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Objectives Determination of methylmalonic acid, 2-methylcitric acid, and total homocysteine in dried blood spots by liquid chromatography–tandem mass spectrometry has usually been used as a second-tier test to improve performance of newborn screening for propionylcarnitine-related disorders. However, factors that potentially affect its detection results have not been investigated, and we aimed to evaluate these influencing factors and explore their potential utility in newborn screening and initial follow-up for propionylcarnitine-related disorders. Methods This study comprised a prospective group (1998 healthy infants, to establish cutoff values and investigate the influencing factors) and a retrospective group (804 suspected positive cases screened from 381, 399 newborns for propionylcarnitine-related disorders by tandem mass spectrometry, to evaluate the performance of newborn screening and initial follow-up). Results Cutoff values for methylmalonic acid, 2-methylcitric acid, and total homocysteine were 2.12, 0.70, and 10.05 µmol/l, respectively. Concentration of methylmalonic acid, 2-methylcitric acid, and total homocysteine in dried blood spots is not impacted by sex, age, birth weight, gestational age, or dried blood spot storage time. A total of 75 of 804 cases were screened positive by combined tandem mass spectrometry and liquid chromatography–tandem mass spectrometry, thus eliminating 90% of the false positives without compromising sensitivity. Eighteen propionylcarnitine-related disorders were successfully identified, including one CblX case missed in the initial follow-up by tandem mass spectrometry. Conclusions Methylmalonic acid, 2-methylcitric acid, and total homocysteine detected in dried blood spots by liquid chromatography–tandem mass spectrometry is a reliable, specific, and sensitive approach for identifying propionylcarnitine-related disorders. We recommend this assay should be performed rather than tandem mass spectrometry in follow-up for propionylcarnitine-related disorders besides second-tier tests in newborn screening.

Aims Our study aimed to investigate changes in the prevalence of gestational diabetes mellitus (GDM) in the COVID‐19 pandemic and postpandemic era and the risk of adverse pregnancy outcomes in pregnant women diagnosed with GDM during the blockade period. Methods First, we investigated changes in the prevalence of GDM and the population undergoing oral glucose tolerance tests (OGTT) after the COVID‐19 pandemic. We then collected clinical information from pregnant women diagnosed with GDM to explore the risk of adverse pregnancy outcomes in pregnant women with GDM during the COVID‐19 pandemic. Results After the COVID‐19 pandemic, the proportion of pregnant women in the total number of outpatient OGTT tests decreased yearly. The ratio was 81.30%, 79.71%, and 75.48% from 2019 to 2021, respectively, with the highest proportion of pregnant women in February 2020 (92.03%). The prevalence of GDM was higher in March 2020 compared to the same period in 2019. However, from 2019 to 2021, the prevalence decreased year by year with 21.46%, 19.81%, and 18.48%, respectively. The risk of adverse pregnancy outcomes for pregnant women diagnosed with GDM during the most severe period of the COVID‐19 pandemic did not differ from before the COVID‐19 pandemic. Conclusions After the COVID‐19 pandemic, the prevalence of GDM increased during the most severe period of the epidemic, but the overall prevalence of GDM decreased year by year. In addition, the pandemic did not change the risk of adverse pregnancy outcomes in pregnant women with GDM.

Fatty acid oxidation disorders (FAODs) are a group of rare, autosomal recessive, metabolic disorders with clinical symptoms from mild types of fatigue, muscle weakness to severe types of hypoketotic hypoglycemia, (cardio)myopathy, arrhythmia, and rhabdomyolysis, especially during prolonged fasting, exercise, and illness. There are eleven diseases caused by thirteen FAOD genes (SLC22A5, ETFDH, ETFA, ETFB, SLC25A20, ACADS, ACADM, ACADVL, ACAT1, CPT1A, CPT2, HADHA, and HADHB) which are specific enzymes or transport proteins involved in the mitochondrial catabolism of fatty acids. We built the LOVD database for FAODs focused on the Chinese population, in which we recorded all the reported variants by literature peer review. In addition, the unpublished variant data of patients from Zhejiang province were also incorporated into the database. Currently, a total of 538 unique variants have been recorded. We also compared the incidence of high-frequency variants of certain FAOD genes among different populations. The database would provide the guidance for genetic screening of Chinese patients.