P7.75 Clinical significance of the HLA-DR11 positive subset in patients with alopecia aerata

C. Marques Da Costa^a, J.J. Stene^a, E. Dupont^b, M. Vandercruys^b, M. Hidajat^b,
M. Andrien^b.

^aDept. of Dermatology (St. Pierre Hosp.) and ^bImmunology (Erasme Hosp.) Université Libre de Bruxelles, Belgium

Many studies have shown an association of alopecia aerata (AA) with HLA-DR11. In view of the fact that in several autoimmune diseases such as psoriasis and diabetes, the existence of an HLA association indicates a clinical evolution (i.e. earlier onset of the disease) which is different from the forms that are not associated with HLA, we investigated various parameters in a group of 88 patients with severe AA. This included 32 DR11 positive and 56 DR11 negative patients. Compared to the frequency (22%) of DR11 in 99 healthy subjects belonging to the same ethnic background, a significant association (p = 0.01; RR =2.1) was found. However the analysis by DNA subtyping of the frequency of the various DR allotypes revealed a similar distribution in the diseased and in the control groups. In the DR11 positive subset, age of onset (16.4 ± 2.6 years) occurred significantly earlier than in the DR11 negative subset (27.3 ± 2.3 years ; p =        0.01). The analysis of the clinical course of patients was performed by considering two groups of patients, those with severe AU/AT forms and those not belonging to this peculiar subset. There was a slight although not significant excess of severe AU/AT cases in the DR11 pos group (n=17; 53%) as compared to the DR11 negative which included only 24 patients (43%).

It is concluded that the DR11 mediated form of AA includes patients with an earlier onset of disease, the later involving a slightly increased proportion of severe forms, an observation compatible with the existence of non HLA genes in addition to HLA genes in the development of the disease.