Both low copy number in 22q11DS and reduced COMT expression due to the presence of a COMT 675A allele [14] have been associated with neuropsychiatric symptoms, including anxiety and Obsessive Compulsive Symptoms [17, 18]. Cerebrospinal fluid neurotransmitter and metabolite levels were not altered in our patient. Although this finding might have had treatment implications, it was not surprising. A recent report showed no alterations in these studies in psychiatric patients with COMT gene polymorphisms [19]. Another study found CSF dopamine changes in Restless Legs Syndrome, but mainly in the presence of more severe symptoms [20]; our patient has milder motor tic symptoms. Finally, it is worth pointing out that studies have questioned the role for low COMT activity in psychiatric disorders [21, 22]. Our patient was heterozygous for the G675A COMT haplotype with duplication or the 675G, higher-expressing COMT allele. As such, the 22q11.2 duplication for this patient calls into question a unique role of low COMT activity in the etiopathogenesis of OCD or TS.
