Screening newborns for multiple organic acidurias in dried filter paper urine samples: method development

Area of Science:

• Biochemistry
• Metabolomics
• Neonatal Screening

Background:

• Inherited and acquired organic acidurias in newborns can lead to severe disease, intellectual disability, and death.
• Early detection through newborn screening is crucial for preventing adverse outcomes.
• Existing screening methods may not cover the full spectrum of organic acidurias.

Purpose of the Study:

• To develop and validate a novel screening method for detecting a wide range of organic acidurias in newborns using dried urine filter paper samples.
• To identify key organic acid markers for at least 20 different metabolic conditions.

Main Methods:

• A sensitive and specific method using automated computerized gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring was developed.
• Eight key organic acid markers were quantified: methylmalonic acid, 2-hydroxyisocaproic acid, glutaric acid, propionylglycine, isovalerylglycine, 3-methylcrotonylglycine, hexanoylglycine, and 3-phenylpropionylglycine.
• Urine extracts were prepared similarly to neuroblastoma screening, and extraction efficiencies and marker stability on filter paper were assessed.

Main Results:

• The method successfully screened for markers of over 20 metabolic conditions, including various acidurias and vitamin deficiencies.
• Extraction efficiencies ranged from 40-80% for most markers, with propionylglycine at 11-13%.
• Marker stability on filter paper was adequate for 15 days, and normal levels were established in 519 newborn samples.

Conclusions:

• The developed method is effective for screening dried urine filter paper samples for multiple organic acidurias in newborns.
• This screening approach holds significant potential for early diagnosis and prevention of severe consequences associated with these metabolic disorders.
• The method's reliability and applicability were demonstrated through testing on patient samples.