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1.
Med Trop (Mars) ; 70(5-6): 449-53, 2010 Dec.
Article in French | MEDLINE | ID: mdl-21520645

ABSTRACT

Sickle cell disease is a genetic blood disorder caused by a glutamic to valine acid substitution in the beta chain of the hemoglobin protein. It was first reported in the United States where most research has been carried out on subjects of African descent. It is diffused throughout the world. Epidemiological data show that the highest incidence of sickle cell anemia is in sub-Saharan Africa where the severest forms are often fatal in children under the age of 5 years. The clinical course of the disease in Africa is comparable to that described in industrialized countries. The three cardinal symptoms are hemolytic anemia, painful episodes, and susceptibility to infection. Genotype and phenotype variations have been observed from one zone to another in Africa. Greater severity is due to a combination of various factors including constant coexistence with Plasmodium falciparum malaria and omnipresence of pyogenic factors as well as to the unfavorable demographic setting involving endogamy, poor healthcare facilities, and poor socio-economic conditions. A hundred years of research has provided a good understanding of the pathophysiological mechanisms that can sometimes be improved by to primary hydroxyurea therapy. Sickle cell disease remains a major health problem in Africa where patients do not currently benefit from the same treatment as in industrial countries.


Subject(s)
Anemia, Sickle Cell/epidemiology , Africa/epidemiology , Anemia, Sickle Cell/diagnosis , Anemia, Sickle Cell/genetics , Bacterial Infections/epidemiology , Humans , Malaria, Falciparum/epidemiology , Opportunistic Infections/epidemiology
2.
Med Trop (Mars) ; 70(5-6): 454-8, 2010 Dec.
Article in French | MEDLINE | ID: mdl-21520646

ABSTRACT

It has been 100 years since Herrick published the first medical case report of sickle cell disease. In 1949, Pauling discovered hemoglobin S (HbS). As early as the 1960-70s, emerged a coherent detailed molecular-level description of pathophysiology of sickle disease. It involved polymerization of deoxyhemoglobin S with formation of long fibers inside red blood cells (RBC) causing a distorted sickle shape and shortened lifespan. These changes constitute the basic disease process and account for hemolytic anemia and for obstructive events underlying vasoocclusive crises (VOC). However, they do not explain the mechanisms that trigger VOC. The purpose of this review is to present recent data on dehydration of sickle cell RBC, abnormalities in RBC adhesion to the vascular endothelium, the role of inflammatory events and of activation of all cells in the vessel, and abnormalities of vascular tone and carbon monoxide metabolism. These data provide new insight into the pathophysiology of the first molecular disease.


Subject(s)
Anemia, Sickle Cell/physiopathology , Cell Adhesion , Endothelium, Vascular/cytology , Erythrocyte Membrane/metabolism , Erythrocytes/cytology , Hemoglobin, Sickle/metabolism , Humans , Vascular Diseases/etiology
3.
Eur J Med Genet ; 52(5): 328-32, 2009.
Article in English | MEDLINE | ID: mdl-19454329

ABSTRACT

BACKGROUND: The 22q13.3 deletion syndrome (or Phelan-McDermid syndrome, MIM 606232) is characterized by developmental delay, absent or severely delayed speech, neonatal hypotonia, autistic behavior, normal to accelerated growth, and minor dysmorphic facial features. Among the three genes in the minimal critical region (from the centromere to the telomere: SHANK3, ACR and RABL2B), the defect in the SHANK3 gene is considered to be the cause of the neurobehavioral symptoms. OBJECTIVE: We describe the molecular characterization of a de novo interstitial del(22)(q13.3q13.3) disrupting the SHANK3 gene in a child with a phenotype compatible with the 22q13.3 deletion syndrome. METHODS: Clinical work-up included clinical histories, physical, neurological, and ophthalmological examinations, and imaging of the brain. Commercially available MLPA for subtelomeric analysis, FISH specific probes and quantitative real-time PCR were used to characterize the rearrangement. RESULTS: Subtelomere analysis by MLPA showed a discrepancy between P036B and P070 kits (MCR Holland): the P070 MLPA 22q probe (targeting the ARSA gene) showed a deletion but the P036B one (targeting the RABL2B gene) showed a normal result. FISH analysis using LSI TUPLE1/LSI ARSA (Vysis) probes confirmed deletion of ARSA, whereas FISH with N25/N85A3 (Cytocell) probes, targeting the SHANK3 locus was normal. Supplemented FISH analysis using BAC clones allowed us to specify the centromeric breakpoint region of the interstitial deletion between clones RP11-354I12 and RP11-232E17, at less than 2 Mb from the telomere. Quantitative real-time PCR of exon 5, 22 and 24 and intron 9 of SHANK3 showed that the telomeric breakpoint occurred between intron 9 and exon 22. CONCLUSIONS: These data highlight the difficulty of performing an appropriate test aimed at looking for cryptic 22q13.3 deletion. Furthermore, the molecular characterization of this interstitial 22q13.3 deletion contributes to the clinical and genetic delineation of the 22q13.3 deletion syndrome.


