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BACKGROUND: The mannose-binding lectin (MBL) plays an important role in innate immunity. Genetically determined variations in serum levels of MBL may influence the susceptibility and clinical outcome of dengue infection in early life. METHODS: We investigated the MBL2 gene polymorphisms and serum levels of MBL (total and functional) in children with asymptomatic (n=17) and symptomatic (n=29) primary dengue infections and age-matched uninfected children (n=84) enrolled in a birth cohort with dengue in Brazil. Polymorphisms of the MBL2 gene were assessed by reverse transcription-polymerase chain reaction (RT-PCR), whereas the enzyme-linked immunosorbent assay (ELISA) was used to quantify serum levels of MBL. RESULTS: We found that the X allele and YX genotype in the MBL2 were more frequent in the dengue cases than in the control group. Likewise, the LXPA haplotype was exclusively found in dengue cases, thus probably related to dengue infection in our setting. Moreover, we found a higher frequency of the O allele and AO genotype in the control group. Serum levels of total and functional MBL were higher in dengue naïve infants than in dengue cases. CONCLUSIONS: MBL2 variants related to lower production of serum MBL were associated with dengue infection in infants, whereas intermediate to high levels of total and functional serum MBL were associated with protection against dengue infection. These findings highlight the role of MBL2 variants and serum levels of MBL in the susceptibility of children to dengue disease at early ages.
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Dengue , Lectina de Ligação a Manose , Brasil/epidemiologia , Criança , Dengue/epidemiologia , Dengue/genética , Predisposição Genética para Doença , Genótipo , Haplótipos , Humanos , Lactente , Lectina de Ligação a Manose/genética , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Background: The mannose-binding lectin (MBL2) and nitric oxide synthase 3 (NOS3) genes are associated with the immune response against inflammatory processes, have been reported as possibly related with premature birth. Until now, most of the researches regarding the genetic influence of prematurity have revealed limited results because only investigating the child or the mothers' genotypes, thus not exploring the possible effects of interactions between these genotypes or the interactions with environmental factors related to the duration of pregnancy.Objective: We performed a replica study investigating the influence of single nucleotide polymorphisms (SNPs) in MBL2 and NOS3 genes on premature birth, also considering socioeconomic, demographic, and gestational factors.Materials and methods: We conducted a case-control study with 189 mother-infant dyads, with 104 spontaneous preterm births and 85 term births from Recife, Brazil. We used peripheral blood samples and umbilical cord samples to extract DNA. Functional SNPs at exon 1 and promoter region of MBL2 and NOS3 RS1799983 SNP were genotyped using direct sequencing and fluorescent allelic specific TaqMan® assays respectively. Data were analyzed using the Statistical Package for the Social Sciences (SPSS®) program with bivariate association and logistic multivariate regression tests.Results: We observed a prevalence of MBL2 wild-type genotype in the mother-infant dyad of the preterm group and polymorphic genotype in the mother-infant dyad of term birth. The haplotype LYA predominated in our sample, being more frequent in the preterm group, while the haplotype LYB, correlated with lower levels of MBL protein, was more frequent in the term birth group. About NOS3 RS1799983 SNP, the G/G genotype was more frequent throughout the sample. The heterozygous genotype predominated among women from the preterm group, showed a borderline difference between the groups. When MBL2 genotypes of the mother and son were analyzed together, codon 54 of MBL2 remained associated with prematurity. When the variables with p value lower than .20 in the bivariate analysis were analyzed by logistic regression, the low weight of the pregnant woman in relation to the gestational age, the occurrence of preterm premature rupture of membranes, urinary tract infection during birth and maternal history of other premature births were risk factors to prematurity. On the other hand, the presence of B allele at codon 54 of maternal MBL2 was a protective factor for the occurrence of spontaneous premature birth. In contrast, a borderline association was established between the maternal genetic variation within NOS3 gene and the outcome studied.Conclusions: Our study, limited by the small number of patients enrolled, indicates that MBL2 and NOS3 functional SNPs are associated with the occurrence of spontaneous prematurity and the regulation of the maternal inflammatory response. Despite these results are in agreement with previously reports, our findings do not replicate the ones reported in a large genome-wide association study performed on quite high number of subjects. Thus, we can conclude that MBL2 and NOS3 functional SNPs are plausible candidate risk factors just in few preterm birth cases, and consequently they cannot be included in the general diagnostic practice.
