7
children born to an exposed parent or parents
have shown, on the basis of incidence of gross
anomalies, no evidence of inherited radiationinduced mutations.
Theprincipal aberrations noted in Marshallese
adults and children have been bilateral shortening
of the fifth finger, prominent headof ulna, dislocated wrist, enlarged cornea, tortuosity of retinal
may take several generationsto affect the phenotype, recognition of their radiation etiology may
be extremely difficult. Neel et al. are at present
carrving out moresophisticated studies in the Japanese, concerned with the occurrenceof variant
forms of 24 serum proteins and erythrocyte enzymes. He and Dr. R.E. Ferrell kindly consented
to examine blood samples collected in 1974 from
187 Marshallese children and parents (exposed
vessels, asymmetry of face. congenital nystagmus,
and pigmentation of the cornea. Studies of familial
patterns of such defects have not been done; they
are not related to exposure.
The possible increase in miscarriages andstillbirths among the exposed women duringthefirst
5 vears maylead to speculations that radiation in-
duced lethal mutations in germ cells of the ovary
or, less likely, in sperm cells.* The presence of
chromosomeaberrations in peripheral blood lymphocytes in the Marshallese 10 years post expo-
sure, and the possible somatic mutation in the
hemoglobin, described above, support speculations
that mutations in the germ plasm occurred and
might be detected in the offspring by moresensi-
tive tests. However, in view of the relatively small
dose of radiation and the smallsize of the population, on a@ priort grounds a clear-cut demonstration
of a genetic effect of radiation in the children born
to exposed parents would seem unlikely. Never-
theless, given the nature of the circumstances, it
has been deemeddesirable to make every effort to
collect such data. Since recessive combinations
“About one-half the miscarriages occurred in exposed women
married to unexposed men.
and unexposed). The results, summarized below,
included no significant findings indicating radiation-induced mutations.
b. The Frequency of “‘Rare'’ Protein Variants.
The blood samples mentioned above were sub-
jected to electrophoretic analyses for polymorphisms andrare variants of proteins and erythrocyte enzymes.82 The findings were summarized by
Neelet al.8? as follows.
“Blood specimens from a sample of 187 Marshall Islanders were studied with reference to variants of 24 serum proteins and erythrocyte enzymes.
Six of the traits studied exhibited genetic polymorphisms (adenosine deaminase, phosphoglucomutase, acid phosphatase, 6-phosphogluconate
dehydrogenase, haptoglobin, group specific component). There was in addition one‘rare’ variant
(of albumin) in 4047 determinations. These results
on rare variants have been combined with those of
others on Micronesians, and the frequency of rare
variants in Micronesians compared withthefrequencies in West European Caucasians, Japanese.
and Amerindians. There are many difficultiesin
such comparisons, and, although the observedvalues for the four ethnic groups differ by a factor of
Table 22
r
*
-
-
Gene Frequencie#for Six Genetic Polymorphismsiri the Marshall Islands®?
a Phenotype
System
" i “4
Adenosinedeaminaee =i ts
Group specific component
Haptoglobin*
a
Phosphoglucomutase, **
Acid phosphatase
,
6-Phosphogluconate dehydrogenase
_
.
GT
186
56
156
_A
101
164
2-1
18
2
0
50
93
26
2,
32
ft
AB
B
2
0
73
Total
Genefrequency
185
.
168
177
184
b>” 485
185
*
ADA!
= 0.951
APA
= 0.743
Gc}
Hp!
PGM,!
= 0.839
= 0.579
= 0.912
6-PGDA = 0.943
*The Hp® type was observed in 4 individuals.
**Two examples of the PGM phenotype 2-7 and a single phenotype 1-7 were observed (PGM;,7 =0.008).