Pemphigus Vulgaris in Only One of Two Monozygotic Twins

The document reported a case of pemphigus vulgaris in only one of two monozygotic twins, suggesting that genetic factors alone might not be sufficient to cause the disease. The affected twin, a 23-year-old woman, experienced severe anoxia at birth, leading to mental retardation and spasticity, and developed pemphigus vulgaris at age 11. Despite both twins having identical HLA-DR4 antigens and circulating intercellular antibodies, only the affected twin showed symptoms, indicating that additional factors, such as perinatal cerebral damage and hormonal changes during puberty, might have triggered the disease. The healthy twin, although asymptomatic, was considered at risk due to genetic predisposition and the presence of intercellular antibodies.