RESUMO
Thalassemias are pathologies that derive from genetic defects of the globin genes. The most common defects among the population affect the genes that are involved in the synthesis of alpha and beta chains. The main aspects of these pathologies are well explained from a biochemical and genetic point of view. The diagnosis is fundamentally based on hematologic and genetic tests. A genetic analysis is particularly important to determine the carriers of alpha-thalassemia, whose identification by means of the hematologic parameters is more difficult in comparison with heterozygotes for alpha-thalassemia. This work investigates the use of artificial neural networks (ANNs) for the classification of thalassemic pathologies using the hematologic parameters resulting from hemochromocytometric analysis only. Different combinations of ANNs are reported, which allow thalassemia carriers to be discriminated from normals with 94% classification accuracy, 92% sensitivity, and 95% specificity. On the basis of these results, an automated system that allows real-time support for diagnoses is proposed. The automated system interfaces a hemochromo analyzer to a simple PC.
Assuntos
Sistemas Inteligentes , Redes Neurais de Computação , Talassemia alfa/diagnóstico , Talassemia beta/diagnóstico , Adolescente , Técnicas de Apoio para a Decisão , Contagem de Eritrócitos , Índices de Eritrócitos , Feminino , Hematócrito , Hemoglobinas/análise , Humanos , Masculino , Sensibilidade e Especificidade , Talassemia alfa/sangue , Talassemia alfa/patologia , Talassemia beta/sangue , Talassemia beta/patologiaRESUMO
As an alternative to the recently proposed screening for beta-thalassemias by isoelectric focusing (IEF) of denatured globin chains in urea-detergent gels [6], IEF of intact hemoglobins, obtained from umbilical cord blood in neonatal units, is reported here. For maximum separation, IEF should be performed in nonlinear pH gradients, in gels containing 0.2 M beta-alanine and 0.2 M 6-amino caproic acid, which flatten the pH gradient around pH 7, thus increasing the resolution between HbA and HbFac. The method can unambiguously detect homozygous and heterozygous beta-thalassemic conditions. A bimodal distribution of HbA at birth has been found: In heterozygous patients, HbA values of 9.02% (range 6.8-9.98%) have been found while in normal newborns HbA levels of 20.34% (range 11.02-30.6%) have been demonstrated.
Assuntos
Doenças do Recém-Nascido/diagnóstico , Focalização Isoelétrica , Talassemia/diagnóstico , Sangue Fetal/análise , Hemoglobina Fetal/análise , Hemoglobina Fetal/genética , Hemoglobina A/análise , Hemoglobina A/genética , Heterozigoto , Homozigoto , Humanos , Concentração de Íons de Hidrogênio , Lactente , Recém-Nascido , Doenças do Recém-Nascido/sangue , Doenças do Recém-Nascido/genética , Talassemia/sangue , Talassemia/genéticaRESUMO
A new isoelectric focusing technique for the separation and quantitation of glycosylated haemoglobin (HbA1c) is described. By using an equimolar mixture of two separators (0.2 M beta-alanine + 0.2 M 6-aminocaproic acid) a 2-pH unit Ampholine range (pH 6-8) is transformed in a shallow, 0.6-pH unit span (pH 6.7-7.3). This brings about an increment of resolution between HbA and HbA1c by a factor of about three, thus allowing proper densitometric evaluation of the trichloroacetic acid-fixed MetHb bands by conventional gel scanners. Excellent agreement is found among microchromatography, isoelectric focusing followed by densitometry in situ, and isoelectric focusing followed by band excision, elution and spectrophotometric determination. The present method also allows full resolution between HbA1c and fetal haemoglobins (F and Fac bands).