[HL-A system in psoriasis; study of 31 families (author's transl)].

31 families with at least two psoriatic members, including sometimes three generations (4 families) have been studied looking for HL-A markers. They include 80 affected (45 females, 35 males) and 75 healthy persons. BW 17 has been found present in 58 p. 100 of the unrelated patients, versus 7 p. 100 only in the normal population (p less than 10-9). Relative risk (R.R.) for the people bearing BW 17 is 38.34. Increase of B 13 is slight and non significant. BW 16, BW 37, BW 27 are within normal range. B 12 (R.R. :0.36) seems to have a protecting effect. B 8, B 14 are also decreased. Study of way of genetic transmission favours existence of a dominant gene of susceptibility frequently associated with BW 17 and particularly with haplotype A 1, BW 17. But other genetic or environmental factors may also play a role.