AFHS General Program Meeting - 4 May 1998
by Dr. Brian Lowry, former Director, Alberta Childrens' Hospital
Department of Medical Genetics
See also current AFHS
Theory and Terminology
Dr. Lowry began by briefly reviewing the theory and terminology
of genetics as it had developed from the time of Mendel onwards.
He introduced the audience to the 46 human chromosomes with a couple
of slides showing the complement of a female and a male, pointing
out the difference in the appearance of the sex chromosomes; he
then went on to discuss the idea of sex-linkage and its significance
in some diseases.
The central message of his talk was that, at this moment in the
history of medicine, there is absolutely no substitute for the detailed
and careful family medical history (a concept that should be clear
to genealogists) when it comes to assessing the possible risk of
a genetic disorder for any given patient.
He showed numerous family trees which showed the occurrence of
various disorders through successive generations, and he showed
slides of the effects of many of these disorders. He said that it
is by the analysis of many family trees in affected families that
it has been possible to calculate the tables used by medical geneticists
to predict the probability of any given person in an affected family
getting the disease in question.
He discussed some difficulties in this procedure that genealogists
could readily relate to:
- the further back one goes on the family tree the more difficult
it is to be sure of the diagnosis in terms that have any meaning
for modern physicians
- many of the diseases that affect children lead to their death
in infancy, leaving the paediatric geneticist and the genealogist
with nothing more substantial than "di.": "died
- genetic disorders which do not show themselves till late in
life have been difficult to identify as being of hereditary origin
until recently, and even now are easy to overlook
Dr. Lowry showed how useful it has been for geneticists to study
closed communities like the Hutterites to study the effects of consanguinity
in the transmission of hereditary diseases; he showed some remarkable
medical family trees (no names or dates, just squares and circles
for males and females) to illustrate this point.
Dr.Lowry's talk was followed by an energetic and prolonged question
period, evidence of the widespread interest in this topic on the
part of the members of the Society. Perhaps the most telling comment
was that he had concentrated on the negative effects of genetic
inheritance to the exclusion of the positive manifestations of this
wonderful process of Nature; he ruefully conceded the point, saying
that doctors, by virtue of their training, have a rather gloomy
view of life.