Novel Test to Ensure Essential Treatment for Newborns with Serious Genetic Disease

HCU affects an infant's ability to metabolize the amino acid methionine, which is an essential protein component found in breast milk. This leads to an abnormal increase in levels of methionine and another amino acid known as homocysteine, which, in turn, could cause complications ranging from skeletal and eye problems to intellectual disabilities and vascular abnormalities. Early detection and treatment of HCU can prevent these complications. However, current tests only gauge methionine levels, which remain low during newborn screening. Thus, around 50% of HCU cases remain unidentified, leaving them at high risk of going untreated.

Scientists at the Centers for Disease Control and Prevention (CDC, Atlanta, GA, USA) have developed a new test that could markedly enhance the quality of life for infants with HCU and also demonstrated its efficacy. In newborns with HCU, homocysteine levels exhibit an early, significant rise - generally before methionine levels - which makes it an ideal marker for detecting the disease during the first few days of life when screening is performed. This makes homocysteine a better early marker of HCU in infants.

The research team evaluated the performance of the test by using it to screen residual newborn screening specimens procured from infants who had already received HCU diagnoses. The specimens included 100 samples from healthy infants, 50 samples from HCU-negative infants receiving total parenteral nutrition (TPN) in the NICU, and two samples from HCU-positive infants. Impressively, the test effectively distinguished between healthy and HCU-positive samples. Additionally, the specimens procured from infants receiving TPN treatment were accurately classified as HCU-negative, which is crucial because traditional methionine tests for HCU tend to produce a high number of false positives in babies receiving TPN.

“Here we present the only flow injection analysis–tandem mass spectrometry first-tier newborn screening method that directly quantifies total homocysteine from dried blood spots,” said Konstantinos Petritis, Ph.D., at the CDC who led the group of researchers. “The ability to screen total homocysteine during first-tier newborn screening is a significant step toward reducing HCU false-negative rates, which will enable early identification and intervention to reduce HCU-associated morbidity and mortality.”

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