Screening blood spots for inborn errors of metabolism by electrospray tandem mass spectrometry with a microplate batch process and a computer algorithm for automated flagging of abnormal profiles

Abstract

Metabolic profiling of amino acids and acylcarnitines from blood spots by automated electrospray tandem mass spectrometry (ESI-MS/MS) is a powerful diagnostic tool for inborn errors of metabolism. New approaches to sample preparation and data interpretation have helped establish the methodology as a robust, high-throughput neonatal screening method. We introduce an efficient 96-well-microplate batch process for blood-spot sample preparation, with which we can obtain high-quality profiles from 500-1000 samples per day per instrument. A computer-assisted metabolic profiling algorithm automatically flags abnormal profiles. We selected diagnostic parameters for the algorithm by comparing profiles from patients with known metabolic disorders and those from normal newborns. Reference range and cutoff values for the diagnostic parameters were established by measuring either metabolite concentrations or peak ratios of certain metabolite pairs. Rigorous testing of the algorithm demonstrates its outstanding clinical sensitivity in flagging abnormal profiles and its high cumulative specificity.

Newborns with C8‐acylcarnitine level over the 90th centile have an increased frequency of the common MCAD 985A>G mutation

“…Newborn screening blotters from all newborns in the province of Nova Scotia are sent to the IWK Health Centre in Halifax, Nova Scotia, for metabolic screening for phenylketonuria, hypothyroidism and MCAD deficiency. The electrospray ionization tandem mass spectrometer (API 2000, MDS Sciex, Canada) analyses a 3 mm punch of each blood sample for phenylketonuria and MCAD deficiency using multiple reaction monitoring (MRM) and a method previously described (Rashed et al 1997). There were 831 newborn screening blotters that yielded C 8 -acylcarnitine results above the 90th centile (>0.088 mmol/L) for 12 consecutive months.…”

Genetics and genomic medicine in Saudi Arabia

“…The pioneering work of the Tandem Spectrometry Lab at KFSHRC on the use of electrospray in the implementation of tandem spectrometry in the analysis of various metabolites in body fluids is noteworthy. It has set the stage for the first implementation of computer-assisted algorithm in the simultaneous estimation of many metabolites and flagging of abnormal results, the basis of today's newborn screening around the world (Rashed et al 1994(Rashed et al , 1995(Rashed et al , 1997(Rashed et al , 1999. Owing to this history, KFSHRC has a long tradition in performing newborn screening for 16 different inborn errors of metabolism, which evolved into a pilot program starting in 2004 to screen newborns from participating hospitals around the country.…”

Newborn screening with tandem mass spectrometry: 12 months' experience in NSW Australia

“…Tandem mass spectrometry (MS/MS) with two mass spectrometers, on either side of a collision cell, offers an analytical technique capable of measuring many analytes with rapid throughput per sample (approximately 2 min) (1)(2)(3)(4)(5)(6). This technique also offers the advantage of simple sample preparation, as the first mass spectrometer is used to separate analytes within the sample, which are then altered in the collision cell and finally detected in the second mass spectrometer.…”