BRIEF COMMUNICATION Color Blindness among Aymara in Chile’ R. CRUZ-COKE AND R. BARRERA Deparhnent of Medical Genetics, Hospital J. J. Aguirre, and Department of Genetics, School of Medicine, University of Chile, Santiago, Chile ABSTRACT Nine color blind subjects were discovered in a survey of 140 Aymaras of Arica, Chile, using as screening test a portable Anomaloscope, Ishihara tables and Hardy-Rand-Ritter plates. Pseudosisochromatic test failed on detecting four anomalous trichrornates. Seven color blind subjects revealed foreign ancestors. Also a different prevalence of defectives among subsamples was observed. Thus color blindness variability within the sample could be explained by gene flow. It is proposed to use anomaloscopes as a screening device in order to survey with accuracy color vision genes in human populations. In two recent papers published in this Journal (Adam, Doron and Modan, ’67 and Adam, ’68) the authors stressed the necessity to survey color vision in primitive populations with anomaloscopes, in order to detect with accuracy the different phenotypes of color blindness. This proposition is also supported by the human biologists of the International Biological Programme (Baker and Weiner, ’66). We have reported a complete demographic, medical and genetic survey of the Aymara speaking peoples living in the Andrean regions of Arica, in northern Chile (Cruz-Coke et al., ’66, ’67). In a preliminary survey, using Ishihara and H-R-R plates we were able to find a gradient of increasing color blindness from its absence in most primitive populations in the Sierra and Altiplano, down to moderate frequencies in suburban valleys near the port of Africa on the Pacific Ocean (Cruz-Coke, ’66, Cruz-Coke and Varela, ’66). Now we report the results of a new survey, using as a screening device, a portable anomaloscope Nagel type I (Schmidt and Haensch). We examined all the population aged 10 years and older, who inhabited the villages of Sobraya (coastal lowland valley near Arica), Chapiquifia (Sierra at 3.300 meters) and Huallatire (Highland plateau of Lauca at 4.500 meters). A small group of 25 subjects from the far distant village of Caquena, in the frontier with Bolivia, were included in our total sample of 146 males and 139 females. Every subject was examined under a Mcbeth “daylight” Lamp with the Ishihara AM. J. PHYs. ANTHROP.,31: 229-230. tables (’64) and the Hardy Rand Ritter (AO, ’57) plates. We also tested all the sample with a portable anomaloscope Nagel type 1. The Rayleigh equation was tested thrice in one eye, and a mean redgreen mixture value to the nearest integer was noted. Trichromate and Dichromate defects were explored carefully along the spectrum locus and the luminance yellow in every testee. From a total sample of 285 subjects, sixteen of them ( 6 males and 10 females >, with a normal testing of plates, were unable to perform the anomaloscope testing-twelve were schoolchildren, and four, illiterate adults. All these subjects, but three, lived in the altiplano. The anomaloscope was able to detect nine color blind subjects in the 140 remaining males examined (6.42% ) : two protanomals, three deuter anomals, one protanope and three deuteranopes. The mean red-green mixture value for the 131 normal trichromates was 43.31 with a standard deviation of 1.67, within the normal range of the Anomaly quotient. According to the expected frequencies of the ratio q : qa not one color blind female was observed. The plates of the Ishihara and the H-R-R failed to detect two protanomals and two deuteranomals, a n omission error of 44% in the sample. The table shows the distribution of the defectives by geographical regions and type of defect. The nine color blind subjects were unrelated and sporadic cases. Two were born in southern Chile. Five 1 Supported by World Health Organization Grant H.Q. W.H.O. 525/2. 229 230 R. CRUZ-COKE AND R. BARRERA TABLE 1 Distribution o f defectives by geographical region altd type o f defect Geographical regions Sobraya Chapiquifia Lauca Male 53 47 26 Protan Deutan anomaly anouia anomalv anonia 1 1 0 0 2 1 1 0 0 0 0 Total 51 1 0' - - - - - 0 - Arica gradient 12s 1 1 2 2 6 Caquena group 14 __ 0 - - - 140 1 - - Total sample 3 3 9 1 2 2 1 1 1 3 No significant difference. Mainly Bolivian sporadic travellers from Caquena, a frontier village with a population of 250. out of seven natives on the region, traced foreign ancestors from Bolivia, Peru, Spain and southern Chile. Only two individuals, a deuteranomal of Sobraya and a protanomal from Chapiquiiia, had full native parents and grandparents. Thus the existence of color blindness in this sample can be explained by a significant gene flow from immigrants. Our previous study, using the ABO system as marker genes, have showed that the cumulated Caucasian admixture of this Aymara speaking population was 13% ( m = 0.13) (Cruz-Coke et al., '67). According with the results of our investigation we think that the study of color vision variability among human populations must be reviewed, using the anomaloscope as a screening device. Certainly it is a complex and time consuming method which needs a skilled observer, but it is the sole possibility to obtain a n accurate data on the color vision structure of mankind. This need is more urgent if we consider that now, with the recent discoveries of the two blue and two green normal mutant (B1,Bz, GI and Gz) by Waaler ('67, ' 6 8 ) , the number of the color vision genes (cvp, cvP, cvd, cvD, cvt, and cvT) have mounted up to 10. If we are interested in applying evolutionary hypotheses to explain the origin and nature of color vision polymorphism, a systematic survey with anomaloscopes on the world population, must begin without delay. LITERATURE CITED Adam, A. D., D. Doron and R. Moran 1967 Frequencies of protan and deutan alleles in some Israeli communities and a note on the selection-relaxation hypothesis. Am. J. Phys. Anthrop., 26: 287-306. Adam, A. 1968 Anomals and anopes among Bedouin of Southern Sinai. Am. J. Phys. Anthrop., 28: 227. Baker, P. T., and J. S. Weiner 1966 The Biology of Human Adaptability. Oxford University Press. Cruz-Coke, R. 1966 Asociaci6n entre la oportunidad para la selecci6n natural, 10s defectos de visi6n de colores y el alcoholismo crbnico en diversas poblaciones humanas. Arch. Biol. Med. Exper., 3: 21-26. Cruz-Coke, R., A. P. Cristoffanini, M. Aspillaga and F. Biancani 1966 Evolutionary forces in human populations i n an environmental gradient in Arica, Chile. 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