The plasma zinc/serum copper ratio as a biomarker in children with autism spectrum disorders

Abstract

The frequency of zinc deficiency, copper toxicity and low zinc/copper in children with autism spectrum disorders (ASDs) may indicate decrement in metallothionein system functioning. A retrospective review of plasma zinc, serum copper and zinc/copper was performed on data from 230 children with autistic disorder, pervasive developmental disorder-NOS and Asperger’s syndrome. The entire cohort’s mean zinc level was 77.2 μg dl⁻¹, mean copper level was 131.5 μg dl⁻¹, and mean Zn/Cu was 0.608, which was below the 0.7 cut-off of the lowest 2.5% of healthy children. The plasma zinc/serum copper ratio may be a biomarker of heavy metal, particularly mercury, toxicity in children with ASDs.

Keywords:

• Plasma zinc/serum copper ratio
• zinc deficiency
• metallothionein system dysfunction
• mercury
• autistic disorder
• pervasive developmental disorder-NOS
• Asperger’s syndrome

Acknowledgements

S.F. thanks the staff and administration of The Children’s Institute for their support during this project, including the help of several extraordinary students and volunteers including Carolyn Kobelak, CCC-SLP. The Heinz Endowments provided funding for the completion of this project. Additional acknowledgements go to Dr Skip Kingston’s research team at Duquesne University, including Timothy Fahrenholz and Dr Mizan Rahman. Most importantly, S.F. would like to thank his daughters for their patience and his wife, Marianne Faber, MOTR/L, for her understanding and her performance of ‘everything else’.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.