Raquel Weber

Prevalence of G6PD deficiency in newborns in the south of Brazil

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked disorder which causes neonatal jaundice in most cases, and in association with intake of drugs or certain foods (for example fava) can cause haemolytic crises. The aim of this study was to determine the prevalence of G6PD deficiency in Rio Grande do Sul (RS), the southernmost state of Brazil. We tested 2799 newborn blood samples. A commercial kit was used for the quantitative measurement of G6PD activity. Of the 2799 samples, 39 (1.4%) exhibited total deficiency, 178 (6.4%) exhibited intermediate deficiency and 2582 (92.2%) were normal. We found no correlation between G6PD deficiency and ethnic origin, but a high prevalence of patients with partial deficiency could be associated with the type of colonization of RS. The combined prevalence for both types of deficiency (complete and partial) was 7.9% among the newborn population. This finding is important as both types of deficiency must receive same kind of preventive care.

Molecular characterization of glucose-6-phosphate dehydrogenase deficiency in patients from the southern Brazilian city of Porto Alegre, RS

Glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) deficiency is one of the most common human enzymopathies throughout the world. Although most affected individuals are asymptomatic, there is a risk of neonatal jaundice and acute hemolytic anemia which can be triggered by infection, some pharmaceuticals and, in older individuals, eating fava beans. We characterized the molecular basis of G6PDH deficiency in a sample of 348 adults from Porto Alegre (population about 1.5 million), the capital of the southernmost Brazilian state of Rio Grande do Sul. Genomic DNA was extracted from peripheral blood leukocytes. We studied the three G6PDH mutations that appear to be the most frequent in Southern Brazil, the G202A and A376G A minus (A-) variants and the C563T Mediterranean (Med) variant. From July 2004 to October 2005, 348 patients (162 Females plus 186 males, age range 0 to 82 years) from Porto Alegre were referred to our laboratory for G6PDH analysis, 36 (9.7%) of which showed deficient G6PDH activity. These 36 patients and 34 randomly-selected non-deficient control individuals were submitted to molecular analysis which revealed a predominance of G6PDH A- allele among the deficient patients. The prevalence of the G6PDH A- variant agrees with its distribution among the ethnic groups that colonized RS, especially those of African, Portuguese, Spanish, and Italian origin.

Determinação da acurácia do método qualitativo da medida da atividade da glicose-6-fosfato desidrogenase

Glucose-6-phosphate dehydrogenase deficiency (G6PD) is a public health problem which affects about 400 millions of people all over the world. Some methods that measure the activity of G6PD have already been developed. Thus, the aim of this study was to evaluate the accuracy of the Brewers method compared with a standard reference and estimate the prevalence of G6PD deficiency in the sample. A cross-sectional study of a group of patients in HCPA presenting with jaundice was carried out from June 2004 to May 2005. Samples were processed by the metahaemoglobin reduction test (Brewers method) and by the method of Haemoglobin Normalization, which was used as the standard reference. A total of 173 patients were analyzed for G6PD activity. The ages varied from one day to 82 years old with 66% of the sample being less than 16 days old. The mean activity and standard deviation of G6PD for the analyzed sample was 17.67 ± 5.66 U/gHb. The estimated frequencies of G6PD deficiency for the standard reference and Brewers method were 13 (7.7%) subjects (total or partial deficiency) and 14 (8.67%), respectively. When the Brewers method was compared with the quantitative method of Hemoglobin Normalization, it showed a sensitivity of 92.8% and specificity of 98.7%. As G6PD deficiency predominates in our society, low cost tests, such as the Brewers test can be used for screening this deficiency, mainly to monitor newborn babies who are at risk of developing jaundice.

An evaluation of IRT neonatal analytical performance in AutoDELFIA

Neonatal screening programs for cystic fibrosis (CF) usually consist of an immunoreactive trypsinogen assay. The objective of this study was to validate the AutoDELFIA® Neonatal immunoreactive trypsinogen kit. We carried out a comparative study between two equipments. The following results were yielded: random error = 26.6%, systematic error = 4.95% and analytical error = 31.5%. Several factors contributed to the assay variations in dried blood spot, namely chromatographic, hematocrit and total blood volume effects. These factors should be taken into account in the assessment of validation results. The studied kit can be deployed in neonatal screening routine.

Evaluation of the Genetic Screening Processor for the Performance of Newborn Screening Tests

The collection of dried blood spots (DBSs) on filter paper has been a powerful tool in newborn screening (NBS) programs and in other fields. However, filter paper has been associated with some leve...