Old joke: If your father doesn't have any kids, you aren't likely to either.
New scientific reality: If your father was infertile, there is a very good chance you will be also.
Advances in reproductive sciences are rewriting the rules of procreation. Many men who are genetically infertile are now able to conceive through such techniques as intracytoplasmic sperm injection, or ICSI, in which a single sperm isolated from the testes is used to fertilize the mother's egg.
Critics had feared that this procedure would allow the infertility gene to be passed along to the men's offspring, and new results reported in the July issue of Human Reproduction indicate this is, in fact, happening.
Deletions of small segments of DNA from the Y chromosome--the male sex chromosome--are the most common causes of infertility. Deletions in one particular Y region, known as AZFc, account for about 10% of cases of male infertility.
Men with the deletion produce unusually small amounts of sperm, but because ICSI requires only a few sperm, men with the defect are now able to produce children.
Geneticist David Page of the Massachusetts Institute of Technology and his colleagues studied the male offspring of three men who had an AZFc deletion but who conceived using ICSI. They found that all three boys had the same genetic defect as their fathers. They did not study female offspring, who are not affected because they do not have the Y chromosome.
The discovery raises a number of ethical issues, Page said. Perhaps such infertile males should undergo genetic screening, he suggests. Alternatively, their physicians could be encouraged to implant only embryos that are female.
Doctors Overestimate Cancer Patients' Time
Doctors who treat terminally ill cancer patients are often overly optimistic in predicting how long the patients will live, a fault that can prevent the patients from obtaining appropriate end-of-life care, according to a new study in Thursday's Cancer. In a Canadian study of 233 advanced cancer patients, physicians overestimated the predicted life span of the patients 52% of the time. The doctors' estimates were correct 25% of the time, and they underestimated the patients' longevity 23% of the time.
Physicians who predicted a survival of two months or less were most often correct, but few were comfortable predicting that patients had so little time left. But some health care programs such as hospices are accessible only to patients who are expected to live for less than two months.
A 1993 report from the National Hospice Organization in the United States found that more than 50% of patients with terminal cancer were not given access to hospice services or were referred too late to take full advantage of the support provided by hospice organizations. That study also concluded that physicians were too often over-optimistic in predicting survival.
Flu Outbreak Hits Alaska, Yukon Territory
It may not be flu season, but more than 530 people have become ill in the past month because of a flu outbreak in Alaska and Canada's Yukon Territory as the peak summer tourist season begins, federal health officials said late last week.. The Centers for Disease Control and Prevention, or CDC, said 388 tourists and tourist industry workers developed acute respiratory infections with coughs and fever between May 22 and June 21.
No one has died, but four tourists needed hospital treatment for pneumonia, the CDC said. Last summer, about 40,000 people on land and sea tours became ill, and four travelers died from a flu outbreak in Alaska and the Yukon Territory.
The CDC said people 65 or older or those with chronic health problems should be aware of the risks and symptoms of the flu and should ask their doctors about carrying antiviral medication to prevent or treat influenza.
Good News for 2-Year Transplant Survivors
Leukemia and aplastic anemia patients who survive the first two years after a bone marrow transplant have a near-normal projected life span, with only a small increase in the risk of death associated with the transplants, according to a new study from the International Bone Marrow Transplant Registry. The team studied 6,691 patients at 221 transplant centers who received the procedure for treatment of aplastic anemia or one of three types of leukemia.
They reported in Thursday's New England Journal of Medicine that those who survived the first two years had an average 89% probability of surviving another five years. That probability was slightly lower than the comparable probability for a group of carefully matched healthy people. But the researchers also found that the transplant recipients' chances of a normal life span increased slightly with every year they survived.
For Some, Work Is a Pain in the Back
Back pain is the most common reason for missing work in the United States and one of the most common causes of workers' compensation claims, according to researchers from the National Institute of Occupational Safety and Health in Cincinnati. The disorder, most of it caused by on-the-job accidents, accounts for one in four of all claims and one-third of all benefit costs, the team reported in Thursday's American Journal of Public Health.
The team interviewed more than 30,000 Americans who had worked at some point in the preceding year. They found that of 149 million workdays lost each year because of back pain, 109 million were caused by work-related problems. Workers in the lumber and building material industries had the highest risk, while construction workers accounted for the highest number of total cases, they found.
In 1992, the most recent year for which figures are available, the team found that 792,000 back injuries accounted for 24% of all work-related injuries. And nearly a third of all compensation costs--a total of $36 billion--went to victims of back injuries.
Medical writer Thomas H. Maugh II can be reached by e-mail at firstname.lastname@example.org.