Abstract: Propionic acidemia is a common organic acid-metabolic disease in neonatal period. Because the clinical manifestations are lack of specificity, and the onset in neonatal period is often acute and critical, timely treatment is of a huge challenge. Two cases of propionic acid, twin brother and sister, from our department in June 2019 were reported, including our experience in diagnosis and treatment. The detailed medical history collection and routine laboratory examination can provide a strong guidance for early diagnosis and initial emergency treatment of the disease, and for the second-line laboratory examination to confirm the diagnosis. Blood tandem mass spectrometry and urine organic acid analysis can find the specific biochemical changes of various inherited metabolic diseases, including organic acid metabolism disorder, which play an important role in the early diagnosis. The definite diagnosis needs to test the activity of specific enzyme or the pathogenic genes. The next generation sequencing (NGS) is not only helpful for the definite diagnosis, but also helpful for the prenatal screening and the guidance of eugenics.

Key words: Brain diseases, metabolic, inborn；, Propionic acidemia；, Organicacids；, Case reports；, Twins, dizygotic