in a reticulocyte-rich blood sample (hemoglobin A), indicating that the age of the cell cannot be responsible for this phenomenon. Moreover, because at low temperatures the sickling process does not occur, the observed perturbations in phospholipid organization reflect preexisting membrane abnormalities in sickle cells. Ghosts loaded with ATP give the same results. Varying the concentration of intracellular calcium had no effect on lipid diffusion, except at very high free calcium concentrations (3 microM) when diffusion was practically abolished. We suggest that membrane protein alterations may be part of the explanation of the observed abnormalities.

Oral magnesium supplements reduce erythrocyte dehydration in patients with sickle cell disease.

Intracellular polymerization and sickling depend markedly on the cellular concentration of sickle hemoglobin (Hb S). A possible therapeutic strategy for sickle cell disease is based on reducing the cellular concentration of Hb S through prevention of erythrocyte dehydration. The K-Cl cotransporter is a major determinant of sickle cell dehydration and is inhibited by increasing erythrocyte Mg content. We studied 10 patients with sickle cell disease before treatment and after 2 and 4 wk of treatment with oral Mg supplements (0.6 meq/kg/d Mg pidolate). Hematological parameters, erythrocyte Na, K, and Mg content, erythrocyte density, membrane transport of Na and K, and osmotic gradient ektacytometry were measured. We found significant increases in sickle erythrocyte Mg and K content and reduction in the number of dense sickle erythrocytes. Erythrocyte K-Cl cotransport was reduced significantly. We also observed a significant reduction in the absolute reticulocyte count and in the number of immature reticulocytes. Ektacytometric analysis showed changes indicative of improved hydration of the erythrocytes. There were no laboratory or clinical signs of hypermagnesemia. Mild, transient diarrhea was the only reported side effect. We conclude that oral Mg supplementation reduces the number of dense erythrocytes and improves the erythrocyte membrane transport abnormalities of patients with sickle cell disease.

Rituximab for prevention of delayed hemolytic transfusion reaction in sickle cell disease.

Delayed hemolytic transfusion reaction (DHTR), a life-threatening transfusion complication in sickle cell disease (SCD), is characterized by a marked hemoglobin drop with destruction of both transfused and autologous red blood cells (RBCs) and exacerbation of SCD symptoms. One mechanism of RBCs destruction is auto-antibody production secondary to transfusion. As rituximab specifically targets circulating B cells, we thought that it could be beneficial in preventing this immune-mediated transfusion complication. We report the case of a SCD patient who previously experienced DHTR with auto-antibodies and who needed a new transfusion. DHTR recurrence was successfully prevented by rituximab administration prior transfusion, supporting the safe use of rituximab to prevent DHTR in SCD patients as a second line approach when other measures failed.

The natural history of asymptomatic osteonecrosis of the femoral head in adults with sickle cell disease.

BACKGROUND: Osteonecrosis of the femoral head is a frequent complication in adult patients with sickle cell disease. However, little is known about the natural history of asymptomatic lesions. METHODS: One hundred and twenty-one patients (121 hips) with sickle cell disease and asymptomatic osteonecrosis of the femoral head that was contralateral to a hip with symptomatic osteonecrosis were identified with magnetic resonance imaging between 1985 and 1995. The lesions were graded with use of the Steinberg classification system. The patients were followed with annual plain radiographs. The mean duration of follow-up was fourteen years. RESULTS: At the time of the initial evaluation, fifty-six hips were classified as Steinberg stage 0, forty-two hips were classified as Steinberg stage I, and twenty-three hips were classified as Steinberg stage II. At the time of the most recent follow-up, pain had developed in 110 previously asymptomatic hips (91%) and collapse had occurred in ninety-three hips (77%). Symptoms always preceded collapse. Of the fifty-six hips that were classified as Steinberg stage 0 at the time of the initial evaluation, forty-seven (84%) had symptomatic osteonecrosis and thirty-four (61%) had collapse at the time of the most recent follow-up. Of the forty-two asymptomatic stage-I hips, forty (95%) became symptomatic within three years and thirty-six (86%) had collapse of the femoral head. Of the twenty-three asymptomatic stage-II hips, all became symptomatic within two years and all collapsed; the mean interval between the onset of pain and collapse was eleven months. At the time of the final follow-up, ninety-one hips (75%) had intractable pain and required surgery. CONCLUSIONS: Untreated asymptomatic osteonecrosis of the femoral head in patients with sickle cell disease has a high likelihood of progression to pain and collapse. Because of the high prevalence of complications after total hip arthroplasty in patients with this disease, consideration should be given to early surgical intervention with other procedures in an attempt to retard progression of the disease.

[Sickle cell disease in France in 2006: results and challenges]. / La drépanocytose en France en 2006: acquis et défis.

Sickle cell disease is currently recognized as the most frequent genetic disease screened in the neonatal period in France, and begins to be funded by Public Health Authorities. Despite these issues, SCD is still largely unknown, in particular by general public and practitioners, and education about the disease has to be intensified. Respective roles of proximate and reference centres have to be better defined. Screening of heterozygous patients remains to be organized. Limits of definition of a severe form, and therapeutic options need to be debated.

[Symptomatic extramedullary haematopoiesis in ß-thalassemia: A retrospective single centre study]. / Hématopoïèse extra-médullaire symptomatique au cours des ß-thalassémies: étude rétrospective monocentrique.

