Detection of glutaric acidemia type 1 in infants through tandem mass spectrometry

Abstract

Glutaric acidemia type 1 (GA1) is a rare inherited metabolic disorder which goes underdiagnosed due to its latency period and subtle presentation. A pilot clinical study was conducted to assess the usefulness, specificity and sensitivity of the tandem mass (MS/MS) spectrometer, specifically the Abbott (AB) Sciex 3200, in the screening for GA1 using dried blood spots. A total of 17,100 specimens, comprising pediatric patients and healthy newborns, were screened from June 2012 to June 2014. A selection criterion was applied to increase the range of samples tested. 14 of the total specimens tested presumptive positive for GA1, of whom all were symptomatic. The diagnosis was confirmed in 4 of the 14 cases and they were started on treatment. 4 cases expired before confirmation. The remaining cases were empirically started on treatment. Most of the patients responded favorably to the dietary management. One important observation was that the older symptomatic children diagnosed with GA1 had poorer outcomes in terms of recovery of delayed milestones and mental deterioration, further emphasizing the need for early diagnosis of organic acidemias along with the other biochemical defects. Tandem mass spectrometry was found to be more than 93.33% sensitive and more than 99.42% specific. The screening test proved to be very simple and economical.

Keywords

• Glutaric acidemia
• Tandem mass
• Organic acidemias