Duffy Genotype and Clinical Manifestations Severity in Sickle Cell Anemia / Genótipo Duffy e Gravidade das Manifestações Clínicas na Anemia Falciforme

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

23/03/2011

RESUMO

INTRODUCTION: Sickle cell anemia (SCA) presents with large clinical variability and previous studies suggest that genetic polymorphisms may act as complications predictors. The Duffy antigen appears to play an important role in the removal of inflammatory chemokines from the circulation, suggesting that Duffy-Negative individuals have lower clearance of cytokines and increased endothelial injury. OBJECTIVES: To determine the frequency of Duffy phenotype, determine the allelic frequency of gene DUFFY, correlate the phenotypic findings with the genotype and determine the importance of the Duffy phenotype in clinical and laboratory data from a group of SCA patients. PATIENTS: 90 AF patients regularly followed in the outpatient clinic of Hemoglobinophaties of the Department of Hematology, Federal University of Sao Paulo (UNIFESP / EPM). METHODS: Erytrocyte phenotyping of Duffy blood group was performed by hemagglutination in gel and molecular analysis of DUFFY gene was performed with specific PCR primers followed by digestion with restrition enzymes. We analyzed the rs12075 polymorphism (125 G>A) that identifies the alleles FY*A and FY*B; mutations: rs2814778 (-33 T>C) that characterizes the allele FY*B-33, and rs34599082 (265 C>T) and rs13962 (298G>A) that identify the alleles FY*Bweak. These individuals were stratified according to the phenotype, in Duffy-Positive [Fy (a+b-), Fy (a+b+) and Fy (a-b+)] and Duffy-Negative [Fy(ab-)]. Through medical records review, we evaluated baseline hemoglobin (Hb), fetal hemoglobin (HbF), S hemoglobin (HbS), reticulocytes count, serum lactate dehydrogenase (LDH), ulcers of the lower limbs (UMI), priapism, acute chest syndrome episodes (STA), osteonecrosis (ON), elevated pulmonary arterial pressure (PAP . 30 mmHg), stroke (history and neuroimaging) and indication of use of hydroxyurea (HU). Statistical analysis was performed with Mann-Whitney and Fisher tests, with a significance level of 5%. RESULTS: 40% of the patients were male, median age was 30.04 } 10.15 years. Phenotypic analysis revealed 73.3% Duffy-Positive and 26.7% Duffy-Negative individuals. The allele FY*B was found in 71% of the patients, and the FY*B-33 allele was found in 43% of the FY*B alleles. Duffy-Negative patients had a mean Hb of 8.32 g/dL, while Duffy-Positive the mean Hb was 9.01 g/dL (p = 0.039). There were no differences in the reticulocyte count, Hb, HbF withing the groups. However, the mean DHL was 634.59 U/L in Duffy-Negative individuals and 506.42 U/L in Duffy-Positive (p=0.045). 63.6% of Duffy-Negative individuals and 31.5% in Duffy-Positive showed elevated PAP (p = 0.0118, odds ratio: 3.792, 95% confidence interval: 1.350 to 10.652). There were no statistical differences in priapism, ON, STA and UMI frequencies of amoung groups. Stroke was observed only in Duffy-Positive patients (p=0.0049, odds ratio: 0.0625, 95% Confidence Interval: 0.0035 to 1.089). Indications of HU use was higher in Duffy-Positive subjects (p=0.0528, odds ratio: 0.3524, 95% Confidence Interval: 0.1278 to 0.9717). CONCLUSION: Given the results above, we can infer that the presence of the studied mutations is strongly associated with expression of the Duffy antigens. From clinical and laboratory data viewpoint, although Duffy-Negative individuals had a greater frequency of PAP, its rate of use of HU is smaller and therefore one can not say that they had a worse clinical outcome. Thus, further studies, preferably multicenter, are needed to clarify this issue.

ASSUNTO(S)

polimorfismos gênicos anemia falciforme sistema do grupo sanguíneo duffy antígenos de grupos sanguíneos genótipo hematologia

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