OBJECTIVE: Catechol O-methyltransferase (COMT) inactivates
catecholamines by methylating their m-hydroxy group. Some previous studies
using biochemical methods have found higher levels of COMT activity in
schizophrenic patients. Recently, the genetic polymorphism that underlies
variation in COMT activity, which results in the creation of a NlaIII
restriction site in the low-activity allele, has been elucidated. METHOD:
This study investigated this polymorphism in 78 unrelated schizophrenic
patients and 78 comparison subjects matched for age and ethnicity.
High-molecular-weight DNA was isolated from lymphocytes with routine
procedures, and each individual was typed for high and low COMT activity.
RESULTS: The frequency of the NlaIII polymorphism was 0.51 in the
schizophrenic patients and 0.53 in the comparison subjects, and no
significant allelic or genotypic associations were observed. CONCLUSIONS:
There was no evidence for variation in COMT activity between a group of
schizophrenic patients and matched comparison subjects.