16 Hemopoietic reserve. It was of interest to determine whether the hemopoietic reserve of the exposed Marshallese was equalto that of the unexposed group. Means were soughtto stimulate or challenge the marrow in regard to white cellular elements, erythroid cells, or platelets, but no 2) MN System: This blood group system was distributed as follows. No. M MN feasible methods have been found. However, ad- vantage was taken of a possibility that effects of the natural stress of menstruation and childbearing in the women .5 to 45 years of age might be reflected in differences in levels of their peripheral blood elements. The blood levels in this group of females were compared with those in the same age group of unexposed females, and the differences were then compared with the differences between exposed and unexposed men in the same age groups. Irradiated women and men, 15 to +5 years of age, were found to show the following percentage differences from the unexposed women and men of the same age group: neutrophils, females —5%, males +3%: lymphocytes, females —6%, males —15%; platelets, females —6%, males —7%; hematocrit, females +2%, males —6%. From these data, it did not appear that exposed women showed any lowerlevels of peripheral blood elements than did the exposed men compared with the unexposed groups, and thestress of these temale functions did not appear to cause any noticeable effect. Hematological Studies of Genetically Determined Traits. Blood grouping studies. ‘The following is taken from a report by Sussmanetal.'® on blood groupings in the Rongelapese. 1) ABO System: The groupings in this system were asfollows. Group No. % Gene FREQUENCY CO 75 58.1 0.762 pe=0.789 Ay A, 24 0 18.6 0 0.114 9e= 0.116 B 19 15.0 0.093 r,=0.095 A,B AB 10 L 7.4 0.8 N total absence of A, genes in Eastern Asia, Australia, and Indonesia has been repeatedly noted.‘*:'* Inquiry into the family backgroundofthe single A,B native failed to reveal any significant information leading one to suspect admixture. 101 GENE FREQUENCY 6.2 15.5 0.14 78.3 0.86 The low frequency of the M gene has been noted in the Marshall Islanders by manyinvestigators.’° The frequencies obtained in this study are among the lowest encountered. 3) Rh-Hr System: A most unusual distribution was noted in this system. Tests were performed with anti Rh, (D), rh’ (C), rh” (EB), hr’ (c) and hr” (e} sera. The results are as follows. PHENOTYPE No. % CHROMOSOME FREQUENCY Rh, Rh, 126 97.7 R'=98,5 Rh.rh 3 2.3 The chromosomefrequency of 98.5% for R' is the highest reported for any ethnic group. The complete absence of any rh negative persons in these andrelated series leads one to suspect that the true genotype of the bloods giving a positive reaction with anti hr’ (c) serum is most probably R'R°. The occasional finding of an Rh, person by Simmons”supports this interpretation. In the presentseries of 125 there were no bloods that reacted with rh” (E) antiserum. Table 7 Case The unusual finding ofa single A,B was verified by testing with several absorbed B antisera, as weil as with the lectin of Doltchos b:florans.'’ The 8 20 % No. Age Sex WBC (xX10%) Neut. (107°) Lymph. Plate. 1.7 2.1 2.8 1.8 3.2 1.7 2.2 199 198 316 247 219 197 218 99 2.7 399 383 (9107) 6% 107) EXPOSED 68 73 12 16" 58 30 il 53 22 23 42 63 63 54 M M F M F F M 4.6 4.7 4.5 4.5 5.6 5.5 5.6 2.2 2.3 1.6 2.2 2.2 3.7 3.2 UNEXPOSED 878 854 39 38 * Ailingnae. M F 3.0 3.1 2.2 2.2

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