Subject(s)
Carrier Proteins/genetics , Chromosome Deletion , Chromosomes, Human, Pair 22 , Child , Chromosome Banding , DNA/genetics , DNA/isolation & purification , Female , Fluorescein-5-isothiocyanate/metabolism , Fluorescent Dyes/metabolism , France , Humans , In Situ Hybridization, Fluorescence , Indoles/metabolism , Nerve Tissue Proteins , Nucleic Acid Amplification Techniques , Polymerase Chain Reaction , Syndrome , Xanthenes/metabolism
5.
J Clin Pathol ; 62(1): 31-3, 2009 Jan.
Article in English | MEDLINE | ID: mdl-19103855

ABSTRACT

BACKGROUND: As a result of population growth in African-Caribbean regions of overseas France, and now immigration essentially from North and sub-Saharan Africa to mainland France, neonatal screening for sickle cell disease (SCD) has been performed in France since 1985 in Guadalupe and dependencies, as a universal test. After several pilot studies, screening was gradually extended to mainland France in 1996. Since 2000, the test has been performed at national level for all newborns defined as being "at risk" for SCD based on ethnic origin. METHODS: A dry blood sample is obtained by heel stick and analysed by isoelectric focusing as a first-line method, followed by either high-performance liquid chromatography or acid agar electrophoresis for confirmation, whenever a variant haemoglobin is observed on isoelectric focusing. RESULTS: In 2007, 28.45% of all newborns in mainland France were screened for SCD. Since 1996, a total of 3,890 newborns have been found to have SCD, and they have been followed up by reference paediatricians. CONCLUSION: Although screening for SCD at birth in France is not universal, it appears that missed babies are relatively infrequent. Despite obvious sociological problems inherent to the at-risk population, the follow-up of SCD babies is rather successful. Due to the birth prevalence of SCD in France, especially in comparison with other common genetic diseases, screening all newborns regardless of ethnic origin is an issue that is being addressed.


Subject(s)
Anemia, Sickle Cell/diagnosis , Neonatal Screening/methods , Anemia, Sickle Cell/epidemiology , Blood Specimen Collection/methods , Chromatography, High Pressure Liquid , Electrophoresis, Agar Gel , France/epidemiology , Hemoglobinopathies/diagnosis , Hemoglobinopathies/epidemiology , Humans , Infant, Newborn , Isoelectric Focusing
6.
Transfus Clin Biol ; 15(1-2): 39-50, 2008.
Article in English | MEDLINE | ID: mdl-18515167

ABSTRACT

In sickle cell disease, the complex scenario of vaso-occlusive crisis (VOC) typical of this disease is clearly multifactorial and not fully understood. Cell-cell and cell-cell matrix interactions mediated by adhesive molecules present on blood cells and endothelial cells (ECs) are thought to play an important role. Early studies have shown that sickle red blood cells (RBCs) are abnormally adherent to ECs and some of the molecules involved in these interactions have been identified, such as the alpha4beta1 integrin and CD36, exclusively present on stress reticulocytes, and CD47 on mature RBCs. More recently, attention focused on Lu/BCAM, the unique RBC receptor for laminin, and on ICAM-4, a red cell-specific adhesion receptor, which is a ligand for a large repertoire of integrins (alphaLbeta2, alphaMbeta2, alphaxbeta2, alphaVbeta3). The counter-receptors on ECs and the role of plasma proteins forming bridges between blood cells and ECs have been clarified in part. It has also been shown that reticulocytes from SCD patients express higher levels of alpha4beta1 integrin and CD36, and that under hydroxyurea (HU) therapy, both cell adhesion to ECs or extracellular matrix proteins and the levels of these adhesion molecules are reduced. These findings are consistent with the view that enhanced adhesion of blood cells to ECs is largely determined by the membrane expression level of adhesion molecules and could be a crucial factor for triggering or aggravating vaso-occlusion. In SCD patients, membrane expression of Lu/BCAM (and perhaps ICAM-4) is enhanced on RBCs whose adherence to laminin or ECs is also increased. Interestingly, Lu/BCAM- and ICAM-4-mediated adhesion are enhanced by the stress mediator epinephrine through a PKA-dependent pathway initiated by a rise in intracellular cAMP and leading to receptor activation by phosphorylation according to the same signaling pathway. More recently, studies based on quantitative expression analysis of adhesion molecules on RBCs and during erythroid differentiation in patients undergoing HU therapy, surprisingly revealed that Lu/BCAM level was enhanced, although alpha4beta1, CD36 and ICAM-4 (to a lower extent) levels were indeed reduced. CD47 and CD147 expression were also enhanced in HU-treated patients. Based on these findings we suggest that the signalization cascade leading to receptor activation rather than the expression level only of adhesion molecules may be the critical factor regulating cell adhesion, although both mechanisms are not mutually exclusive.


