Albumin Mexico (AIMe ) in the Guatemalan Highlands FRANCIS E. JOHNSTON, ODETTE ALARCON, FRANCES BENEDICT, MIGUEL DARY, MARTHA GALBRAITH AND PATRICIA S. GINDHART T e m p l e U?ziversity, Philndelphatr, Prnnsylvtrnzu 191 22, Univcmzdnd d e l VtrLLe d r Gzintemalo, a n d the Uiizverszty of T r x n s n t Austin

K E Y WORDS Albumin . Polymorphism . Human genetics Serum proteins . Indians . Mexico.

ABSTRACT The examination of the sera of two samples of Guatemalans (total n = 386) revealed the presence of albumin Mexico ( A I M e ) among unre- lated individuals from the western highlands near the Mexican border. The frequency in the putatively less admixed sample, from Quiche, was 0.008. This is the first report of albumin polymorphism among American Indians south of Mexico. The presence of the AIMe allele among Indians of the Guatemalan highlands argues for a zone of gene flow between contiguous groups of Mexico and Guatemala. The failure to detect albumin polymorphism among lowland populations of the Yucatan peninsula may likewise be significant, but more testing of samples is required before definitive statements can be made with respect to contacts among and within highland and lowland groups.

Although genetically-determined differ- ences in the electrophoretic mobility of serum albumin have by now been shown to exist in a number of populations and family lines (Weitkamp et al., '67; Schnei- derman et al., '68; Weitkamp and Chag- non, '68; Weitkamp et al., '69a,b; Bowen et al., '71; Lie-Injo et al., '71; Lau et al., '72), polymorphic frequencies among un- related individuals have still been reported only for Indians and Eskimos of North America and Mexico. The albumin Nas- kapi allele (Allva) occurs in samples of Eskimos, in Algonkin and Athabascan- speaking Indians, and, through gene flow, in contiguous groups of the southwestern United States (Melartin, '67; Melartin et al., '68; Polesky and Rokala, '67; John- ston et al., '69; Bowen et al., '71). The albumin Mexico allele (ALMe) has been distinguished among samples of sera of Indians of the American southwest (Poles- ky and Rokala, '67; Johnston et al., '69), from Mestizos near Mexico City (Melartin et al., '67) and from Indians in other re- gions of Mexico (Lisker, '71).

Despite this broad distribution in North America and Mexco no variants have been found in populations to the south which can be called genetic polymorphisms. The few reported have displayed electropho- retic mobilities which differed clearly from

AM. J. PHYS. A N T H R O P . , ~ ~ : 27-30.

either albumin Naskapi or albumin Mex- ico; in addition, they were limited to fami- lies and apparently represent the short term persistence of a mutation.

Previous to this paper, no studies had been reported of Guatemalan samples, any groups surveyed living further to the south. However, it is significant that the testing of the sera of 263 individuals from the Yucatan peninsula (Melartin, '67), an area ecologically continuous with the Pe- ten of Guatemala, failed to detect any variability in albumin types.

We report here the results of two sur- veys of Guatemalan samples and the sub- sequent discovery of albumin Mexico among Indians of the western highlands.

The first sample consisted of 204 serums from blood donors at the Hospital General in Guatemala City. Routine screening using previously-described techniques (Me- lartin, '67; Johnston et al., '69) revealed bisalbuminemia in one individual, the pat- tern characterized by the presence of a slow-moving band in addition to the one usually observed. Repeated tests in both starch and polyacrylamide gels confirmed that this was phenotypically indistinguish- able from albumin Mexico in the hetero- zygous state (i.e., a genotype of AIA/AIMe). This finding is summarized in table 1.

The individual with the variant pheno-

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28 JOHNSTON, ALARCON, BENEDICT, DARY, GALBRAITH AND GINDHART

TABLE 1

A l b u m i n var ia t ion i n two G u a t e m a l a n s u m p l e s

Sample locale

Genotypes

A A1 ‘\/A1 M e

Allele frequency

A1 A AIMe ~~ ~ ~ ~

n f n f Guatemala City 203 0.995 1 0.005 0.998 0.002 San Antonio Ilotenango 183 0.983 3 0.017 0.992 0.008 Total 386 0.990 4 0.010 0.995 0.005

type was found to be a recent migrant to Guatemala City from San Marcos, the capital city of the Department of San Mar- cos. This area is located high in the moun- tains of the extreme western sector of the country close to the Mexican border. The accidental death of the propositus pre- vented our testing of a second sample of his serum.

The second sample examined consisted of the serum of 186 Indians from the m u n i c i p i o of San Antonio Ilotenango in the Department of Quiche. This m u n i c i p i o , with an estimated population at the be- ginning of 1970 of 7,184, is culturally Indian and with virtually no in-migration. Interviews of a sample of 197 families revealed no one born outside of its bound- aries; there is said to be very little out- migration as well. It is located also in the western highlands though not as close to the Mexican border as is San Marcos.

As shown in table 1, three unrelated individuals were found to be AlAIAlMe het- erozygotes, again determined from starch and polyacrylamide gel electrophoresis.

The frequency of the A l M e allele in the Quiche sample was 0.008 and may be used as an estimate, albeit subject to sampling error, of the frequency among relatively indigenous Indian groups of the Guate- malan highlands. The frequency among the sample from Guatemala City is much lower. However, this is a more cosmopoli- tan grouping since it undoubtedly includes individuals born in all sections of the country. What is more significant is that the individual with the variant phenotype was from the western highlands.

The existence of albumin Mexico in Mex- ico and in the Guatemalan highlands, along with its possible absence among low- land populations of the Yucatan peninsula, parallels the archeological evidence sug- gesting a zone of contact extending from

central Mexico, and further north, south- ward into western Guatemala, with less direct contact with Yucatan (Kidder et al., ’46). This distribution seems to reveal a vector of gene flow among aboriginal New World populations and may serve as a genetic marker of some value. While any possible selective advantage associated with albumin polymorphism remains to be demonstrated, the role of albumin as a transport protein suggests relationships to differential drug-binding capacities (Mel- artin, ’67), or perhaps to differential trans- port of ergosterol to sites of vitamin D synthesis.

ACKNOWLEDGMENTS

Supported in part by USPHS grant 5F3 HD-1 208-02 and by NSF grants GU 1598 and GS 3038. The advice and assistance of Dr. B. S. Blumberg is gratefully ac- know ledged .

LITERATURE CITED

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