No abstract

The present work describes the value of genetic analysis as a confirmatory measure following the detection of suspected inborn errors of metabolism in the Spanish newborn mass spectrometry screening program. One hundred and forty-one consecutive DNA samples were analyzed by next-generation sequencing using a customized exome sequencing panel. When required, the Illumina extended clinical exome panel was used, as was Sanger sequencing or transcriptional profiling. Biochemical tests were used to confirm the results of the genetic analysis. Using the customized panel, the metabolic disease suspected in 83 newborns (59%) was confirmed. In three further cases, two monoallelic variants were detected for two genes involved in the same biochemical pathway. In the remainder, either a single variant or no variant was identified. Given the persistent absence of biochemical alterations, carrier status was assigned in 39 cases. False positives were recorded for 11. In five cases in which the biochemical pattern was persistently altered, further genetic analysis allowed the detection of two variants affecting the function of BCAT2, ACSF3, and DNAJC12, as well as a second, deep intronic variant in ETFDH or PTS. The present results suggest that genetic analysis using extended next-generation sequencing panels can be used as a confirmatory test for suspected inborn errors of metabolism detected in newborn screening programs. Biochemical tests can be very helpful when a diagnosis is unclear. In summary, simultaneous genomic and metabolomic analyses can increase the number of inborn errors of metabolism that can be confirmed following suggestive newborn screening results.

Our results support the new ESPGHAN 2012 guidelines for diagnosis of CD can be safely used without the risk of overdiagnosis. A prospective multicentre study is needed to confirm our results.

Here we report a 7-month-old girl with long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) deficiency with hypoketotic hypoglycemia; the mother had a history of acute fatty liver in a previous pregnancy leading to fetal death at 34 weeks of gestation. The misense mutation 1528G > C was detected in both alleles in the proband and in one allele in both parents. We emphasize that screening for fatty acid oxidation disorders and specifically LCHAD deficiency should be performed in newborns from mothers with hepatic complications during pregnancy such as acute fatty liver of pregnancy or severe or recurrent HELLP syndrome.