Subject(s)
Anemia, Sickle Cell/physiopathology , Cell Adhesion Molecules/drug effects , Erythrocytes/drug effects , Hydroxyurea/pharmacology , Anemia, Sickle Cell/blood , Anemia, Sickle Cell/pathology , CD36 Antigens/biosynthesis , Cell Adhesion/drug effects , Cell Adhesion/physiology , Child , Erythrocytes/physiology , Humans , Integrin alpha4beta1/biosynthesis
7.
Ann Biol Clin (Paris) ; 63(6): 627-30, 2005.
Article in French | MEDLINE | ID: mdl-16330381

ABSTRACT

Cystic fibrosis is the most frequent autosomal recessive genetic disease in North European population. This pathology seems to not be rare in Tunisia. On another hand, development of molecular biology techniques has largely contributed to implement the study of the different mutations in the CFTR gene where over 1,300 mutations were reported. Herein, we describe the strategy used to detect molecular defects responsible of cystic fibrosis on 390 children (383 families) in Tunisian population. Several techniques were performed for genotype diagnosis: DNA extraction was from peripheral blood. Polymerase chain reaction (PCR) and polyacylamide gel electrophoresis, and reverse dot blot procedures were used to detect known point mutations. Denaturant gradient gel electrophoresis (DGGE) were used in a next step searching for the unknown point mutations that are later identified by automated sequencing on ABIprism 310. This strategy allowed us to detect 17 different mutations located on the different exons of the CFTR gene. The most frequent was the F508del (50.74%) followed by three other mutations (G542X, W1282X and N1303K) known to be common in the Mediterranean area. For mutations (T665S, 2766 del8, F1166C, L1043R) were exclusively found, up to now, in the Tunisian population. Our results permitted to establish cystic fibrosis mutations and their distribution in Tunisia and to implement an appropriate prevention program of these diseases through the genetic council and prenatal diagnosis.


Subject(s)
Cystic Fibrosis/epidemiology , Cystic Fibrosis/genetics , Mutation , Child , Child, Preschool , Humans , Infant , Molecular Epidemiology , Tunisia/epidemiology
8.
Pharmacogenomics J ; 3(4): 215-26, 2003.
Article in English | MEDLINE | ID: mdl-12931135

ABSTRACT

The clinical efficacy of oral hydroxyurea (HU) in adults and children with sickle cell anemia (SCA) cannot solely be explained by its ability to enhance fetal hemoglobin (HbF) expression. Since increased adherence of sickle red blood cells to vascular endothelium is a possible contributing factor to vaso-occlusive crisis (VOC), we explored the effect of HU on human endothelial cell (EC) lines (TrHBMEC and EA-hy 926). We demonstrated that HU, in a dose-dependent and reversible manner, significantly decreased (up to three-fold) the release of endothelin-1 (ET-1), a vasoconstrictor peptide through downregulation (up to three-fold) of ET-1 gene expression. This finding is of therapeutic relevance as SCA patients exhibit elevated serum levels of ET-1 during episodes of VOC and levels correlate with disease severity. Unexpectedly, HU upregulated (up to three-fold) the expression of membrane-bound intercellular cell adhesion molecule 1 (mbICAM-1) and its soluble form (sICAM-1) with a parallel increase in ICAM-1 mRNA expression. Although ICAM-1 does not appear to be involved in the sickle cell adhesion to vascular endothelium, it may exacerbate vaso-occlusion by promoting leukocyte adhesion. The HU-induced increase in mbICAM-1 may appear inconsistent with the clinical benefits confered by HU. However, both the increase in sICAM-1- and HU-induced leukocyte reduction in patients, may counteract the potentially detrimental effect of elevated mbICAM-1 expression. Also HU reduces the expression of vascular cell adhesion molecule (VCAM-1) on EC. Since HU reduces the very late antigen 4-positive reticulocytes in SCA patients, a ligand for VCAM-1, HU-induced downregulation of VCAM-1 on EC will very likely decrease the reticulocyte-endothelium adhesion. Thus, HU, apart from inducing HbF expression in the red cell, also affects the expression profile of EC compartment.