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Lectina de Ligação a Manose/genética , Óxido Nítrico Sintase Tipo III/genética , Polimorfismo de Nucleotídeo Único , Nascimento Prematuro/genética , Adolescente , Adulto , Brasil/epidemiologia , Estudos de Casos e Controles , Feminino , Frequência do Gene , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Recém-Nascido , Gravidez , Nascimento Prematuro/epidemiologia , Adulto JovemRESUMO
BACKGROUND Dengue is an arthropod-borne viral disease with a majority of asymptomatic individuals and clinical manifestations varying from mild fever to severe and potentially lethal forms. An increasing number of genetic studies have outlined the association between host genetic variations and dengue severity. Genes associated to viral recognition and entry, as well as those encoding mediators of the immune response against infection are strong candidates for association studies. OBJECTIVES The aim of this study was to investigate the association between MBL2, CLEC5A, ITGB3 and CCR5 genes and dengue severity in children. METHODS A matched case-control study was conducted and 19 single nucleotide polymorphisms (SNPs) were investigated. FINDINGS No associations were observed in single SNP analysis. However, when MBL2 SNPs were combined in haplotypes, the allele rs7095891G/rs1800450C/ rs1800451C/rs4935047A/rs930509G/rs2120131G/rs2099902C was significantly associated to risk of severe dengue under α = 0.05 (aOR = 4.02; p = 0.02). A second haplotype carrying rs4935047G and rs7095891G alleles was also associated to risk (aOR = 1.91; p = 0.04). MAIN CONCLUSIONS This is the first study to demonstrate the association between MBL2 haplotypes and dengue severity in Brazilians including adjustment for genetic ancestry. These results reinforce the role of mannose binding lectin in immune response to DENV.
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Humanos , Receptores CCR5 , Cristalização , Dengue/epidemiologia , AedesRESUMO
BACKGROUND: Host genetic factors such as MBL2 gene polymorphisms cause defects in the polymerization of MBL protein and result in a functional deficiency and/or in low serum levels that can influence susceptibility to various viral infections. The aim of this study was to estimate the frequency of alleles, genotypes and haplotypes related to -550, -221 and exon 1 polymorphisms of the MBL2 gene and investigate their association with HHV-8 in people living with HIV/AIDS (PLWHA), as well as the impacts on CD4 cell count and HIV viral load in HIV/HHV-8 coinfected and HIV monoinfected patients. RESULTS: A cross sectional study in PLWHA, with and without HHV-8 infection, exploring associations between different factors, was performed in the outpatient infectious and parasitic diseases clinic at a referral hospital. Genomic DNA extractions from leukocytes were performed using a commercial Wizard® Genomic DNA Purification kit (Promega, Madison, WI). The promoter region (-550 and -221) was genotyped with the TaqMan system (Applied TaqMan Biosystems® genotyping Assays), and the structural region (exon1) was genotyped with Express Sybr Greener Supermix kit (Invitrogen, USA). In total, 124 HIV/HHV-8 coinfected and 213 HIV monoinfected patients were analysed. Median TCD4 counts were significantly lower in HIV/HHV-8 coinfected patients, whereas the mean of the first and last viral load of HIV did not present significant difference. There was no difference in frequency between the LL, YY and AA genotypes between the HIV/HHV-8 coinfected or HIV monoinfected patients. However, in a multivariate analysis, coinfected patients with the intermediate expression haplotype of the MBL2 gene had an odds ratio of 3.1-fold (CI = 1.2-7.6) of their last CD4 cell count being below 350 cells/mm3. Among the coinfected individuals, four developed KS and presented the intermediate expression MBL haplotype, with three being HYA/LXA and one being LYA/LYO. CONCLUSIONS: Host genetic factors, such as -550, -221 and exon 1 polymorphisms, can be related to the may modify coinfections and/or to the development clinical manifestations caused by HHV-8, especially in HIV/HHV-8 coinfected patients who present the intermediate expression haplotypes of MBL.
