GC/MS as a One-Step Metabolomics Analysis for Symptomatic Screening of Inherited Metabolic Disorders: A Regional Experience in Northern Spain

BACKGROUND: New-born screening (NBS) using MS/MS technology started in northern Spain region with a restricted disease panel for four Inborn Errors of Metabolism (IEM) (phenylketonuria [PKU], glutaric aciduria type-1 [GA-1], medium-chain acyl-CoA dehydrogenase [MCAD] and long-chain 3-hydroxyacyl-CoA dehydrogenase [LCHAD] deficiencies) within the last years. We report the results of the two strategies for a three-year period in a developed region of northern-Spain and present the incidence and clinical presentation features of IEM in our Hospital. METHODS: From January 2015 to December 2017 dried blood spots (DBSs) specimens from 12, 915 new-borns were included in the regional NBS program. In the same period, 134 urine samples collected from patients who were highly suspected of having IEM or with a positive result in the NBS, were evaluated using GC/MS. RESULTS: During the period, just one patient (PKU) was diagnosed by the NBS program, and other seven studies were positives, being negatives in the second-tier GC/MS-urine analysis. By GC/MS-urine analysis of highly suspected IEM, eight cases of IEMs were diagnosed, plus three other patients with secondary, but symptomatic, methylmalonic aciduria (MMA) due to maternal B12 deficiency. Symptoms were neurological in 7 of 11 (63 %) patients, followed by failure to thrive in 6 of 11 (54 %) patients and vomiting in 5 of 11 (45 %) patients. CONCLUSIONS: The present study highlights the feasibility of using GC/MS as a one-step analysis for symptomatic metabolic screening, which is particularly useful for regional hospitals. The incidence of treatable IEM is at least 1 in 1, 435 new-borns, or 1 in 1, 076 new-borns considering secondary MMA.