Subject(s)
Antisickling Agents/pharmacology , Endothelial Cells/drug effects , Endothelin-1/genetics , Gene Expression/drug effects , Hydroxyurea/pharmacology , Intercellular Adhesion Molecule-1/genetics , Anemia, Sickle Cell/drug therapy , Cell Line , Dose-Response Relationship, Drug , Down-Regulation , Endothelial Cells/metabolism , Endothelin-1/biosynthesis , Flow Cytometry , Humans , Intercellular Adhesion Molecule-1/biosynthesis , RNA, Messenger/biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , Up-Regulation
10.
Arch Pediatr ; 8(8): 843-52, 2001 Aug.
Article in French | MEDLINE | ID: mdl-11524916

ABSTRACT

Despite significant progress in intensive care medicine, the mortality of septic shock has not changed in recent years. Early recognition of subtle signs in favor of meningococcal sepsis, early antibiotic treatment, and aggressive hemodynamic support remains the cornerstone of therapy of severe meningococcal shock in children. Recent work has emphasized the role of genetic polymorphisms in various systems to explain the most severe cases: anti-inflammatory cytokine profile IL-10/TNF-alpha, elevated levels of plasminogen activator inhibitor type-1, variants of the gene for mannose-binding lectin complement pathway. This may explain the disillusionment of pediatric intensivists, and the general failure of immunotherapy for sepsis. Reasonable hope lies upon new meningococcal vaccines.


Subject(s)
IgA Vasculitis/physiopathology , Meningococcal Infections/complications , Polymorphism, Genetic , Shock, Septic/physiopathology , Child , Coagulation Protein Disorders/complications , Cytokines/genetics , Cytokines/pharmacology , Genetic Predisposition to Disease , Humans , IgA Vasculitis/genetics , Shock, Septic/genetics
11.
Eur J Hum Genet ; 9(8): 577-82, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11528502

ABSTRACT

Mutations in the MUT locus encoding for the methylmalonyl-CoA mutase (MCM) apoenzyme are responsible for the mut forms of methylmalonic acidemia (MMA). To date, 49 different mutations have been identified in mut MMA. Only two frequent mutations have been reported in the Japanese population and in African-Americans. Here we report a new missense mutation N219Y (731 A-->T) which we found in five unrelated families of French and Turkish descent. All the patients exhibited a severe mut(degree) phenotype and three of them were homozygotes for N219Y. Direct involvement of the mutation in the loss of enzyme activity was demonstrated by mutagenesis and transient expression study. Mapping of the mutation onto a three-dimensional model of human MCM constructed by homology with the Propionibacterium shermanii enzyme shows that it lies in a highly conserved secondary structure motif and might suggest impaired folding and/or poor stability compatible with the mut(degree) phenotype. Finally, a 1% N219Y carrier frequency was observed in a French anonymous control population. Thus, N219Y is the first frequent mut mutation to be reported in the Caucasian population.


Subject(s)
Amino Acid Substitution/genetics , Lipid Metabolism, Inborn Errors/genetics , Methylmalonic Acid/blood , Mutation, Missense/genetics , White People/genetics , Amino Acid Sequence , Asparagine/genetics , Child , Child, Preschool , Female , Humans , Infant , Lipid Metabolism, Inborn Errors/blood , Lipid Metabolism, Inborn Errors/enzymology , Male , Methylmalonic Acid/metabolism , Methylmalonyl-CoA Mutase/genetics , Methylmalonyl-CoA Mutase/metabolism , Molecular Sequence Data , Tyrosine/genetics
12.
Blood ; 98(4): 1261-3, 2001 Aug 15.
Article in English | MEDLINE | ID: mdl-11493481

