12.
G E N E T I C
C Y T O L O G Y
413
congenital malformations hopefully karyotyped, turned out to be
cytologically normal. So far only a handful of articles have reported
negative findings (Editorial, 1959b; Ford, 1960; Sandberg, Koepf,
Crosswhite and Hauschka, 1960; Tjio, Puck and Robinson, 1960).
Negative results have appeared in several newsletters, the Human
Chromosome Newsletter arranged by the Edinburgh group, the Mammalian
Chromosome Newsletter arranged by this laboratory, and the Animal
Cell Information Service edited by the staff of the Department of
Biophysics, University of Colorado. Since the results appearing therein
are not to be quoted without the consent of individual authors, no one
has taken the trouble to inquire around the world for compilation of
data for this valuable service. In this review I am also obliged not to
cover this subject. Anyone engaged in human cytogenetics, to avoid
wasted efforts, should consult these newsletters before studying a
special syndrome.
In Drosophila many small deficiencies or duplications are lethal and
produce malformations in the hemizygous state. They can be analyzed
by studying the giant chromosomes in the salivary glands. However,
most of the changes in chromosome structure cannot be discovered
by examining metaphase chromosomes of somatic cells. It is highly
possible that some of the congenital malformations in man are analogous to the notch wing or bar eye "genes" of Drosophila melanogaster y
but such conjectures will remain conjectures.
I . T H E
O U T L O O K
The honeymoon is over.
The law of diminishing returns also applies to scientific research,
because sensational cases become fewer and fewer as more and more
discoveries are made. Sooner or later a number of investigators will
leave this field, either discouraged because nothing exciting comes
their way, or bored because the problems are not as interesting as they
thought, or forced simply because the grant is cut. Nevertheless, since
the progress made during the past few years has been so great that
cytology has established a firm root in the realm of medicine as well
as in human genetics, we can foresee more valuable contributions from
cytogeneticists. Even though human chromosomes are not ideal for
cytological analysis, they are not as hopeless as those of the mouse or the
chicken. Furthermore, in spite of the disadvantages associated with
genetic studies of man, the tremendous number of physicians and the
formidable volume of medical knowledge compensate for the deficit.
There simply aren't so many mouse or rat doctors!
Because of heterogeneity within each syndrome, both clinically and
G E N E T I C
C Y T O L O G Y
413
congenital malformations hopefully karyotyped, turned out to be
cytologically normal. So far only a handful of articles have reported
negative findings (Editorial, 1959b; Ford, 1960; Sandberg, Koepf,
Crosswhite and Hauschka, 1960; Tjio, Puck and Robinson, 1960).
Negative results have appeared in several newsletters, the Human
Chromosome Newsletter arranged by the Edinburgh group, the Mammalian
Chromosome Newsletter arranged by this laboratory, and the Animal
Cell Information Service edited by the staff of the Department of
Biophysics, University of Colorado. Since the results appearing therein
are not to be quoted without the consent of individual authors, no one
has taken the trouble to inquire around the world for compilation of
data for this valuable service. In this review I am also obliged not to
cover this subject. Anyone engaged in human cytogenetics, to avoid
wasted efforts, should consult these newsletters before studying a
special syndrome.
In Drosophila many small deficiencies or duplications are lethal and
produce malformations in the hemizygous state. They can be analyzed
by studying the giant chromosomes in the salivary glands. However,
most of the changes in chromosome structure cannot be discovered
by examining metaphase chromosomes of somatic cells. It is highly
possible that some of the congenital malformations in man are analogous to the notch wing or bar eye "genes" of Drosophila melanogaster y
but such conjectures will remain conjectures.
I . T H E
O U T L O O K
The honeymoon is over.
The law of diminishing returns also applies to scientific research,
because sensational cases become fewer and fewer as more and more
discoveries are made. Sooner or later a number of investigators will
leave this field, either discouraged because nothing exciting comes
their way, or bored because the problems are not as interesting as they
thought, or forced simply because the grant is cut. Nevertheless, since
the progress made during the past few years has been so great that
cytology has established a firm root in the realm of medicine as well
as in human genetics, we can foresee more valuable contributions from
cytogeneticists. Even though human chromosomes are not ideal for
cytological analysis, they are not as hopeless as those of the mouse or the
chicken. Furthermore, in spite of the disadvantages associated with
genetic studies of man, the tremendous number of physicians and the
formidable volume of medical knowledge compensate for the deficit.
There simply aren't so many mouse or rat doctors!
Because of heterogeneity within each syndrome, both clinically and