An infant presenting clinically with CPTII deficiency which was missed by standard newborn screening.

microscope

Presented By:

1,2Anita, Inwood, BaRN, GradDip, MNP, anita.inwood@health.qld.gov.au, +61415674527
1Michelle Lipke, MBBS, FRACP, HGSA (clinical Geneticist),
1Kalli Demetriou, MBBS
1Talhee Minto, MBBS
3Gabriel Crisp, BaSc
1,2David Coman, MBBS, MPHIL, FRACP, HGSA (clinical Geneticist)
4Dianna Ting, MBBS, FRACP
1,3Jim McGill, MBBS(hons), FRACP, HGSA (clinical Geneticist), FRCPA (biochemical Genetics)

1Queensland Lifespan Metabolic Medicine Service, South Brisbane, Queensland, Australia
2University of Queensland, St Lucia, Queensland, Australia
3 Pathology Queensland, Herston, Queensland, Australia
4 Peas in a Pod, Woolloongabba, Queensland, Australia

The Queensland Newborn Screening Programme tests approximately 65,000 births per year. This abstract presents a male infant, presenting in the first day of life with symptomatic hypoglycaemia (glucose 1.1 mmol/L). The baby did not pass urine for 8 hours after the event consistent with poor breast milk intake.

An acylcarnitine collected as part of the hypoglycaemia screen was diagnostic of carnitine palmitoyl transferase type II (CPTII) or carnitine-acylcarnitine translocase deficiency (CACT)-: Palmitylcarnitine (C16): 4.1umol/L (<0.74), Oleoylcarnitine (C18:1): 2.78umol/L (<0.27); acetylcarnitine (C2): 14umol/L (1- 13) and (C16+C18:1)/C2 ratio 0.59 (<0.1). The infant was treated with intravenous 10% dextrose therapy. He was well but still on intravenous dextrose in addition to breast feeds at time of collection of the newborn screening sample, at fifty-two hours of age, which was normal. Currently our newborn screening program only recommends notification of the absence of lactose containing feeds for infants on intravenous glucose.

Repeat acylcarnitine profile on day five when on oral feeds showed C16: 0.8 umol/L, C18:1: 0.73umol/L(<0.27) and (C16+C18:1)/C2 was 0.26 (<0.1). DNA testing showed two pathogenic variants, c.1511C>T (p.Pro504Leu) and c.338C>T (p.Ser113Leu). in the CPT2 gene.

Conclusion: This case shows that parenteral glucose can impact on newborn screening results and increase the chance of missing some infants affected with a fatty acid oxidation disorder. We suspect that the mild or later onset fatty acid oxidation disorders are most at risk of being missed and these may also be missed if newborn screening was repeated several days later.

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