ABSTRACT

This study identified and characterized a novel delta beta fusion gene in which the delta-globin gene promoter is linked to intact beta-globin coding sequences in a Senegalese family. It results from a 7.4-kb deletion that removes the delta-globin coding sequences, the delta beta intergenic region as well as the beta-globin gene promoter and causes delta(0)beta(+) thalassemia with hemoglobin A expressed at the 11% to 15% range. The phenotype of this naturally occurring delta beta hybrid gene not only clarifies, in an in vivo context, the respective strength of delta- and beta-globin gene promoters, but also emphasizes the importance of beta-globin intragenic sequences in the expression of beta-globin chains. (Blood. 2001;98:1261-1263)


Subject(s)
Hemoglobin A/genetics , Hemoglobins, Abnormal/genetics , Sequence Deletion/genetics , Adolescent , Adult , Child , Child, Preschool , Family Health , Female , Globins/genetics , Humans , Male , Middle Aged , Nuclear Family , Pedigree , Promoter Regions, Genetic/genetics , Senegal , beta-Thalassemia/genetics
13.
Arch Pediatr ; 8(5): 474-80, 2001 May.
Article in French | MEDLINE | ID: mdl-11396106

ABSTRACT

UNLABELLED: We report a five-year experience of targeted neonatal screening for sickle cell disease in the northern part of the Paris area as well as the follow-up procedure of screened patients. POPULATION: This geographic area in France is characterized by a high frequency of populations at risk for sickle cell disease. RESULTS: Among 115,480 tested newborns, 250 patients were diagnosed (frequency: 1/462). The quality of the screening was attested by the high frequency (5.34%) of newborn carriers for a hemoglobin abnormality (n = 6168). We developed an optimized strategy which avoids the majority of pitfalls (false positive and false negative responses), except for S/HPFH. More than 95% of sickle cell disease was followed, the majority by medical sickle cell disease experts from hospitals. Only two deaths were recorded during this time period. CONCLUSION: We demonstrate the efficiency of targeting the proposed methodological strategy and the follow-up of affected newborns, a major argument demonstrating the importance of newborn screening.


Subject(s)
Anemia, Sickle Cell/diagnosis , Mass Screening , Anemia, Sickle Cell/epidemiology , False Positive Reactions , Female , France/epidemiology , Humans , Incidence , Infant, Newborn , Male , Urban Population
14.
Clin Chem Lab Med ; 39(2): 90-108, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11341756

ABSTRACT

Pulmonary surfactant is a multimolecular complex located at the air-water interface within the alveolus to which a range of physical (surface-active properties) and immune functions has been assigned. This complex consists of a surface-active lipid layer (consisting mainly of phospholipids), and of an aqueous subphase. From discrete surfactant sub-fractions one can isolate strongly hydrophobic surfactant proteins B (SP-B) and C (SP-C) as well as collectins SP-A and SP-D, which were shown to have specific structural, metabolic, or immune properties. Inborn or acquired abnormalities of the surfactant, qualitative or quantitative in nature, account for a number of human diseases. Beside hyaline membrane disease of the preterm neonate, a cluster of hereditary or acquired lung diseases has been characterized by periodic acid-Schiff-positive material filling the alveoli. From this heterogeneous nosologic group, at least two discrete entities presently emerge. The first is the SP-B deficiency, in which an essentially proteinaceous material is stored within the alveoli, and which represents an autosomal recessive Mendelian entity linked to the SFTPB gene (MIM 1786640). The disease usually generally entails neonatal respiratory distress with rapid fatal outcome, although partial or transient deficiencies have also been observed. The second is alveolar proteinosis, characterized by the storage of a mixed protein and lipid material, which constitutes a relatively heterogeneous clinical and biological syndrome, especially with regard to age at onset (from the neonate through to adulthood) as well as the severity of associated signs. Murine models, with a targeted mutation of the gene encoding granulocyte macrophage colony-stimulating factor (GM-CSF) (Csfgm) or the beta subunit of its receptor (II3rb1) support the hypothesis of an abnormality of surfactant turnover in which the alveolar macrophage is a key player. Apart from SP-B deficiency, in which a near-consensus diagnostic chart can be designed, the ascertainment of other abnormalities of surfactant metabolism is not straightforward. The disentanglement of this disease cluster is however essential to propose specific therapeutic procedures: repeated broncho-alveolar lavages, GM-CSF replacement, bone marrow grafting or lung transplantation.