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Infecções por Herpesviridae/genética , Lectina de Ligação a Manose/genética , Polimorfismo de Nucleotídeo Único , Adulto , Alelos , Contagem de Linfócito CD4 , Estudos Transversais , Feminino , Predisposição Genética para Doença , Genótipo , Infecções por HIV/virologia , Haplótipos , Infecções por Herpesviridae/virologia , Herpesvirus Humano 8 , Humanos , Masculino , Pessoa de Meia-Idade , Regiões Promotoras Genéticas , Carga ViralRESUMO
Leprosy is a chronic infectious disease caused by Mycobacterium leprae. Genetic factors associated with immune response contribute to infection development and disease. M. leprae has the capacity to invade Schwann cells in the peripheral nervous system and cause neuropathy. However, while the responsible molecular mechanisms remain to be fully unveiled, they have begun being elucidated. We studied genetic variants Myelin Protein Zero (MPZ), a major structural component of the myelin sheath, and Mannose Binding Lectin 2 (MBL2), a protein involved in immune response, in 112 family groups of 114 leprosy patients using PCR-RFLP, aiming to calculate the association and allelic transmission of variants associated in first, second and third-degree relatives. Polymorphisms found in MPZ and MBL2 showed association with leprosy. Different probabilities for allelic transmission were found for first and second-degree relatives, a fact that is important to take into account when evaluating risk in contacts of leprosy patients. Structural analysis allows the study of putative amino acids and their possible effect on protein structure and function, as well as on the assembly of a protein homotetramer. Our results suggest that the identified MPZ and MBL2 gene mutations are associated with leprosy in a Colombian population, which correlates with MPZ and MBL2 protein function, and increase the risk of M. leprae infection in leprosy-patients' family members. Additionally, structural analyses were carried out specifically for MPZ protein using information available in databases, and analyzing the substitutions in wildtype and mutant protein. The results show significant structural changes, which may be associated to infection and pathogenicity.
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Hanseníase , Lectina de Ligação a Manose , Proteína P0 da Mielina , Adulto , Colômbia , Feminino , Humanos , Hanseníase/genética , Hanseníase/imunologia , Masculino , Lectina de Ligação a Manose/química , Lectina de Ligação a Manose/genética , Lectina de Ligação a Manose/imunologia , Pessoa de Meia-Idade , Modelos Moleculares , Proteína P0 da Mielina/química , Proteína P0 da Mielina/genética , Proteína P0 da Mielina/imunologia , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Abstract Sickle cell anemia (SCA) presents heterogenous clinical manifestations that cannot be explained solely by alterations to hemoglobin (Hb); other components such as endothelial adhesion, thrombosis and inflammation may be involved. The mannose-binding lectin (MBL) has an important role in innate immunity and inflammatory diseases. In this report, we describe an association between MBL2 polymorphism related to low production of serum MBL and the frequency of vasoocclusive events (FVOE) in children ≤ 5 years old with SCA (p = 0.0229; OR 5.55; CI 1.11-27.66). Further studies are needed to explore the role of low MBL2 in the pathophysiology of vasoocclusive events in SCA.
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The mannose-binding lectin (MBL) 2 gene has an important function in the innate immune response and activation of the third pathway of the complement system. Some studies have assessed the association of the MBL2 gene polymorphisms with cervicovaginal infections (CVI); however, there is no information about this association in Mexican women. This study aimed to determine the association between the MBL2 codons 54 and 57 gene polymorphisms with CVI in a sample of Mexican women. Through a cross-sectional study, blood samples and cervicovaginal cultures were obtain from 354 women. MBL2 genotyping was performed by real-time polymerase chain reaction with Taqman probes. Of the 354 women studied, 128 (36.2%) had CVI and 226 (63.8%) were healthy. The frequencies of the C and T variants in codon 54 in women with CVI were 83% and 17%, respectively; whereas the frequencies of these variants in healthy women were 82% and 18%, respectively. The frequencies of variants C/C, C/T, and T/T in women with CVI were 68%, 31%, and 1%, respectively; whereas the frequencies of these variants in healthy women were 68%, 29%, and 3%, respectively. With respect to codon 57, the frequencies of variants C and T were identical in women with CVI and in healthy women (97% and 3%, respectively). The frequencies of variants C/C, C/T, and T/T were identical in women with CVI and in healthy women (94%, 6%, and 0%, respectively). We conclude that MBL2 codons 54 and 57 gene polymorphisms do not associate with CVI in Mexican women.
