RESUMO
BACKGROUND: Lichen sclerosus (LS) has been identified with increased frequency in families,often associated with HLA markers, mainly DQ7. A genetic co-etiology seems likely in this setting. Moreover, there is an association of LS with autoimmune disorders, such as the presence of anti-thyroid peroxidase autoantibodies (anti-TPO), a hallmark of autoimmune thyroid diseases. PATIENTS AND METHODS: In 3 families affected by LS, we verified their HLA markers, and identified previously undiagnosed cases of LS and autoimmune disorders. 30 individuals were examined with history, skin biopsy, HLA class I and II typing by PCR-SSP, and measurement of anti-TPO, free thyroxine and thyroidstimulating hormones (TSH) levels. RESULTS: There were 8 cases of LS, 50 % of them anti-TPO+. Autoimmune disorders were found in 40 % (total) and in 87.5 % of those affected. Most common HLA markers were B*15, B*57, CW*03, CW*07, CW*18, DRB1*04, DRB1*07, DRB4*. The three latter have been previously associated with LS. CONCLUSION: New cases of LS and autoimmune disorders can be detected in first degree relatives of patients with LS. The presence of anti-TPO antibodies strongly suggests autoimmune thyroiditis. There is intra-familial association between the haplotype HLA-B*15 -DRB1*04 -DRB4* and anti-TPO,emphasizing their link with thyroiditis. New familial approaches might help to make clear the pathogenesis of LS and its association with autoimmune diseases.