American Journal of Medical Genetics Part B (Neuropsychiatric Genetics) 124B:48–49 (2004) Dinucleotide Repeat Polymorphism in Interferon-g Gene Is Not Associated With Sporadic Alzheimer’s Disease Masaya Oda, Hirofumi Maruyama, Yuishin Izumi, Hiroyuki Morino, Tsuyoshi Torii, Shigenobu Nakamura, and Hideshi Kawakami* Third Department of Internal Medicine, Hiroshima University School of Medicine, Hiroshima, Japan Various factors have been suggested to parti- cipate in Alzheimer’s disease (AD) pathol- ogy, and some inflammatory cytokines may play an important role in the development of AD. Interferon-g (IFNG), an important pro-inflammatory cytokine, is encoded by a single gene mapped to chromosome 12, one of the candidate locus of AD. The first intron in the IFNG gene represents a CA repeat poly- morphism that is possible to affect the IFNG secretion dose. We speculate that the poly- morphism may have some roles on the in- flammatory process and the pathologic change in AD, so we analyzed the IFNG gene polymorphism in 199 Japanese AD patients and 225 Japanese controls. There were no significant differences in allele frequency between the AD and control groups. We conclude that IFNG gene polymorphism is not associated with development of AD. ß 2003 Wiley-Liss, Inc. KEY WORDS: Alzheimer’s disease; inter- feron-g gene; polymorphism INTRODUCTION Alzheimer’s disease (AD) is a progressive neuro- degenerative disorder that manifests clinically with deficits in memory and cognitive functions. Among the genetic risk for AD, apolipoprotein E gene (APOE) on chromosome 19 is the only confirmed susceptibility gene contributing to sporadic late-onset AD [Corder et al., 1993; Saunders et al., 1993]. Recently, several linkage studies have reported that a locus located on chromosome 12 increases the risk of AD independent of APOE [Zubenko et al., 1999; Scott et al., 2000]. In the pathologic cascade in AD, inflammatory processes have been suggested to play some roles. Inflammatory cytokines can alter the metabolism of the b-amyloid precursor protein (APP), and interferon-g (IFNG) may trigger the production of b-amyloid peptides, inhibiting the secretion of soluble APPs in combination with tumor necrosis factor a [Blasko et al., 1999]. In genetic re- searches of cytokines associated with AD, an association of interleukin-1 gene polymorphisms with AD has been reported [Du et al., 2000]. The IFNG gene, locating near the candidate locus of AD on chromosome 12 [Scott et al., 2000], consists of 4 exons with 3 introns, with the first intron representing a CA repeat polymorphism [Ruiz- Linares, 1993]. Some of these polymorphisims may affect the IFNG secretion dose [Pravica et al., 1999], or the severity of rheumatoid arthritis [Khani-Hanjani et al., 2000]. Thus, since it is possible that IFNG gene polymorphism may have an effect on the inflammatory process, and on the pathologic change in AD, we in- vestigated the association of the polymorphism with AD. MATERIALS AND METHODS The subjects consisted of 199 sporadic AD patients (using NINCDS-ADRDA criteria, 130 women and 69 men; age range 45–93 years; mean 71.2, SD 10.4) and 225 control subjects (117 women and 108 men; age range 50–94 years; mean 64.7, SD 10.5). All subjects were Japanese, and there was no significant difference in the mean age and gender ratio between the AD and control groups. Informed consent was given by all subjects. Genomic DNA was extracted from peripheral blood by standard methods. The region of the IFNG gene containing the CA repeats was amplified by polymerase chain reaction (PCR). Primers for the PCR were 5 0 -AGACATTCACAATTGATTTTATTCTTAC-3 0 and 5 0 -CCTTCCTGTAGGGTATTATTATACG-3 0 , and the former one was labeled with [g- 32 P]ATP. The PCR products were electrophoresed on a polyacrylamide gel and the sizes were determined by comparison with a standard M13 sequencing ladder. The number of CA *Correspondence to: Hideshi Kawakami, M.D., Third Department of Internal Medicine, Hiroshima University School of Medicine, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. E-mail: hkawakam@hiroshima-u.ac.jp Received 13 August 2001; Accepted 11 March 2003 DOI 10.1002/ajmg.b.20097 ß 2003 Wiley-Liss, Inc.