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Dengue is the main arbovirosis in the tropical and subtropical areas of the world. The majority of infected individuals present an asymptomatic outcome while others progress to dengue fever (DF) or dengue haemorrhagic fever (DHF). Dengue infection evolution to severe outcomes is in part, related to innate immunity response. The MBL2 gene encodes for a pathogen recognition pattern molecule, the mannose-binding lectin (MBL). Variant alleles at promoter and structural regions of the MBL2 are related to serum MBL levels and function. Due to the important inflammatory modulation role of MBL, MBL2 polymorphisms could influence dengue progression. Therefore, this study investigated associations of MBL2 polymorphisms and serum MBL levels in patients with dengue. Genotyping of promoter and structural regions of MBL2 was performed by real-time PCR using Taqman® probes in 161 patients presenting DF or DHF outcome. For the serum MBL determination a commercial ELISA kit was used. The variant OO genotype and O allele were associated with DHF (p=0.008 and p=0.009 respectively). Haplotypes correlated to MBL low levels were associated with DHF (p=0.04). Our results support the hypothesis that patients carrying genotypes or haplotypes of low production of MBL would be more susceptible to DHF.
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Lectina de Ligação a Manose/genética , Dengue Grave/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil , Criança , Pré-Escolar , Progressão da Doença , Feminino , Frequência do Gene , Estudos de Associação Genética , Predisposição Genética para Doença , Genótipo , Humanos , Imunidade Inata/genética , Lactente , Recém-Nascido , Masculino , Lectina de Ligação a Manose/sangue , Pessoa de Meia-Idade , Polimorfismo Genético , Adulto JovemRESUMO
BACKGROUND: There is a considerable variation in the phenotype and course of the disease in cystic fibrosis (CF) even in patients with the same CFTR genotype, suggesting that other factors are important for prognosis. Mannose-binding lectin (MBL) has been proposed as one of these factors. We therefore investigated the influence of MBL2 gene variants on disease severity, age at acquisition of Pseudomonas aeruginosa, and survival in CF patients. METHODS: MBL2 variants were studied in 106 Argentinean pediatric CF patients carrying two severe CFTR mutations. Clinical phenotype was defined according to the Shwachman score and lung function tests. Age at infection with P. aeruginosa and age at death were also recorded. RESULTS: MBL insufficiency was associated with a 3.5-fold risk of having a severe phenotype (CI 95%: 1.2-10.3, p=0.03). It was also associated with an earlier onset of infection with P. aeruginosa (p=0.035). No statistically significant differences were found in FEV1 and survival. CONCLUSIONS: MBL insufficiency was associated with detrimental progression of the disease. These results together with previous findings suggest that the effect of MBL2 expression may be a major determinant of the severity of the clinical phenotype in patients with CF.
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Fibrose Cística/genética , Predisposição Genética para Doença/epidemiologia , Lectina de Ligação a Manose/genética , Polimorfismo Genético , Argentina/epidemiologia , Criança , Pré-Escolar , Estudos de Coortes , Fibrose Cística/mortalidade , Fibrose Cística/fisiopatologia , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Progressão da Doença , Feminino , Genótipo , Humanos , Lactente , Recém-Nascido , Estimativa de Kaplan-Meier , Masculino , Fenótipo , Testes de Função Respiratória , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Taxa de SobrevidaRESUMO
Objetivo Analisar a influência da associação do polimorfismo G54D (rs1800450) do gene MBL2 no diabetes melito gestacional (DMG) quanto à necessidade de tratamento complementar e ocorrência de recém-nascidos grandes para a idade gestacional. Sujeitos e métodos Cento e cinco pacientes com DMG segundo parâmetro da OMS (Organização Mundial da Saúde) foram avaliadas no período de novembro de 2010 a outubro de 2012. As gestantes foram divididas em dois grupos correspondentes à presença (n = 37) ou à ausência (n = 68) do alelo mutante. As variantes do polimorfismo G54D foram identificadas por meio da técnica de polimorfismos de comprimentos de fragmentos de restrição (RFLP). Parâmetros antropométricos e bioquímicos da mãe e do recém-nascido (RN) e a necessidade de terapia complementar associada à dietoterapia foram avaliados como desfechos primários. Resultados Das pacientes analisadas, 35,2% carregavam pelo menos um alelo mutante do polimorfismo G54D. Os dois grupos não apresentaram diferença significativa quanto a ganho de peso, paridade, idade, índice de massa corporal e idade gestacional de chegada à maternidade. Os grupos de pacientes portadoras ou não do alelo mutante não diferiram quanto à necessidade de tratamento complementar à dietoterapia (16,2% vs. 26,7%) respectivamente e à ocorrência de recém-nascidos grandes para a idade gestacional (24,3% vs. 13,2%). Conclusão Nossos dados demonstraram que o polimorfismo G54D do gene MBL2 não teve efeito sobre a ...
