TS	Tourette syndrome
TD	Tic disorder
TTD	Transient tic disorder
CTD	Chronic motor or vocal tic disorder
OCD	Obsessive–compulsive disorder
ASD	Autism spectrum disorder
ADHD	Attention-deficit/hyperactivity disorder
CSTC	Cortico-striato-thalamo-cortical
DA	Dopamine
GABA	γ-aminobutyric acid
Vit D	Vitamin D
VDR	Vitamin D receptor
UVB	Ultraviolet B
GDNF	Glial cell line-derived neurotrophic factor
YGTSS	Yale Global Tic Severity Scale
HPLC	High-performance Liquid Chromatography
MS/MS	Tandem Mass Spectrometry
HC	Healthy Controls
IU	International Units
Vit B6	Vitamin B6
PLP	Pyridoxal-5′-phosphate
PN	Pyridoxine
PM	Pyridoxamine
PL	Pyridoxal
PNP	Pyridoxine 5′-phosphate
PMP	Pyridoxamine 5′-phosphate
RA	Retinoic acid
RAR	Retinoic acid receptor
UL	Upper intake level
HPA	Hypothalamic–pituitary–adrenal
ACTH	Adrenocorticotropic hormone
Mg	Magnesium
Zn	Zinc
Cu	Copper
MRI	Magnetic resonance imaging
FDA	Food and Drug Administration
AAN	American Academy of Neurology
DBS	deep brain stimulation
CBIT	Comprehensive Behavioral Intervention