cPMP rescue of a neonate with severe molybdenum cofactor deficiency after serendipitous early diagnosis, and characterisation of a novel MOCS1 variant.

We report the first, and so far, only index patient with neonatal onset MoCD type A who was diagnosed and treated early enough with cPMP to avoid severe brain injury and disability. The child presented with hypoglycemia at the age of 10 h and was diagnosed because of the incidental finding of severely decreased L-cystine in plasma. Due to a high level of awareness and excellent co-operation between metabolic laboratory and clinical services, cPMP substitution could be initiated before severe encephalopathy set in, and the child subsequently had a normal motor development.

Retrospective Review of Positive Newborn Screening Results for Isovaleric Acidemia and Development of a Strategy to Improve the Efficacy of Newborn Screening in the UK.

Since the UK commenced newborn screening for isovaleric acidemia in 2015, changes in prescribing have increased the incidence of false positive (FP) results due to pivaloylcarnitine. A review of screening results between 2015 and 2022 identified 24 true positive (TP) and 84 FP cases, with pivalate interference confirmed in 76/84. Initial C5 carnitine (C5C) did not discriminate between FP and TP with median (range) C5C of 2.