INTRODUCTION: Symptomatic extramedullary hematopoiesis (EH) is a rare but potentially severe phenomenon which occurs in ß-thalassemia. There are no treatment guidelines. METHODS: Retrospective single centre study including the cases of symptomatic EH encountered between 1997 and 2014 in a unit specialised in red blood cell genetic disorders. Description of clinical, biological and radiological characteristics of the patients, treatments received, and outcomes. RESULTS: Among 182 ß-thalassemia patients followed during the study period, 7 cases of symptomatic EH were diagnosed. They were 5 men and 2 women, and their mean age was 37 years. Four patients were splenectomised, two patients were regularly transfused, and four patients had already received erythropoietin. EH was localised in intravertebral areas and responsible for dorsal spinal cord compression in 5 patients, in paravertebral dorsal area in 1 patient, and in presacral area in 1 patient. The mean hemoglobin level at diagnosis was 7.9 g/dL. Treatment administered included: red cell transfusion in 6 cases, associated with hydroxyurea in 5 cases and/or radiotherapy in 3 patients. One patient was treated with surgery and HU. After a median follow-up of 41 months, clinical recovery was complete in 2 patients and partial in 5 patients. CONCLUSION: EH must be suspected in ß-thalassemia in patients presenting clinical signs of organ compression, and a typical radiological aspect. The functional prognosis depends on the rapidity of treatment, which includes red blood cell transfusion, hydroxyurea, radiotherapy, and rarely surgery. Long-term outcome is uncertain.

The calmodulin-stimulated (Ca2+ + Mg2+)-ATPase in hemoglobin S erythrocyte membranes: effects of sickling and oxidative agents.

A decrease in the reactivity of erythrocyte membrane (Ca2+ + Mg2+)-ATPase to calmodulin stimulation has been observed in aging red cells and in various types of hemolytic anemias, particularly in sickle red cell membranes. Unlike the aging process, the defect in the (Ca2+ + Mg2+)-ATPase from SS red blood cells is not secondary to a decrease in calmodulin activity and is already present in the least dense SS red blood cells separated on a discontinuous density gradient. Deoxygenated AS red cells were forced to sickle by lowering the pH, raising the osmolarity of the buffer (sickling pulse). Under these conditions an inhibition of the calmodulin-stimulated enzyme was observed only if several cycles of oxygenation/deoxygenation were applied. No alteration of the enzyme could be detected after submitting AS red blood cells to other conditions or in AA red blood cells submitted to the same treatments. This suggests that oxidative processes are involved in the alterations of the (Ca2+ + Mg2+)-ATPase activity. Treatment of membranes from AA erythrocytes by thiol group reagents and malondialdehyde, a by-product of auto-oxidation of membrane unsaturated lipids and a cross-linking agent of cytoskeletal proteins, led to a partial inhibition of the calmodulin-stimulated (Ca2+ + Mg2+)-ATPase. We postulate that the hyperproduction of free radicals described in the SS red blood cells and involved in the destabilization of the membrane may be also responsible for the (Ca2+ + Mg2+)-ATPase failure.

Functional and NMR studies of Hb Sassari (Asp-126 alpha----His); role of the inter-subunit contacts in the affinity control of human hemoglobin.

The oxygen affinity of hemoglobin Sassari (Asp-126 alpha----His), a variant substituted in the alpha 1 beta 1 interface, was found to be 8-times greater relative to normal adult human hemoglobin. Study of the exchangeable hydrogen-bonded protons by NMR spectroscopy shows only minor changes at the alpha 1 beta 1 interface. In particular, the resonance previously assigned to the proton of the hydrogen bond Asp-126 alpha 1. . . Tyr-35 beta 1 in normal hemoglobin is still present in the variant spectrum, suggesting that His-126 alpha can also form a hydrogen bond with the Tyr-35 beta. The possible explanation of the increased affinity of hemoglobin Sassari and other variants substituted in the same structural region is discussed in terms of perturbations of the equilibrium between the two quaternary states.

Hb Villaverde [beta 89 (F5) Ser-->Thr]: the structural modification of an intrasubunit contact is responsible for a high oxygen affinity.

Hb Villaverde [beta 89 (F5) Ser-->Thr], identified in a Spanish patient, is a new human hemoglobin variant, electrophoreticaly silent, responsible for a severe erythrocytosis. This abnormal hemoglobin displays a very high oxygen affinity and a markedly reduced cooperativity that is partly restored in the presence of IHP. Determination of the structural abnormality was achieved on a mixture of the normal and abnormal beta-chains. After isolation of the abnormal tryptic peptide by RP-HPLC, its sequence was determined by mass spectrometry. The structural abnormality disturbs the intrasubunit interaction between helices F and H and, thus, may weaken the C-terminal bonds of the deoxy conformation and the heme contacts of several hydrophobic residues. Hb Villaverde demonstrates that this intrasubunit contact between helices F and H is essential for the cohesion of the hemoglobin molecule.

Hemoglobin Rouen (alpha-140 (HC2) Tyr-->His): alteration of the alpha-chain C-terminal region and moderate increase in oxygen affinity.

Hb Rouen (alpha 140(HC2) Tyr-->His) is a moderately high oxygen-affinity variant that was found in coincidence with polycythemia vera in a French patient. This hemoglobin provides an example of an alteration of the C-terminus of the alpha-chain, a region involved in the mechanisms of allosteric regulation. The increase in oxygen-affinity and decrease in cooperativity of this variant is much smaller than that resulting from the same substitution in the beta-chain. This model provides additional evidence for the inequivalence between the alpha- and beta-subunits.