Scientific visits to the Aland Islands.

Three research trips performed by the Stockholm teams in 1957, 1977, and 1992 are described in this paper. At the 1957 visit we showed that the family members of the original family and a few others, as described by von Willebrand, had the same coagulation defects as the Swedish patients with von Willebrand's disease (vWD) (prolonged bleeding time, low FVIII levels and a normal platelet factor 3) and that fraction I-0 normalized the defect. At the 1977 visit we showed that the bleeding disorder described in many papers by von Willebrand and collaborators over the years could be divided into four different forms: the pure vWD; two platelet function defects, i.e. a pure cyclooxygenase defect (no platelet aggregation at addition of arachidonic acid solely); an aspirin-like defect, generally called a cyclooxygenase defect; and a mix between vWD and the cyclooxygenase defect. At the 1992 visit members of four families with genuine vWD (including the original family) of the Aland Islands were screened for mutations of the 'hot spot' regions, exons 18, 28, 32, 43 and 45, of the von Willebrand factor (vWF) gene found in Sweden. One cytosine deletion in exon 18 was detected in all the families. Linkage analysis and genealogical studies suggest that the deletion in these families probably has a common origin also with the Swedish patients. Apart from the deletion in exon 18, two close transitions G --> A at S1263 and C --> T at P1266 in exon 28 on the same chromosome, were identified in one individual, who married into the original family, and his two children. These mutations are probably due to a recombination between the vWF gene and its pseudogene, since both transitions are also present in the same location in the pseudogene.