Cystic fibrosis in the South West African Afrikaner. An example of population drift, possibly with heterozygote advantage.

An incidence of the genetic recessive disease cystic fibrosis (mucoviscidosis) far in 
excess of that reported recently from other countries, has been encountered 
in the South West African Afrikaner. This has probably resulted from 
the immigration of a segment of the South African Afrikaner population 
rich in the gene, into South West Africa, where, for religious 
reasons and reasons of geographical isolation, the gene has persisted and, 
perhaps, increased in frequency. Malaria, which killed many of the early 
settlers, might have selectively spared carriers of the gene, thus enriching 
its occurrence in the population. Details of patients, particularly with regard 
to the criteria of diagnosis, are given with the relevant population 
and birth figures, from which an estimate of the incidence of 
the disease and of its carrier rate has been made. Screening 
of the newborn for the condition and the compiling of a 
register of potential and obligatory carriers are also discussed. 