A retrospective ESI-MS/MS analysis of newborn blood spots from 18 symptomatic patients with organic acid and fatty acid oxidation disorders diagnosed either in infancy or in childhood.

To assess the usefulness of newborn mass screening by ESI-MS/MS in Japan, an acylcarnitine analysis of blood spots on filter paper from collected from newborn infants at the age of 5 days was retrospectively conducted on 18 cases of inherited metabolic diseases that had already been diagnosed. The patients had organic acid disorders in 8 cases, fatty acid oxidation disorders in 7 cases, and amino acid disorders in 3 cases. The time of onset was from 0 days to 1 year 8 months of age. In 16 out of the 18 cases studied, it was confirmed that the analysis of the blood spots on filter paper collected during the newborn period could detect disorders. One case each of CPT-2 deficiency and citrin deficiency could not be detected in the newborn period. Regarding CPT-2 deficiency, the establishment of sufficient nutrition might have interfered with the detection of the disorder because the blood was collected at 5 days of age. The disorders occurred within 1 week after birth in 4 out of 18 cases, 2 of which died at an early stage. Among 13 cases in which the disorders occurred after 1 month, 10 cases were caused by defective metabolism due to infections. The prognoses of inherited metabolic diseases that occur in the early newborn period are limited. However, this study suggests that prognoses of metabolic disorders that occur after the newborn period can expect to be improved by early detection.