Section 15 — Human Genetics 



15.78. New Genetic Variants in the Gc-System of 

 Human Serum. Hartwig Cleve, R. L. Kirk, 

 W. Carey Parker, and Alexander G. Bearn 

 (New York, U.S.A.). 



The group-specific components (Gc) of human 

 serum represent an additional protein poly- 

 morphism distinguished by differences in relative 

 electrophoretic mobilities. The common pheno- 

 types, Gc 1-1, Gc 2-1, and Gc 2-2 are genetically 

 controlled by a pair of co-dominant, autosomal 

 alleles, Gc 1 and Gc 2 . The distribution of the 

 Gc-alleles has been determined in various popu- 

 lations of different geographical and ethnic 

 origin. The population surveys have led to the 

 disclosure of several unusual electrophoretic 

 variants, which were identified by Immuno- 

 electrophoresis and starch gel electrophoresis. 

 Two new variants will be described, which 

 migrate more rapidly than Gc 1-1. One was 

 observed in a population of Chippewa Indians 

 and the second in a sample of Australian Abori- 

 gines from the Cape York area, and were there- 

 fore named Gc Chippewa and Gc Aborigine, 

 respectively. Family data indicated that they 

 are controlled by additional alleles at the Gc locus 

 The distribution of the various phenotypes was 

 in agreement with the assumption of population 

 equilibrium. The incidence of the variants 

 was relatively high (Gc Chi PP ewa 0.105 and 



Gc Aborigine = 0.046). Gc Chippewa has so far 

 been found only in Chippewa Indians. The 

 distribution of Gc Aborigine in a number of 

 aboriginal populations in Australia will be dis- 

 cussed and the results related to observations 

 in populations from South East Asia and Ocea- 

 nia. 



15.79. Contribution to the Genetically Determined 

 Transmission of the oti-Acid Glycoprotein 

 Variants. K. Schmid, L. Moroz and 

 K. Tokita (Boston, U.S.A.). 



At the Second International Conference of 

 Human Genetics in Rome we reported on the 

 relative incidence of the different oci-acid glyco- 

 protein patterns in normal white adults. In the 

 present study, cci-acid glycoprotein was isolated 

 from plasma of 13 members of a family of 

 Italian origin and analyzed by starch gel electro- 

 phoresis at pH 2.9, resulting in most cases in a 

 pattern with six bands. This binding strongly 

 supports the concept that the cci-acid glyco- 

 protein variants are genetically determined. 

 Further evidence was obtained from the cor- 

 responding analysis of identical twins. 



In continuing this investigation, ati-acid 

 glycoprotein was prepared from plasma of 44 



white adult patients with various diseases and 

 subjected to the same analytical procedure. The 

 blood level of this protein was elevated in most 

 patients, the maximum increase amounting to 

 300 per cent. The relative incidence of the ox- 

 acid glycoprotein patterns was found to be 

 very similar to that of normal white adults and, 

 as judged from the relatively small number of 

 analyses, independent of the plasma concen- 

 tration of this protein. Thus, the genetic trans- 

 mission of the cci-acid glycoprotein variants 

 appears to be well established. 



Supported by NIH grants GM-10374-01 and 

 A-3564-C2. 



15.80. The Genetically Determined cci-Acid Glyco- 

 protein Variants. K. Tokita and K. Schmid 

 (Boston, U.S.A.). 



The cci-acid glycoprotein patterns obtained 

 by starch gel electrophoresis at pH 2.9 appear 

 too complex for genetic evaluation because of 

 the large number of bands observed (5, 6, 7 

 and 8, respectively). In an attempt to arrive at 

 simpler patterns, ai-acid glycoprotein was in- 

 cubated with neuraminidase and subjected to 

 starch gel electrophoresis at pH 4.8. The en- 

 zymatically modified glycoprotein derived from 

 pooled normal plasma revealed a pattern with 

 two main bands of almost equal color intensity 

 and a minor faster moving band( 1 ). 



In the present study cci-acid glycoprotein was 

 isolated from normal adults, treated with neura- 

 minidase and analyzed by starch gel electropho- 

 resis at pH 4.8. Three types of patterns were 

 noted : the first type exhibited the maximum color 

 intensity at the slowest moving band and the 

 second type at the center band. The third type 

 showed the slow moving and the middle band to 

 be almost equal in color intensity and very 

 similar to that of pooled normal cci-acid gly- 

 coprotein. As judged by the number of analyses 

 carried out (65) the relative incidence of these 

 three types were found to be approximately 10, 

 50 and 40 per cent, respectively. Additional 

 results obtained from the corresponding study of 

 identical twins supported the concept of the 

 genetically determined transmission of the oti- 

 acid glycoprotein variants. 



Supported by NIH grants GM-10374-01 and 

 A-3564, C2. 

 1. Nature, 190, 630 (1961). 



296 



