Clinical Application of Liquid Chromatography Tandem Mass Spectrometry Using Dried Blood Spot as a More Rapid Method for Determination of Methylmalonic Acid, Propionylcarnitine, and Total Homocysteine

Abstract Methylmalonic acidemia (MMA) should be diagnosed in early infancy and receive appropriate management promptly after the diagnosis to prevent severe complications leading to death. At present, a newborn screening (NBS) method using tandem mass spectrometry (MS/MS) identifies suspected patients with MMA by elevated propionylcarnitine. In addition, a liquid chromatography tandem mass spectrometry (LC/MS/MS) method using dried blood spot is effective to detect some metabolites as a second-tier test, and reduces the false-positive rate in NBS. However, these tests were only used in screening, and not applied as an examination for evaluating treatment. Herein, we describe a 57-day-old girl with MMA under treatment with cobalamin who had elevated urinary methylmalonic acid levels. We applied the LC/MS/MS method with a separation column to evaluate her cobalamin responsiveness, and discovered an insufficient cobalamin dose earlier than would have been possible using other methods. Based on the current data, this method seems to be applicable for the follow-up of the treatment of MMA patients. However, this should be confirmed with more experience with a larger number of cases and a wider spectrum of disorders.

Quality of Life and Associated Factors in Japanese Children With Inborn Errors of Metabolism and Their Families

Abstract To reveal the associated factors of quality of life (QoL) in children with inborn errors of metabolism (IEM), their siblings, and their primary caregivers and partners, we conducted an anonymous questionnaire survey in Japan. Descriptive, correlation, and multiple regression analyses were performed. Fifty-six children with IEM, 35 siblings, 143 primary caregivers, and 86 partners completed our questionnaires. There were significant positive correlations between higher QoL in children with IEM and lower disease influence (r »0.46) and higher perceived emotional support (r »0.67). We could not find any associated factor of siblings' QoL. Lower parental distress, higher family empowerment, and higher household income contributed to higher QoL in primary caregivers (adjusted R2 » 0.636). Higher household income, lower anxiety about childrearing, and higher satisfaction in the relationship with the child and entire family contributed to higher QoL of partners (adjusted R2 » 0.398). We concluded that developing effective interventions to improve QoL is needed for the entire family in future outpatient settings.