SUMMARY Three hundred and thirty-four monoclonal gammopathies were detected in the sera of 30 279 adults from Finistere.Monoclonal gammopathies (MG) are more common in Finistere than in Paris and their distribution is not homogeneous. IgG paraproteins are particularly common in the northeast of Finistere whereas IgM paraproteins are more common in the southwest. Family studies and the high degree of inbreeding would support the hypothesis that there is a genetic predisposition to develop MG but the occurrence of paraproteins among three non-consanguineous couples seems to favour the existence of an environmental factor.

Forty-eight unrelated patients with idiopathic hemochromatosis were found to have a significantly higher frequency of three HLA antigens (A3, B7 and B14) than 591 healthy controls. A significant association between HLA haplotypes and disease segregations was demonstrated in 14 family studies. A recessive inheritance of a strongly A3-linked disease gene responsible for abnormal iron stores in the heterozygote state is postulated. The lod score value (4.415 for theta = 0.025) is compatible with this hypothesis. However, the excess of HLA-identical pairs of affected sibs does not exclude the possibility of a pseudo-recessiveness due to two codominant genes both HLA-linked. For the first time, a means of screening for high risk subjects is available and therefore offers the possibility of a preventive approach.

In 237 French families with cystic fibrosis (CF) restricted fragment length polymorphisms (RFLPs) were detected by two DNA probes, XV-2c and KM-19, which are tightly linked to the CF allele. As in other European populations linkage disequilibrium is found between the haplotype B (XV-2c, allele 1: KM-19, allele 2) and the CF allele. Linkage disequilibrium alters the probability that a person bearing a given haplotype is a carrier.

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Prevention of post-transfusion malaria remains a worrying problem. Until now it was very difficult to obtain homologous antigens, and immunologic methods used to detect malaria were expensive. We tested the ready-to-use Plasmodium falciparum prepared slides using the IFA (indirect fluorescent antibody) test on 866 selected potentially dangerous donors and known malaria cases. We found that it is a simple, quick, reliable and inexpensive method that can be easily used by blood banks and improve blood transfusion safety.