Tew. tem Valle Jt Frequencyof Sabacitution of boleucine for Other Aasine Acie in Manian Hemenobin Fro 25 Muarsdalloe Subject Nu. and sox 3M 1M Age ut exposure, 90 24 Vs JF I whe uy +r 21 149,74 Iti hE “ 4a 4s Me A wf! nw toSf t i Os40ig 44M or J ay ob at Pixpaosead, ot KR EF REF Cnexpaned UES MM Wu 7 wis MM Vv ava we : bed a nt “” i 2 2417 HAG F 4 HioF tea? F at 241 MF dis al 212 ae mai F 4a) 71% Phau Nf Aoslight, but insignificant, increase inthe ise keucine substitution frequency was found in cous trols aged beqween 2Uand 31, the linear regression has a punitive slope of 0.025} 107%/ year. Except for subject No. 1547, the higher frequencies were found in samples from exposed persons, but soure of the exposed bad values in the contral range (Table 21). Vhe higher frequencies were observed more often in individuals exposed at younger ages, although the globin from subjoot Now 35, exposed atl veur. had a towisoleucine content. The find- ings are consistent with the higher leukemia ine duction, among persous exposed tos rays?and to atom bamb irradiation”! in these exposed pre: natally and at voung ages. Studies in progress stronuly suggest that the in- creased isoleucine content in the hemoglobin of exposed Marshallese is duc to base-substitution somatic mutations, The supporting data™ include analyses showing (1) that higher isalcucine sulat- 4 : abs be : . ' aon At Jo 41 Ei M ] i 4 it : om ld F BM HUF ' ' 14.4% ! 2 Averave + SEM (x 10-4) Jc : 42 F : Substitution frixqucmey (xX 14) MD 2UF Aye at prencnt, ve RS ES Rn ieee nme ge i | Sb 4 ' $47 Ss Lash hl ba} Lt tution fequencies occur in both the alpha and beta chains of hemoulobits froin exprscad persons, und (2) that conluniaation by fetal beaogalina, Shick does contain bobeuciue, could contribute oo there thaw ¢ parts por milion amino acid residues to the values reported ia Table 20. J. Genetic Studies @. Possible Radiation Effects. ‘Uhe inheritame of cadiagon-indueed mutations has bees amply demonstrated ia wenche studies on aiiaals, bat it has at been unequivocally scen in aman. Large numbers of animals are accessary te demonstrate such anel feet. and the size of the irradiated lannan populations studied is probably too small for it te le readily detected. “The largestescale human Mudy was made by Neel et al. onthe children of parcats exposed in Hiroshima and Nagasaki"! aud it slowed no cle-ecul geactic cllects. Exam. nations of the much smaller group of Marshallese s :