Short-term stability of amino acids and acylcarnitines in the dried blood spots used to screen newborns for metabolic disorders.

OBJECTIVE: Tandem mass spectrometry is increasingly used in the Middle East in newborn screening for inborn errors of metabolism using dried blood spots. The sensitivity and specificity of this system for analyzing fatty and amino acids, screening for more than 40 metabolic conditions, is known. However, the short term stability of acylcarnitines and amino acids in dried blood spots in extreme heat and humid conditions is not well documented. We examined the short term effect of heat and humidity on the levels of 7 amino acids and 10 acylcarnitines used in newborn screening for inherited metabolic disorders. METHODS: Dried blood spots were exposed with humidity <30% to temperatures of 4, room temperature, 37° C, and 45, and also with humidity >70% at 37° C and 45. Amino acids and acylcarnitines in the dried blood spots were analyzed by tandem mass spectrometry. RESULTS: During the eight days of the study in high temperature and high humidity storage, most acylcarnitines and amino acids lost almost 50% of initial concentration. After eight days' exposure at 37 and 45 with humidity >70%, methionine was determined to be the most sensitive, and phenylalanine and leucine were the least sensitive amino acids. At 37 with humidity >70% C6 was the most sensitive and free carnitine (C0) was the least sensitive acylcarnitine; at 45 with humidity >70% C16 was the most sensitive and C0 was the least sensitive. CONCLUSION: Low humidity and low temperature conditions are required for transportation and storage of dried blood spots.

Selective newborn screening of inborn errors of amino acids, organic acids and fatty acids metabolism in the Kingdom of Bahrain.

Mandatory newborn screening for metabolic disorders has not been implemented in most Middle Eastern countries. Early detection and treatment of inborn errors of metabolism can reduce mortality and minimize morbidity. Preliminary studies conducted in some parts of Middle East suggest that the incidences of inborn errors of metabolism are reported to be higher in the region than anywhere else in the world due to the consanguinity. In this study the incidence of inborn errors of amino acids, organic acids and fatty acids oxidation disorders was investigated from the results of blood spot analysis of 1986 symptomatic children from 1st January 2008 to 31st of December 2011. Out of 1986 newborns screened 25 infants were diagnosed and confirmed with amino acids (n=11), organic acids (n=9) and fatty acids oxidation (n=5) disorders. Overall incidences based on number of live birth between 2008 and 2011 inclusive were 1:6000, 1:8000 and 1:14,000 for amino acids, organic acids and fatty acids oxidation disorders; respectively. Out of 25 infants diagnosed, 21 were the children of first cousin marriages. Results from this study suggest high incidence of inborn errors of amino acids, organic acids and fatty acids oxidation metabolism in Bahrain and significant contribution of consanguinity in inherited metabolic disorders. Mandatory screening for inborn errors of metabolism in Bahrain is highly recommended.