Department of Human Genetics
NATIONAL INSTITUTE OF GENETICS

YATA 1111. MISIMA, SIZUOKA-KEN,
canem April 10, 1962

Professor Joshua Lederberg
Department of Genetics
Stanford University
School Of Medicine
3G0 Pasteur Drive
Palo Alto, Calif.
uU, Se A.

Dear Professor Lederberg:

As to your first question, it is generally assumed by vital statisticians in
Japan that the striking excess of birth registrations in January is due to a real

seasonal variation plus an artificial bias in mis-registration, although the magnitude
introduced by this bias is not known. There seems to have been a tendency, especially

in rural areas, to register births at the end of December as if the child were
born in January of the next year, This was due to the superstition that the birth
on new year will bring good fortune to the child. However, such a trend appears
to have decreased in recent years. In this connection, there is some evidence
that some female births that took place in December 1950 were registered as of
January 1951, this again being due to some astrological predictions,

As to your second question, we have recently collected a fairy large body of
family data on ABO blood groups and secretor status in a population living in
northern Honshu. Our main interest is to test for possible prezygotic and zygotic
selection operating on these polymorphisms, The analysis is now in progress: so
far as pooled data are concerned, no effect of ABO incompatibility could be found
in this population, The data are suitable for looking for the seasonal incidence
of the progenies of incompatible matings as compared to compatible combinations;
this is one of the points of our present analysis program and we should be delighted
to cooperate with you. However, it will take at least one year more until we
could get some final conclusions to compare with your data, Anyhow, our present
data would provide some results of retrospective nature, so that, if they proved

to be positive, a new project of prospective study on the newborns would be
considered as the next step.

The Hokkaido data we collected some years ago are not suitable for our purpose
because they provide no information on the blood groups of the progenies. Since
the population of the Ainu is very small in size and they are rather isolated,

the possibility of stratification due to introgression from the Ainu seems to be
negligible,

Sincerely yours

(3, Matsunaga, M, D.)

‘ poyvas LY W

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aT

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