Highlights of this issue

Medical genetics: a new series

The health of a developing fetus can be adversely affected by maternal medication. Although the teratogenic consequences of certain drugs have been known for years, an element of genetic susceptibility to particular effects is being defined. In the first article of a new CMAJ series about medical genetics, Janine Polifka and J.M. Friedman describe the potential role of such genetic predisposition, with particular attention to cigarette smoking, alcohol use and antiepileptic drugs. They also provide a succinct summary of suitable genetic risk counselling. In a related commentary, Alison Sinclair and Judith Hall introduce the new series with a description of the “very youngest science,” molecular medicine, the origins of which may be traced back to the 19th century science of Darwin, Wallace and Mendel.

Figure. Photo by: Christine Kenney

See pages 253 and 265

Gene patents and the standard of care

The discovery of DNA and the sequencing that has followed have created one of the most fascinating and ethically ripe areas of science. For the first time, DNA testing allows patients and their physicians screening tools for inheritable illnesses. These advances, however, are being tempered by the conventional wisdom that to encourage development, it is necessary to patent innovative technologies. A DNA sequence patent gives the holder considerable power over how the genetic material can be used. For example, the patent holder may charge a premium for testing or offer it only at specific sites. The dilemmas facing health care systems are both ethical and financial. Are Canadian physicians obliged to advise their patients of possible gene testing only available in Europe? How is our system to support the cost of increasing for-profit screening?

Two commentaries in this issue address the controversy: Donald Willison and Stuart MacLeod summarize gene patenting and its societal cost, while Richard Gold and coauthors describe the potential effects of the controversy on Canadian medical practice.

See pages 256 and 259

Neural tube defects and folic acid

Neural tube defects (NTDs) are congenital malformations of the central nervous system and result in spontaneous abortion, death in early infancy or lifetime disability. Maternal supplementation with folic acid has been known to decrease their incidence and has been recommended since 1992. In 1998 manufacturers began to fortify Canadian grain products with folic acid, despite criticism regarding the lack of firm evidence to support such practice. Although folic acid supplementation has been proven effective in randomized controlled trials, there has been little evidence of its influence on NTDs at the population level in Western countries. In this issue, Vidia Persad and coauthors in Nova Scotia and Enza Gucciardi and coauthors in Ontario used provincial data for the last 10–15 years to discern whether the Canadian policy on supplementation has succeeded in decreasing the incidence of NTDs. Both studies show a significant reduction in the total incidence of open NTDs, particularly in the late 1990s, coincident with the increased initiative to promote folic acid use and the 1998 policy to fortify flour and pasta. In a related commentary Rezan Kadir and Demetrios Economides give weight to the argument for folic acid fortification of foods.

See pages 237, 241 and 255

Genetics 101: detecting mutations in human genes

Since the discovery of the double-stranded DNA in 1953, a fascinated public has watched its mystery slowly unravel. In addition to the insight offered into the marvellous intricacy of nature, major advances in medical diagnosis and therapeutics have been gained. Genetics is becoming established as a crucial element in the pathophysiology of many of our most difficult diseases, with mutations in a chromosome's delicate structure often being the cause. In the Practice section, Alison Sinclair describes how DNA encodes information, how mutations occur and how they are identified using both existing and new methods.