There is now a growing body of scientific research, which has found that disturbances in copper and zinc metabolism to play a role in the etiology of Autism Spectrum Disorders.
Autism spectrum disorders (ASDs) are a group of developmental disabilities that can cause significant social, communication and behavioral challenges.
Copper is an essential trace element required in small quantities, however under certain conditions copper can elevate to toxic levels. This situation is exacerbated by zinc deficiency and low levels of zinc.
A number of studies have now found elevated copper levels and sometimes low zinc, in individuals with autism spectrum disorders.
I believe the inconsistency with the zinc levels between studies, is because of the differences in testing being used. Red blood cell testing would probably be a more reliable indicator of true zinc status.
Elevated Copper & Low Zinc Levels In Autism Spectrum Disorders
A fairly recent study from 2014 found lower serum zinc levels, zinc/copper ratio was significantly lower and serum copper levels were substantially higher in Chinese children with Autism Spectrum Disorders, than normal controls.
The results indicated that the mean serum Zn levels and Zn/Cu ratio were significantly lower in children with ASD compared with normal cases (P<0.001, respectively), whereas serum Cu levels were significantly higher (P<0.001).
The study concluded that the results suggested an association between serum levels of Zn and Cu and Autism Spectrum Disorders among Chinese patients, and the Zn/Cu ratio could be considered a biomarker of ASD. 
A study published in 2011 assessing copper and zinc levels in individuals with Asperger’s Syndrome, Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) and Autism found that:
Autistic and PDD-NOS individuals had significantly elevated plasma levels of copper. None of the groups (autism, Asperger’s or PDD-NOS) had significantly lower plasma zinc concentrations. 
Another study from 2011 published in the Journal of Nutrition & Metabolic insights found:
Autistic individuals had significantly elevated plasma levels of copper and Cu/Zn and lower, but not significantly lower, plasma Zn compared to neurotypical controls.
These results suggest an association between zinc and copper plasma levels and autism, and they suggest that zinc therapy may be most effective at lowering copper levels in autistic children with GI disease. 
Heavy Metal Toxicity, Mercury Overload & Autism
An interesting finding from one of the studies was an explanation on the possible mechanism of how mercury and other toxic metals accumulate, in individuals with ASD’s and how it relates to copper/zinc levels.
The study found that zinc deficiency causes metallothionein (MT) dysfunction, which as the literature suggests may allow mercury to accumulate as a consequence.
The literature suggests that mercury accumulation
may occur as a cause or consequence of metallothionein (MT) dysfunction in children diagnosed with an ASD, which may be one of the causes of Zinc deficiency.
MTs are proteins with important functions in metal metabolism and protection. 
Zinc and Copper bind to and participate in the control of the synthesis of MT proteins.
Studies indicate that the GABAergic system may be involved in ASDs, and that Zn and Cu may play a role in this system also.
 – Serum copper and zinc levels in individuals with autism spectrum disorders.
 – Analysis of Copper and Zinc Plasma Concentration and the
Efficacy of Zinc Therapy in Individuals with Asperger’s Syndrome,
Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) and
 Increased Copper in Individuals with Autism Normalizes Post Zinc Therapy More Efficiently in Individuals with Concurrent GI Disease
 – The role of zinc and copper in autism spectrum disorders.
The information in this article has not been evaluated by the FDA and should not be used to diagnose, cure or treat any disease, implied or otherwise.