239 Letters to the Editor receptor variants in the human population. Nature 358: Thus, we were not able to replicate the findings of 149–152 Grice et al. (1996). JOHANNES HEBEBRAND,MARKUS M. NO ¨ THEN, Address for correspondence and reprints: Dr. Johannes Hebebrand, Clinical Research Group, Department of Child and Adolescent Psychiatry, Philipp’s ANDREAS ZIEGLER,BIRGIT KLUG,HELGE NEIDT, University of Marburg, 35033 Marburg, Germany. E-mail: hebebran@ KATJA EGGERMANN,GERD LEHMKUHL,FRITZ post.med.uni-marburg.de POUSTKA,MARTIN H. SCHMIDT,PETER PROPPING,  1997 by The American Society of Human Genetics. All rights reserved. 0002-9297/97/6101-0033$02.00 AND HELMUT REMSCHMIDT Clinical Research Group Department of Child and Adolescent Psychiatry Philipp’s University of Marburg Marburg, Germany Am. J. Hum. Genet. 61:239–241, 1997 Acknowledgment Exclusion of Atypical Vitelliform Macular Dystrophy from 8q24.3 and from Other Known Macular This study was supported by the Deutsche Forschungs- gemeinschaft. Degenerative Loci To the Editor: Atypical vitelliform macular dystrophy (VMD1; OMIM References 153840) is an autosomal dominant disorder that can Catalano M, Nobile M, Novelli E, No ¨ then MM, Smeraldi E lead to blindness. VMD1 is characterized by complete (1993) Distribution of a novel mutation in the first exon of penetrance but extremely variable expressivity, includ- the human dopamine receptor D4 gene in psychotic patients. ing with regard to age of onset and rate of progression. Biol Psychiatry 34:459 – 464 The findings for VMD1 include (1) macular and/or pe- Cichon S, No ¨ then MM, Catalano M, DiBella D, Maier W, ripheral retinal lesions that may be small and yellow, Lichtermann D, Minges J, et al (1995) Identification of intermediate and white, or large and depigmented, and two novel polymorphisms and a rare deletion variant in (2) peripapillary abnormalities that are initially in the the human dopamine D4 receptor gene. Psychiatr Genet temporal nerve bundle but that progress circumferen- 5:97–103 tially. The phenotype of VMD1 is similar to that of Best Grice DE, Leckman JF, Pauls DL, Kurlan R, Kidd KK, Pakstis disease (VMD2; OMIM 153700); however, the macular AJ, Chang FM, et al (1996) Linkage disequilibrium between lesions of VMD1 and VMD2 are clinically distinguish- an allele at the dopamine D4 receptor locus and Tourette syndrome, by the transmission-disequilibrium test. Am J able (Mintz-Hittner et al. 1984). Hum Genet 59:644–652 An early linkage study in one large family reported Hebebrand J, No ¨ then MM, Lehmkuhl G, Poustka F, Schmidt linkage between the VMD1 locus and the soluble gluta- M, Propping P, Remschmidt H (1993) Tourette’s syndrome mate-pyruvate transaminase (GPT) locus, with a maxi- and homozygosity for the dopamine D3 receptor gene. Lan- mum two-point LOD score of 4.3 at 5% recombination cet 341:1483 (Ferrell et al. 1983). At that time, the GPT locus had Lichter JB, Barr CL, Kennedy JL, Van Tol HHM, Kidd KK, been mapped tentatively to chromosome 16 (Wijnen and Livak KJ (1993) A hypervariable segment in the human Meera Khan 1982). Recently, however, we have mapped dopamine receptor D4 (DRD4) gene. Hum Mol Genet 2: the GPT locus to the long arm of chromosome 8 and 767–773 have developed a PCR-RFLP assay for GPT typing (So- No ¨then MM, Cichon S, Hemmer S, Hebebrand J, Remschmidt hocki et al. 1997). All previous GPT typing was by deter- H, Lehmkuhl G, Poustka F, et al (1994a) Human dopamine D4 receptor gene: frequent occurrence of a null allele and obser- mination of the serologic phenotype only, and, because vation of homozygosity. Hum Mol Genet 3:2207–2212 there are dramatic quantitative differences between the No ¨ then MM, Hebebrand J, Knapp M, Hebebrand K, Camps three common GPT serologic phenotypes (Welch 1972), A, von Gontard A, Wettke-Scha ¨ fer R, et al (1994b) Associa- GPT serotyping was difficult. Furthermore, within the tion analysis of the dopamine D2 receptor gene in Tourette’s last 4 years, several other loci associated with autosomal syndrome using the haplotype relative risk method. Am J dominant macular degeneration (adMD) have been Med Genet 54:249–252 mapped to chromosomal sites (table 1). Given the re- Spielman RS, McGinnis RE, Ewens WJ (1993) Transmission fined localization of the GPT locus and given the addi- test for linkage disequilibrium: the insulin gene region and tional mapped loci for adMD, it was important to re- insulin-dependent diabetes mellitus (IDDM). Am J Hum examine the localization of the VMD1 locus in the pre- Genet 52:506 – 516 viously studied family. Van Tol HHM, Wu CM, Guan H-C, Ohara K, Bunzow JR, Civelli O, Kennedy J, et al (1992) Multiple dopamine D4 To further characterize the VMD1 locus, we recently / 9a2d$$jy27 07-09-97 14:20:50 ajhga UC-AJHG