The variant form of DARC stops the growth of Plasmodium vivax, one of the four parasites that can cause malaria.

ECONOMIST: AIDS

They found the women who had miscarried were much more likely to carry the variant form of the NOS gene.

BBC: Miscarriage gene identified

The upshot, when the team crunched the numbers, was that the variant form of DARC may be responsible for 11% of the African epidemic.

ECONOMIST: AIDS

The WHO expressed concern about what it called "exposure worldwide" to mad cow disease and its fatal human form, new variant Creutzfeldt-Jakob Disease (vCJD).

CNN: New BSE case in Germany

The beef-on-the-bone ban was imposed on the industry in 1997 after fears over new variant CJD, suspected of being the human form of mad cow disease.

BBC: News Online

The finding that may cause most controversy, however, is that in the Asian groups there has been strong selection for one variant of a gene that, in a different form, is responsible for Gaucher's disease.

ECONOMIST: Human evolution

It is alleged that the Buffalo Grill chain continued serving beef from Britain after it was banned in the European Union and that this may have been the cause of cases of the human form of mad cow disease (BSE), known as variant CJD.

BBC: French restaurant chain in BSE probe