Histamine N-methyltransferase functional polymorphism: Lack of associationwith schizophrenia

Histamine is a central nervous system (CNS) neurotransmitter that has been implicated in the pathophysiology of schizophrenia. Histamine N-methyltrans ferase (HNMT) terminates the neurotransmitter actions of histamine in the m ammalian CNS, and levels of HNMT activity in human tissues are controlled, in part, by inheritance. A common C314T polymorphism in the HNMT gene cause s a Thr105Ile change in encoded amino acid. The T314 allele results in decr eased levels of both HNMT enzyme activity and immunoreactive protein. There is also a polymorphic CA repeat in intron 5 of the HNMT gene. The frequenc ies of alleles for the functional C314T polymorphism and the polymorphic CA repeat were compared between 171 schizophrenia cases and 171 ethnically ma tched controls to test for possible disease association. No significant dif ference was found between the two groups in the frequency of the T314 allel e in patients with schizophrenia and controls (0.068 vs. 0.078, respectivel y). Allele frequencies for the polymorphic HNMT CA repeat also failed to sh ow significant differences between cases and matched controls. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:404-406, 2000. (C) 2000 Wiley-Liss, Inc.