A False-Positive Case of Methylmalonic Aciduria by Tandem Mass Spectrometry Newborn Screening Dependent on Maternal Malnutrition in Pregnancy.
Int J Environ Res Public Health
; 17(10)2020 05 20.
Article
em En
| MEDLINE
| ID: mdl-32443888
ABSTRACT
Methylmalonic Acidurias (MMAs) are a group of inborn errors of metabolism (IEMs), specifically of propionate catabolism characterized by gastrointestinal and neurometabolic manifestations resulting from a deficiency in the function of methylmalonyl-CoA mutase, methylmalonyl-CoA epimerase, and cobalamin metabolism. In Expanded Newborn Screening (NBS), increased levels of propionylcarnitine (C3) and/or of its ratios by MS/MS analysis of dried blood spots (DBS) samples are suggestive for either Propionic Acidemia or MMAs. C3 elevation is not considered a specific marker for these disorders, resulting in high false-positive rates. The use of analyte ratios improves specificity, but it still cannot resolve the diagnostic issue. Second-tier testing are strongly recommended as confirmation of primary NBS results and for a differential diagnosis. LC-MS/MS analysis allows the quantification of more specific markers of the disorder. Here, we report the case of a newborn with a suspected MMA at Expanded NBS and at second-tier test. Given the urgent situation, in-depth diagnostic investigations were performed. Further investigations surprisingly revealed a Vitamin B12 deficiency due to a maternal malnutrition during pregnancy. This case emphasized that metabolic alterations at NBS may not only be influenced by genome and related to IEMs, but also to external factors and to maternal conditions.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Deficiência de Vitamina B 12
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Exposição Materna
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Desnutrição
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Espectrometria de Massas em Tandem
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Erros Inatos do Metabolismo dos Aminoácidos
Tipo de estudo:
Diagnostic_studies
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Screening_studies
Limite:
Female
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Humans
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Newborn
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Pregnancy
Idioma:
En
Revista:
Int J Environ Res Public Health
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Itália