Preliminary results of Egypt’s experience for use of tandem mass spectrometry for expanded metabolic screening

الملخص EN

Background : It is suspected that metabolic disorder rates among Egyptian newborn has high incidence due to the prevalence of consanguinity (38 %), where NBSfor metabolic disorders is neither mandatory nor available.

Aims : This pilot study is the first attempt to elicit prevalence of metabolic disorders in Egypt by tandem mass spectrometry (MS / MS).

Methods : 16000 neonates (3-7 days) and 550 children (3 months to 15 years) presenting to the neuro metabolic outpatient (OP) clinic at Cairo University Children Hospitals (CUCH) underwent expanded metabolic screening by MS/MS .

Dried blood spots samples-were extracted with methanol containing Deuterated internal standards, derivatized by an in-house method for sample preparation and submitted to MS/MS analysis.

Amino acids& acylcarnitine values were calculated through built-in program.

Method validation was achieved through participation in CDC NBSQA program and our own QC samples.

Results : From the 16000 screened neonates, 10 cases were detected (l / 1600).They were 4 PKU (1 / 4000), lease MSUD (1 / 16000), 5 cases with abnormal acylcarnitine profile approximately (1/3000).

Accordingly, the first Egyptian reference values for expanded screening by MS/MS were calculated.

From 550 patients presenting to the neurometabolic clinic, 24 patients with metabolic disorders were detected approximately (1 / 23).

They were 14 PKU cases (1 / 39), 2 MSUD (1 / 275), 1 patients with citullinemia(l / 550) , 2 homocystinuria (1 / 275) and 5 cases with abnormal acylcarnitine profile (1 / 110) Conclusion : MS/MS technology was effective in identifying several metabolic disorders.

Overall incidence was found to be high particularly among disabled children, who could have been saved from disabilities if expanded NBS was offered.

The study provided the first Egyptian reference values for amino acids and acylcarnitines measured by MS / MS for newborns.