Subject(s)
Metabolism, Inborn Errors/genetics , Metabolism, Inborn Errors/metabolism , Pulmonary Surfactants/genetics , Pulmonary Surfactants/metabolism , Adult , Animals , Base Sequence , DNA/genetics , Female , Humans , Hyaline Membrane Disease/genetics , Hyaline Membrane Disease/metabolism , Infant, Newborn , Male , Mice , Mutation , Pedigree , Proteolipids/genetics , Proteolipids/metabolism , Pulmonary Alveolar Proteinosis/genetics , Pulmonary Alveolar Proteinosis/metabolism , Pulmonary Surfactants/chemistry , Pulmonary Surfactants/deficiency
15.
J Med Screen ; 8(1): 8-14, 2001.
Article in English | MEDLINE | ID: mdl-11373853

ABSTRACT

BACKGROUND: The French national programme for the neonatal screening of sickle cell disease (SCD) was set up in 1995. This screening is targeted at newborn infants at risk. Over 5 years, 115,480 newborn infants were tested from 80 maternity departments from the northern part of the Paris area. 250 Patients with SCD were identified--that is, one in 462 newborn infants tested. Carriers for a haemoglobin (Hb) variant are frequent (5.34%). Some uncommon Hb variants were also identified, which gave rise to pitfalls to the testing when associated with HbS: HbKorle-Bu, HbHope, HbBougardirey-Mali, and HbLadésirade (4% of SS-like profiles). OBJECTIVE: An effective screening strategy was developed to avoid these false positive and false negative responses. METHODS: Isoelectric focusing (IEF), the method of primary screening, is rapid and inexpensive. Cation exchange high performance liquid chromatography (CE-HPLC), which is automated, fast, and quantitative was selected as a secondary method. RESULTS: IEF diagnosed normal profiles in 89% of the tested samples from newborn infants. CE-HPLC identified most of the common Hb variants by their retention time and the measure of HbA/HbS ratio, important for the differential diagnosis between an asymptomatic HbS carrier and an HbS/beta+thal compound heterozygote. Furthermore, the high sensitivity of the CE-HPLC detected as little as 0.5% of a Hb variant. This avoided false negatives in samples from premature or transfused newborn infants. All samples with SS-like profiles were confirmed with a second CE-HPLC with another programme. A combination of these three methods confirmed the status of 99.7% of the samples from the tested newborn infants. Some cases required a reverse phase-HPLC method (for gamma-globin or alpha-globin chain variants). Finally, some exceptional samples required confirmation by testing DNA extracted with Güthrie paper for a precise diagnosis. CONCLUSIONS: This effective strategy combining several methods dramatically reduces the risk of errors. Many families are thus spared unnecessary worrying recalls. The only unavoidable cause of false positives remains the HbS/hereditary fetal Hb (HPFH).


Subject(s)
Anemia, Sickle Cell/diagnosis , Neonatal Screening/methods , Anemia, Sickle Cell/blood , Anemia, Sickle Cell/genetics , Base Sequence , Chromatography, High Pressure Liquid , Chromatography, Ion Exchange , Diagnostic Errors , Genetic Carrier Screening , Genetic Testing/methods , Genetic Variation , Hemoglobin, Sickle/genetics , Hemoglobin, Sickle/isolation & purification , Humans , Infant, Newborn , Oligonucleotide Probes/genetics , Paris , Sensitivity and Specificity
16.
Ann Biol Clin (Paris) ; 59(2): 131-48, 2001.
Article in French | MEDLINE | ID: mdl-11282516

