Incidence and patterns of inborn errors of metabolism in the Eastern Province of Saudi Arabia, 1983-2008

<b>Background and Objectives</b> :Individual inborn errors of metabolism (IEM) are rare disorders, but may not be that uncommon in our patient population. We report the incidence of IEM in a defined cohort of births at the Saudi Aramco medical facilities in the Eastern Province of Saudi Arabia over 25 years. <b> Methods</b> : The records of all patients diagnosed with IEM from 1 January 1983 to 31 December 2008 were reviewed and categorized according to accumulated or deficient metabolites into small-molecule disorders (aminoacidemia, organic acidopathies [OA], urea cycle defects, fatty acid oxidation, and carbohydrate metabolic disorders) and other disorders, including glycogen and lysosomal storage disorders (LSDs), and organelle disorders. <b> Results</b> : During the study period, 165 530 Saudi Arabian infants were born at Saudi Aramco and 248 were diagnosed with an IEM, corresponding to a cumulative incidence of 150 cases per 100 000 live births. Small-molecule disorders were diagnosed in 134/248 patients (54&#x0025;). OA were the most common (48/248 patients; 19&#x0025;), and methylmalonic aciduria was the most frequently observed OA (13/48 patients; 27&#x0025;). LSDs were diagnosed in 74/248 patients (30&#x0025;), and mucopolysaccharidosis was the most frequently observed LSD (28/74; 38&#x0025;). <b>Conclusion</b> : We believe that our data underestimate the true incidence of IEM in the region. Regional and national newborn screening programs will provide a better estimation of the incidence of IEM. We recommend a centralized newborn screening program that employs tandem mass spectrometry