The genetic resistance may be beneficial to families as those with the gene are both unlikely to suffer from disease and unlikely to carry the disease home. Paul Schliekelman, author of the study, says the research was inspired by personal experience after catching stomach flus from his daughter three times over a six-month period.

Schliekelman used mathematical models to calculate the possible effect of kin selection on natural evolution. Natural selection is typically seen as survival of the fittest', but in this case it might be more accurate to say survival of the fittest families,' says Schliekelman.

His research led to the following conclusions:

There exists a strong tendency to catch infectious diseases from family members. If a relative has a gene that gives resistance to a disease, it would benefit other relatives because they would be less likely to catch the disease. Genes that offer resistance to infectious diseases will tend to cluster in families. Therefore, the resistance genes in a family help each other out and natural selection in their favor can be dramatically increased.

This model may prove useful in understanding the spread of deadly diseases and may alter the long-term natural selection of certain genes in a population. Studying the genetic behavior of these diseases could be an important step towards understanding the evolutionary history of infectious disease resistance.

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The researchers also pretreated mice with cyclopamine before injecting human glioblastoma cells into their brains, resulting in cancer cells that failed to form tumors in the mice.

Other researchers have shown that radiotherapy fails to kill all cancer stem cells in glioblastomas, apparently because many of these cells can repair the DNA damage inflicted by radiation. The Hopkins team suggests that blocking the Hedgehog pathway with cyclopamine kills these radiation-resistant cancer stem cells.

In previous laboratory experiments, Eberhart used cyclopamine to block Hedgehog using medulloblastoma cells, the most common brain cancer occurring in children.

Along with childhood brain cancers, cyclopamine has shown early promise in treating skin cancer; rhabdomyosarcoma, a muscle tumor; and multiple myeloma, a cancer of the white blood cells in bone marrow.

What excites me is that we have taken things we learned about Hedgehog signaling in these relatively rare childhood brain tumors and translated them into an even more aggressive adult tumor, Eberhart said.

More than 10,000 Americans die annually from glioblastomas. Radiation is the standard therapy for the disease, and several years ago, the U.S. Food and Drug Administration approved adding the drug temozolomide to radiotherapy because the combination provided a small survival increase.

This is an incredibly difficult tumor to treat, says first author Eli E. Bar, Ph.D., a postdoctoral fellow. Survival for glioblastoma has not changed much in 30 years. With the addition of temozolomide, survival got bumped from 12 months to 14 or 15 months.

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