ABSTRACT

Pulmonary surfactant is a multimolecular complex located at the air-water interface within the alveolus and to which a bulk of functions has been assigned, physical (surface-active properties) as well as immune or depurant. This complex consists of a surface active lipid layer (mainly phospholipids), and of an aqueous subphase. From discrete surfactant sub-fractions, one can isolate very hydrophobic proteins SP-B and SP-C as well as the collectins SP-A and SP-D, which were shown to have structural, metabolic, or defensive properties. Inborn or acquired abnormalities of surfactant, qualitative or quantitative in nature, account for a number human diseases. Beside hyaline membrane disease of the preterm neonate, a cluster of hereditary or acquired lung diseases have been characterized by the storage of periodic acid Schiff-positive material filling the alveoli. From this heterogeneous nosologic bulk, at least two discrete entities presently seem to emerge: 1) SP-B deficiency, in which an essentially proteinaceous material is stored within the alveoli, and which is a bona fide autosomal recessive Mendelian entity linked to the SFTPB gene (MIM 1786640), generally entailing neonatal respiratory distress with rapid fatal outcome, although partial or transient deficiencies have also been observed; 2) alveolar proteinosis, characterized by the storage of a mixed, protein and lipid material, and which constitutes a relatively heterogeneous clinical biological syndrome, with regards to age at onset (from the neonate through to adulthood) as well as the severity of associated signs. Murine models with a targeted mutation of the gene encoding GM-CSF (Csfgm) or the beta subunit of its receptor (Il3rbl) support the hypothesis of an abnormality of surfactant turnover in which the alveolar macrophage would be a key player. Beside SP-B deficiency, in which a near-consensus diagnostic chart can be designed, the ascertainment of other abnormalities of surfactant metabolism is not straightforward. The disentanglement of this disease cluster is however essential, with aim to propose differentiated therapeutic procedure : repeated bronchoalveolar lavages, GM-CSF replacement, bone marrow grafting or lung transplantation.


Subject(s)
Amino Acid Metabolism, Inborn Errors/genetics , Genetic Heterogeneity , Proteolipids/genetics , Pulmonary Alveolar Proteinosis/congenital , Pulmonary Alveolar Proteinosis/genetics , Pulmonary Surfactants/deficiency , Pulmonary Surfactants/genetics , Amino Acid Metabolism, Inborn Errors/diagnosis , Amino Acid Metabolism, Inborn Errors/therapy , Animals , Biopsy , Bone Marrow Transplantation , Bronchoalveolar Lavage Fluid , Diagnosis, Differential , Disease Models, Animal , Genes, Recessive/genetics , Genotype , Granulocyte-Macrophage Colony-Stimulating Factor/genetics , Granulocyte-Macrophage Colony-Stimulating Factor/therapeutic use , Humans , Lung Transplantation , Macrophages, Alveolar , Mice , Molecular Biology , Mutation/genetics , Proteolipids/chemistry , Pulmonary Alveolar Proteinosis/diagnosis , Pulmonary Alveolar Proteinosis/therapy , Pulmonary Surfactants/chemistry
17.
Haematologica ; 86(2): 142-5, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11224482

ABSTRACT

BACKGROUND AND OBJECTIVES: The majority of the chromosomes with the betaS gene have one of the five common haplotypes, designated as Benin, Bantu, Senegal, Cameroon, and Arab-Indian haplotypes. However, 5-10% of the chromosomes have less common haplotypes, usually referred to as atypical haplotypes. We have demonstrated that most atypical haplotypes are generated by recombinations. The present study was carried out in order to explore whether recombination also occurs in chromosomes with the common (or typical) haplotypes. DESIGN AND METHODS: We screened the HS-2 region of the beta-globin gene locus control region (LCR) in 244 sickle cell patients who had typical restriction fragment length polymorphism (RFLP)-defined haplotypes of the betaS-gene cluster. For 14 cases in which the expected and the observed LCR repeat-sequence sizes were discrepant, the analysis was extended to other unexplored polymorphic markers of the bS-globin gene cluster, i.e.: pre-Ggamma framework, pre-Ggamma 6-bp deletion, HS-2 LCR (AT)xR(AT)y and pre-beta(AT)xTy repeats, and the intragenic beta-globin gene framework. RESULTS: In all 14 cases (15 chromosomes) in which the LCR repeat-sequence sizes were discrepant, a recombination involving a typical 3' segment of the betaS globin gene cluster was demonstrated. In most of the cases, the recombination site was located between the beta-globin gene and the betaLCR. Nine cases involving recombination were detected among 156 Brazilian HbS homozygotes and five among 88 African patients homozygotes for the Benin haplotype. INTERPRETATION AND CONCLUSIONS. Thus, 3.1% of apparently typical haplotypes linked to the sickle cell gene involve recombinations similar to those that generate the atypical haplotypes, a finding that reinforces the picture of the beta-globin gene cluster as highly dynamic.


