Disorders of vitamin B12 metabolism presenting through newborn screening

Area of Science:

• Biochemistry
• Newborn Screening
• Metabolic Disorders

Background:

• Elevated propionyl carnitine is the most frequent abnormality in newborn screening via tandem mass spectrometry.
• This finding occurs in 0.15% of newborns in South Australia.
• Vitamin B12 deficiency is the leading cause in this population, but inherited metabolic disorders are also considered.

Purpose of the Study:

• To outline an approach for confirmatory testing in infants with elevated propionyl carnitine.
• To present management strategies for these infants.
• To differentiate between vitamin B12 deficiency and inherited metabolic disorders.

Main Methods:

• Tandem mass spectrometry for initial newborn screening.
• Confirmatory biochemical testing for propionyl carnitine abnormalities.
• Diagnostic evaluation for inherited propionic and methylmalonic acid metabolism disorders and cobalamin deficiencies.

Main Results:

• Vitamin B12 deficiency is the most common etiology for elevated propionyl carnitine.
• Inherited disorders of propionic and methylmalonic acid metabolism and cobalamin deficiencies are important differential diagnoses.
• A structured approach to testing and management is crucial.

Conclusions:

• Prompt and accurate diagnosis is essential for infants with elevated propionyl carnitine.
• Management strategies should address both nutritional deficiencies and inherited metabolic conditions.
• Newborn screening programs play a vital role in early detection of these conditions.