Using the fluorescence spot test for neonatal screening of G6PD deficiency.

To establish the neonatal screening method of glucose-6 phosphate dehydrogenase (G6PD) deficiency, G6PD activity was measured using the fluorescence spot test (FST) using dried blood samples on filter paper. The G6PD/6PGD rate test of venous blood samples was further performed for confirmation. The positive G6PD deficiency rate was 4.2% and its detection rates were 3.7% for all neonates and 5.2% only for male newborns when FST was used for neonatal screening. Conformation rates by use of G6PD/ 6PGD ratio test for G6PD deficiency were 86.8% and 100% particularly in the severely deficient groups. Both sensitivity and specificity were very high in the severely deficient groups. FST can be used in neonatal screening of G6PD deficiency because of its high accuracy, applicability, and simplicity. Moreover, a high volume of dried blood samples on filter paper can be tested quickly. It is very favorable to diagnose and treat G6PD deficiency early in high incidence districts.

Neonatal screening and monitoring system in Taiwan.

Neonatal screening in Taiwan started as a pilot program in 1981. The coverage rate increased to 90% in 1990, and is currently more than 99%. Five diseases are covered in the screening program including congenital hypothyroidism, phenylketonuria, homocystinuria, galactosemia, and glucose-6-phosphate dehydrogenase deficiency. A monitoring system was established at the same time to ensure correct diagnosis and treatment for positive cases. Neonatal screening is not compulsory by law in Taiwan, but the government is very concerned about it. New tests for neonatal screening have recently been included as pilot programs. Parents of the newborns have to pay for these tests, for which informed consent has to be given. These additional tests include screening for congenital adrenal hyperplasia and tandem mass screening. The results of these pilot programs will be offered to the government for policy decision-making in the future.

Quality assurance program for neonatal screening of glucose-6-phosphate dehydrogenase deficiency.

The nationwide neonatal screening of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Taiwan was started on July 1, 1987. The effective collection rate has reached more than 96% of all newborns since 1993 and the overall incidence rate of G6PD deficiency was about 2%. This screening program has 3 screening centers and 18 referral hospitals, distributed around Taiwan including outlying islands. To assess the reliability of the confirmatory and screening tests, an external quality assurance (QA) program for G6PD assay was developed. For quantitative assay of G6PD activity, lyophilized quality control materials with different G6PD activities were prepared from red blood cells. For G6PD screening, quality control materials with different G6PD activities were prepared from whole blood and spotted onto the blood collecting filter paper. Periodically (1-2 months), the QC materials were sent to each of the referral hospitals and screening centers by speed post delivery. The external QA results were evaluated and compared to the median of all the reports and the reference values determined by our laboratory. Whenever an analytical system error was detected in any participating laboratory, troubleshooting was carried out either by contacting by phone or visiting in person. Twenty-one referral laboratories and 8 screening centers (3 in Taiwan, 2 in Mainland China, and one each in the Philippines, Thailand and Lebanon) participated in the QA program. Three to 5 QC specimens were sent to every participating referral laboratory for each quantitative survey. From January 1988 to June 2001, 104 QA surveys were carried out and 1,891 reports were received. Two hundred and thirty-nine (12.6%, 239/1,891) QA reports had abnormal results, attributed to clerical (13%, 31/239), experimental (17.2%, 41/239), and instrumental errors (46.4%, 111/239). Most of the experimental and instrumental errors were found in those laboratories that did not execute internal QA properly. For the screening QA program, 10 QC blood spots were delivered to every participating screening center for each survey. From March 1999 to June 2001, 15 screening surveys were performed with 111 reports received. One false negative (1/1,110) and 14 (14/1,110) false positive results were found in four (3.6%, 4/111) of the screening QA reports. The external quality assurance program proved useful for monitoring the performance of G6PD tests in referral hospitals and screening centers, and provided guidance for correcting analytical errors.