Subject(s)
Gene Rearrangement , Globins/genetics , Hemoglobin, Sickle/genetics , Africa/epidemiology , Anemia, Sickle Cell/blood , Anemia, Sickle Cell/genetics , Brazil/epidemiology , Haplotypes , Humans , Multigene Family , Recombination, Genetic
18.
Mol Genet Metab ; 72(2): 181-4, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11161845

ABSTRACT

Inherited defects in the gene encoding the methylmalonyl-CoA mutase (MCM) result in the mut forms of methylmalonic aciduria (MMA). Twelve mutations have been identified associated with the mut(-) phenotype. We report two novel mutations (K621N and D156N) in a compound heterozygote mut(-) patient. These two mutations and three previously published ones (H627N, A191E, Y231N) were mapped onto a three-dimensional homology model of the human MCM constructed from the crystal structure of the Propionibacterium shermanii enzyme.


Subject(s)
Acyl Coenzyme A/chemistry , Acyl Coenzyme A/deficiency , Acyl Coenzyme A/genetics , Mutation, Missense , Mutation , Child, Preschool , Female , Genotype , Heterozygote , Humans , Models, Molecular , Molecular Sequence Data , Mutagenesis , Phenotype , Propionibacterium/enzymology , Protein Structure, Tertiary
19.
Cell ; 103(5): 711-21, 2000 Nov 22.
Article in English | MEDLINE | ID: mdl-11114328

ABSTRACT

Mutation and subsequent recombination events create genetic diversity, which is subjected to natural selection. Bacterial mismatch repair (MMR) deficient mutants, exhibiting high mutation and homologous recombination rates, are frequently found in natural populations. Therefore, we have explored the possibility that MMR deficiency emerging in nature has left some "imprint" in the sequence of bacterial genomes. Comparative molecular phylogeny of MMR genes from natural Escherichia coli isolates shows that, compared to housekeeping genes, individual functional MMR genes exhibit high sequence mosaicism derived from diverse phylogenetic lineages. This apparent horizontal gene transfer correlates with hyperrecombination phenotype of MMR-deficient mutators. The sequence mosaicism of MMR genes may be a hallmark of a mechanism of adaptive evolution that involves modulation of mutation and recombination rates by recurrent losses and reacquisitions of MMR gene functions.


Subject(s)
Adenosine Triphosphatases , Base Pair Mismatch , DNA Repair , DNA-Binding Proteins , Escherichia coli Proteins , Evolution, Molecular , Alleles , Bacterial Proteins/genetics , Escherichia coli/genetics , Exodeoxyribonuclease V , Exodeoxyribonucleases/genetics , Genotype , MutL Proteins , MutS DNA Mismatch-Binding Protein , Mutation , Phenotype , Phosphoric Monoester Hydrolases/genetics , Phylogeny , Polymerase Chain Reaction , Pyrophosphatases , Recombination, Genetic , Salmonella typhimurium/genetics
20.
J Soc Biol ; 194(1): 9-13, 2000.
Article in French | MEDLINE | ID: mdl-11107543

ABSTRACT

Pharmacogenetics and ecogenetics constitute the study of the contribution of genetic factors in interindividual variations in drugs and xenobiotics metabolism respectively and also its physiopathology (toxicity, therapeutic failure and pejorative effect). However, the frontiers between these two fields are interpenetrant with no defined limits. Among the enzymes involved in transformation of drugs/xenobiotics, the cytochrome P450 superfamily plays a major role. Most of the "poor metabolisers" either homozygotes or compound heterozygotes for mutant cytochrome P450 alleles have no detectable enzyme activity. Although phenotyping using a marker drug is usefull, it suffers from several constraints and is influenced by several environmental factors and physiopathological state of the individual. To overcome not only these difficulties but also to improve the overall predictiveness of a drug biotransformation, genotype technology offers an advantage and pharmaco-economic technology further expands the horizon. These fast moving fields must, in near future, allow tailoring of drug prescription on a personalized basis and should, in principle, help in the design and development of novel drug molecules.


Subject(s)
Biotransformation/genetics , Pharmacogenetics , Cytochrome P-450 CYP2D6/genetics , Cytochrome P-450 CYP2D6/physiology , Cytochrome P-450 Enzyme System/classification , Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/physiology , Drug Hypersensitivity/genetics , Drug-Related Side Effects and Adverse Reactions , Forecasting , Genetic Variation , Genotype , Humans , Inactivation, Metabolic/genetics , Isoenzymes/genetics , Isoenzymes/physiology , Microsomes, Liver/enzymology , Pharmacokinetics , Phenotype , Xenobiotics/pharmacokinetics
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