Section 15 — Human Genetics 



The data demonstrate the primary genetic 

 basis of taste thresholds for6-n-propylthiouracil, 

 when properly tested. They also demonstrate that 

 medication and menstruation are variables which 

 may distort the manifest thresholds. 



Supported by U.S. Public Health Service, 

 National Institutes of Health, Grant RG-9885. 



15.69. Relation Between the Blood Groups of the 

 ABO System and the Taste Sensibility to 

 Phenylthiourea (P.T.C.). Francisco G. Haro 

 (Caracas, Venezuela). 



Relation between the blood groups ABO and 

 the sensibility of taste to P.T.C. is analysed in 

 372 students of both sexes between the ages of 

 16 and 23 years. 



The method of Harris and Kalmus (1949) 

 was applied in the present investigation to deter- 

 mine the taste sensibility to P.T.C.; and the 

 slide-test with the whole blood and with an- 

 tisera A and B to determine the blood group. 



The distribution of blood groups was: 50 per 

 cent O; 32.25 per cent A; 11.3 per cent B, and 

 6.45 per cent AB. 



The threshold distribution of his age group 

 was 6-7 of the solutions of Harris and Kalmus. 



The "non tasters" and "tasters" proportion 

 was 22.6 per cent and 77.4 per cent respectively. 

 71 .42 per cent of "non tasters" were of O Group 

 (50 per cent of the whole group of students was 

 of O group) 



31 per cent of O group were "non-tasters" 

 (22.6 per cent of the whole group of students was 

 "non tasters") 



To all appearances there are correlations be- 

 tween the blood group O and the ageusia 

 ("non-tasters"). 



It is possible to explain these correlations as a 

 manifestation of linkage of the genes both re- 

 cessives? 



titative aspects of the Ai antigen might be re- 

 sponsible for the differential behavior, i.e. in- 

 fants with a strong Ai antigen more likely to be 

 affected with hemolytic disease of the newborn 

 than individuals with a weaker Ai antigen. 



A method was developed for measuring the 

 antigenic strength of erythrocytes which depends 

 on freshly drawn blood for reproducible results. 

 Density of erythrocyte suspensions, reagent, 

 complement, temperature and time of incuba- 

 tion are strictly controlled and the degree of 

 hemolysis obtained gives a measure of the antigen 

 strength. 



The data obtained thus far reveal considerable 

 variation in regard to antigen strength between 

 and among the subtypes Ai and A2. Individuals 

 whose genotype can be inferred to be AO 

 show, as a rule, little or no difference within 

 family units; there is, however, remarkable 

 variation between families. Thus, the findings 

 suggest that the alleles conditioning the sub- 

 types Ai and A2 represent an array of allelic 

 subunits within each subtype, which differ from 

 each other in that they are responsible for vari- 

 ous degrees of antigen strength, but are alike in 

 their qualitative property. In AB erythrocytes 

 the A antigen is weaker than in individuals of 

 AO genotypes, and cells of suspected homozy- 

 gous A genotype appear antigenically stronger 

 than when the same allele is in AO combination. 



Results will also be presented of a study of 

 the Ai antigen in families who have had an 

 infant with hemolytic disease of the newborn 

 due to A-O incompatibility. 



15.71. A Family Pedigree Showing the Transmission 

 of Rare and "New" Rh-Hr Genes. Lester 

 J. Unger (New York City, U.S.A.). 



This family came from a small village in 

 Puerto Rico so that the circumstances suggest 

 inbreeding. The pedigree covers three generations. 

 The rare gene involved was r° and the "new" 

 as well as rare gene was r od . 



15.70. Quantitative Variation in Antigen Strength 

 within the A Blood Types of Man and its 

 Possible Significance. F. J. Grundbacher 

 (Ann Arbor, U.S.A.). 



In hemolytic disease of the newborn due to 

 ABO incompatibility, the most frequently af- 

 fected children are of type Ai of O mothers. 

 Since the majority of ABO incompatible child- 

 mother combinations cause no obvious fetal 

 injury, the question arose whether or not quan- 



15.72. Lewis Blood Group Haptene in Human 

 Urine. D. A. P. Evans, R.B. McConnell, and 

 W. T. A. Donohoe (Liverpool, Great 

 Britain). 



It has previously been found: 



(a) that there is a pentasaccharide in pooled 



human breast milk which inhibits anti- 



Le a 0) 



293 



