Other Comments: The PCR reaction was performed on 80 ng of genomic DNA using 100 pmoles of each oligonucleotide primer. The samples were processed as described (4) except that the denaturation cycle at 94°C was extended to 1.4 minutes. The tetranucleotide repeat was based on a (ATTT)1I sequence. References: 1) Roebroek,A.J.M. et al. (1985) EMBO J. 4, 2897-2903. 2) Weber,J.L. and May,P.E. (1989) Am. J. Hum. Genet. 44, 388-396. 3) Harper,M.E. et al. (1983) Nature 304, 169-171. 4) Weber,J.L. et al. (1990) Nucl. Acids Res. 18, 4637. Dinucleotide repeat polymorphism at the human CTLA4 gene Mihael H.Polymeropoulos, Hong Xiao, Denise S.Rath and Carl R.Merril National Institute of Mental Health Neuroscience Center, St. Elizabeths Hospital, Room 131, 2700 Martin Luther King Avenue, Washington, DC 20032, USA