Objective To assess the association of the G54D (rs1800450) polymorphism of the gene MBL2 in the gestational diabetes mellitus with the need for additional treatment and the occurrence of large newborns for the gestational age. Subjects and methods One hundred and five patients recruited in Joinville – Brazil were evaluated between November 2010 and October 2012. Pregnant women were divided in two groups correspondents to the presence (n = 37) or absence (n = 68) of the mutant allele. The variants of the polymorphism G54D were identified by restriction fragment lengths polymorphisms (RFLP). Anthropometric and biochemical parameters of the mother and the newborn, and the necessity of additional therapy associated with diet were assessed as the primary outcomes. Results Thirty-five point two percent of the evaluated patients carried at least one mutated allele of G54D polymorphism. There were no significant differences in weight gain, parity, age, body mass index and gestational age of arrival at maternity between the two groups. The groups of patients with or without the mutated allele did not differ in the need for additional treatment associated with diet (16.2% vs. 26.7%) respectively and with the occurrence of large newborns for gestational age (24.3% vs. 13.2%). Conclusion Our data showed that the polymorphism G54D of the gene MBL2 had no effect in the need for additional treatment associated with the diet-based therapy and in the occurrence of large newborns for gestational age in the studied population. Arq Bras Endocrinol Metab. 2014;58(9):900-5 .
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Adulto , Feminino , Humanos , Recém-Nascido , Gravidez , Adulto Jovem , Peso ao Nascer/genética , Diabetes Gestacional/genética , Macrossomia Fetal/genética , Lectina de Ligação a Manose/genética , Polimorfismo Genético/genética , Polimorfismo de Fragmento de Restrição/genética , Alelos , Índice de Massa Corporal , Glicemia/análise , Idade Gestacional , Frequência do Gene/genética , Estudos Prospectivos , Aumento de PesoRESUMO
Variations in genes involved in the immune response pathways may influence the interaction between viruses (such as Human T-lymphotropic virus, HTLV-1) and the host. The mannose binding lectin (MBL) and its associated serine protease type 2 (MASP-2) promote the activation of the lectin pathway of the complement system. As the interaction of complement system with HTLV-1 is not well understood, the MBL2 promoter/exon 1 polymorphisms and a MASP2 missense polymorphism were examined in a Northeast Brazilian population, looking for a possible relationship between these variations and the susceptibility to HTLV-1 infection. The present study describes an association between a polymorphism in the MASP2 gene and susceptibility to HTLV-1 infection, and provides further evidence of an association between the MBL2 gene and HTLV-1 infection. These findings suggest an important role of the complement system activation, via the lectin pathway, in the susceptibility to HTLV-1 infection.
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Predisposição Genética para Doença , Infecções por HTLV-I/genética , Infecções por HTLV-I/imunologia , Lectina de Ligação a Manose/genética , Serina Proteases Associadas a Proteína de Ligação a Manose/genética , Polimorfismo Genético , Adulto , Brasil , Proteínas do Sistema Complemento/imunologia , Éxons , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Regiões Promotoras Genéticas , Adulto JovemRESUMO
The innate immune system represents the first line of host defense against pathogens. Genetics factors regulating the immune responses play a role in the susceptibility to infectious diseases, such as tuberculosis (TB). We analyzed MBL2 promoter and exon 1 functional single nucleotide polymorphisms (SNPs) in a group of 155TB patients and 148 healthy controls in order to evaluate their influence on the onset of infection and TB development. There was no association between MBL2 -550 HL promoter polymorphisms and susceptibility to develop TB, but heterozygous -221 Y/X genotype was significantly more frequent in pulmonary TB patients than controls. Moreover, MBL2 exon 1 O allele, was significantly associated with susceptibility to TB development in general (p=0.023, OR=1.61, 95% CI 1.05-2.49) and pulmonary TB (p=0.0008, OR=2.16, 95% CI 1.35-3.46); C allele at codon 57, as well as A/C genotype, were significantly more frequent in TB patients than in controls. Our results indicate that MBL2 polymorphisms, especially at codon 57, could be considered as risk factors for TB development.
