Does Genetics Really Affect Us All? Presidential Guest Speaker
JUDITH G. HALL, MD, MS, FAAP, FRCP(C), FCCAG, FABMG*
Genetics affects us professionally and personally. Genetic disorders may be chromosomal, single-gene, or multifactorial. Extra or missing chromosomes are associated with multiple system involvement. One can map on which chromosome certain features lie, such as missing digits. Single-gene dominant mutations are related to advanced paternal age, while chromosomal disorders appear with advanced maternal age. DNA and RNA studies concern the molecular basis of single-gene disorders. Cloning, genetic engineering, enables the creation of hormones by making a DNA copy. Studying gene linkage permits predicting various diseases where clinical signs appear later. Multifactorial disorders are interactions of genetic and environmental factors, such as dislocated hips.
One should distinguish a) malformations where parts never formed correctly, often genetically based, such as neural tube defect; b) disruptions, where parts formed normally, but were then disrupted, as amputation caused by amniotic band constriction; c) deformations, where parts formed normally, then were deformed, as club feet seen with neural tube defect; and d) dysplasia, disorders involving one tissue, usually genetically based.
Genetic counseling is an educational process involving making pre- and postnatal diagnoses and advising the family about the natural history of the disorder, recurrence risks, therapy, and prevention.
*Department of Medical Genetics, University of British Columbia, 4490 Oak Street, Vancouver, British Columbia V6H 3V5