Serum ferritin level and tic severity

Another connection to oxidative stress due to lowered CBS activity and tics severity:

Conclusions: Our data suggest iron deficiency may be associated with more severe tics with higher impact on TS children, independent of the presence of OCD, ADHD, or anxiety.

Iron supplementation showed a trend towards improvement of tic severity upon follow-up.

CBS is a heme-enzyme, which means it depends on iron status and sufficiency of heme synthesis. Heme is used as a sensor for oxidative stress in this enzyme.

It’s a no brainer that iron deficiency should lead to reduced CBS activity and as a result to higher oxidative stress, because cysteine synthesis is impaired.