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Predisposição Genética para Doença/genética , Lectina de Ligação a Manose/genética , Adolescente , Adulto , Brasil/epidemiologia , Estudos de Casos e Controles , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Tuberculose Pulmonar/epidemiologia , Tuberculose Pulmonar/genética , Adulto JovemRESUMO
A leishmaniose visceral (LV) ou calazar é uma doença endêmica, crônica, grave e de alta letalidade se não tratada. Os estudos apontam a proteína Lectina Ligante de Manose (MBL), codificada pelo gene MBL2, como uma peça-chave na imunidade inata, dada a sua função no reconhecimento microbiano, na eliminação, inflamação e morte celular. Neste trabalho realizamos um estudo do tipo caso-controle que teve como objetivo investigar a associação entre variantes no gene MBL2 e a suscetibilidade à LV em indivíduos residentes em áreas endêmicas da Ilha de São Luís-MA. A amostra foi constituída por 322 indivíduos, sendo 161 casos com LV, não aparentados, de ambos os sexos, residentes em áreas endêmicas da doença na Ilha de São Luís e 161 controles saudáveis, não infectados e não aparentados da mesma região. A identificação dos casos de LV se deu por meio do contato constante com os principais hospitais e ambulatórios de referência para a doença na cidade. Também foram feitas buscas de pacientes com LV em ambiente domiciliar, a partir de registros da FUNASA-MA. A análise molecular consistiu na genotipagem de 6 variantes localizadas na região promotora [posições -550 (C>G), -221(G>C), +4(C>T)] e codificadora [códons 52 (C>T), 54 (G>A) e 57 (G>A)] do gene MBL2, através da reação em cadeia da polimerase e sequenciamento automático. A dosagem da proteína MBL no soro foi realizada pelo teste de ELISA. Verificamos que os fenótipos MBL dependem do conjunto de alelos presentes no gene MBL2, sendo nítido o efeito que as variantes defectivas causam nos níveis da proteína. Não encontramos diferença significativa entre casos e controles em relação à distribuição dos genótipos MBL2 e dos níveis séricos de MBL. As frequências alélicas das variantes exônicas na amostra total mostram que o alelo A é o mais comum (74,8%) e que os alelos defectivos (B, C e D) se encontram principalmente em heterozigose (36,6%), o que reforça a ideia de que alelos MBL2 defectivos são mantidos na população ...
Visceral leishmaniasis (VL), also known as kalazar, is an endemic, chronic, severe and highly lethal disease when not treated. Studies have shown that the protein Mannose-biding lectin (MBL), encoded by the gene MBL2, is the major player in innate immune system due its role in microbial recognition, elimination and inflammation as well as in the cell death. In the current work, we conducted a case-control study which aimed to investigate the association between variants in the gene MBL2 and the susceptibility to VL in individuals living in endemic areas of the São Luís - MA. 322 individuals participated in this study. Of these, 161 were VL cases being unrelated individuals of both sexes, and inhabitants from endemic areas of the disease in São Luís. The other 161 individuals were uninfected healthy controls, being unrelated and from the same region. The identification of VL cases occurred by visiting reference hospitals and clinics in the city. VL patients were identified in the household environment through the records of FUNASA-MA. Molecular analysis consisted in genotyping six variants located in the promoter region [positions -550 (C> G), -221 (G> C), +4 (C> T)] and coding region [codons 52 (C> T), 54 (G> A) and 57 (G> A)] of the MBL2 gene by polymerase chain reaction and automated DNA sequencing. The concentrations of MBL protein in the serum was performed by ELISA. We found that MBL phenotypes depend on the number of alleles present in the gene MBL2, being clear the consequence of the defective variants in the protein levels. There was no significant difference between cases and controls regarding the distribution of MBL2 genotypes and MBL serum levels. The allele frequencies of exon variants in the overall sample showed that the A allele is the most common (74.8%) and that the defective alleles (B, C and D) are mainly heterozygous (36.6%). This highlights the idea that defective MBL2 alleles are maintained in the population to confer selective ...