SUMA Technology and Newborn Screening Tests for Inherited Metabolic Diseases in Cuba: An Overview of the First 30 Years

Abstract The ultramicroanalytic system (SUMA), created in the 1980s, is a complete system of reagents and instrumentation to perform ultramicroassays combining the sensitivity of the micro-enzyme-linked immunosorbent assay (ELISA) tests with the use of ultramicrovolumes. This technology permitted establishing large-scale newborn screening programs (NSPs) for metabolic and endocrine disorders in Cuba. This article summarizes the main results of the implementation during the 30 years of SUMA technology in NSP for 5 inherited metabolic diseases, using ultramicroassays developed at the Department of Newborn Screening at the Immunoassay Center. Since 1986, SUMA technology has been used in the Cuban NSP for congenital hypothyroidism, initially studying thyroid hormone in cord serum samples. In 2000, a decentralized program for the detection of hyperphenylalaninemias using heel dried blood samples was initiated. These successful experiences permitted including protocols for screening congenital adrenal hyperplasia, galactosemia, and biotinidase deficiency in 2005. A program for the newborn screening of CH using the thyroid-stimulating hormone Neonatal ultramicro-ELISA was fully implemented in 2010. Nowadays, the NSP is supported by a network of 175 SUMA laboratories. After 30 years, more than 3.8 million Cuban newborns have been screened, and 1002 affected children have been detected. Moreover, SUMA technology has been presented in Latin America for over 2 decades and has contributed to screen around 17 million newborns. These results prove that developing countries can develop appropriate diagnostic technologies for making health care accessible to all.

Newborn screening for congenital adrenal hyperplasia in Cuba: six years of experience.

BACKGROUND: Since 2005, a newborn screening program for congenital adrenal hyperplasia (CAH) by measuring 17-alpha-hydroxyprogesterone (17OHP) in dried blood spots was introduced in Cuba. METHODS: The hormone was measured by the 17OHP Neonatal UMELISA method, in samples collected on the 5th day as average. Confirmatory test was performed to those neonates with 17OHP values above 55 nmol/l. Some perinatal factors that can influence on 17OHP levels were studied. RESULTS: From January 2005 to December 2010, 621,303 newborns were screened and 39 CAH cases were detected. Coverage of the program reached 98%. The incidence of CAH in Cuba was 1:15,931, similar to that reported by other programs. A recall for suspected CAH was performed in 10,799 cases (1.74%). Therapy in classical CAH patients was started at the mean age of 22 days. 17OHP levels were significantly higher in newborns with lower birth-weight (BW) and/or gestational age (GA). In addition, 17OHP values were affected by the gender, twin status or mode of delivery. CONCLUSIONS: In Cuba, the nationwide newborn screening program has allowed the early detection of CAH. The use of an optimized cut-off level for BW or GA could lead to a reduction in the percentage of recalled babies.

Quantitative ultramicrotest for newborn screening of galactosemia in Cuba.

BACKGROUND: To describe a simple, rapid, quantitative ultramicrotest (UMTEST) based on the fluorometric method introduced by Fujimura et al. adapted to an Ultra Micro Analytic System (SUMA) for the detection of total galactose (GAL) in dried blood specimens. METHODS: The assay uses 3 mm discs of dried blood on Whatman 903 filter paper and small volumes of each reagent. A methanol/acetone/water solution is used for deproteination, and a specially designed 96-well polystyrene opaque ultramicroplates, with a maximum capacity of 30 µL per well, are used for the reading. RESULTS: The UMTEST GAL is completed in 2 h, with measuring range of 0.28-3.92 mmol/L. The intra- and inter-assay coefficients of variation were 2.3%-8.9% and 6.8%-11.1%, respectively, depending on the total GAL concentrations. Percentage recovery ranged from 97.7% to 103%. Limit of detection and limit of quantitation were 0.06 and 0.16 mmol/L, respectively. The mean GAL concentration, in 2510 dried blood samples from the National Neonatal Screening Program was 0.23 mmol/L. Our assay showed high concordance correlations with the commercially available ICN Immuno-Chem™ GAL-MW EA kit. CONCLUSIONS: The analytical performance characteristics of this assay is suitable for mass newborn screening of galactosemia in Cuba.