Selective screening for inborn errors of metabolism by tandem mass spectrometry in Egyptian children: a 5 year report.

Objective: In order to enhance awareness and promote registry for inborn errors of metabolism (IEMs) in Egypt, we aimed to evaluate the prevalence and main clinical findings of IEMs detectable by tandem mass spectrometry (MS/MS) among high risk pediatric patients presenting to our tertiary care facility at Cairo University Children's Hospital over a period of 5 years and to compare the disease burden in Egypt in the absence of a national screening program for inherited metabolic disorders with other populations.

Methods: During this period 3380 Egyptian children were suspected of having IEMs based on clinical/laboratory presentation and were analyzed by MS/MS. Confirmatory testing was performed according to flagged analyte by MS/MS using a different sample type such as plasma or urine or by a different technique such as GC/MS.

Results: A relatively high number of patients (203/3380 (6%)) were confirmed with 17 different types of IEMs. Averages for age at diagnosis for different disorders ranged from 2.5 months to 6.6 years with general developmental delay and irreversible neurological damage being the most common presenting features (75.9% and 65.5%, respectively). Amino acid disorders (127/203 (62.6%)), mainly phenylketonuria (100/203 (49.3%)), were the most encountered, followed by organic acidemias (69/203 (34%)), while fatty acid oxidation defects (7/203 (3.4%)) were relatively rare. 88% of patients were born to consanguineous parents.

Conclusions: The development of a nationwide screening program for IEMs is mandatory for early detection of these potentially treatable disorders, prompt and properly timed therapeutic intervention and prevention of the devastating neurological outcomes.