Ocular cicatricial pemphigoid. A case report of monozygotic twins discordant for the disease
K. Bhol, I. Udell, N. Haider, J. J. Yunis, A. Mohimen, R. Neuman, C. Grasso, A. R. Ahmed and S. Foster
Department of Dermatology, Boston Mass. University School of Medicine.
OBJECTIVE: To identify the major histocompatibility complex markers and the
autoantibody associated with ocular cicatricial pemphigoid (OCP) in a
proband, her unaffected cotwin, and the children of the cotwin. Ocular
cicatricial pemphigoid is a chronic autoimmune disorder that affects the
conjunctiva and other squamous epithelium. It is associated with the major
histocompatibility complex class II alleles that are presumed to provide
enhanced susceptibility to the disease. We encountered a pair of
monozygotic female twins, one of whom has OCP. In addition to totally
identical physical appearances since birth, the two sisters have identical
blood groups. METHODS: The following studies were performed on the patient,
her unaffected cotwin sister, and her children: (1) polymorphism of major
histocompatibility complex class II genes by DNA typing, (2) sequence
analysis of DQ beta gene second and third exons, and (3) serologic
evaluation for the presence of anti-basement membrane zone autoantibodies
specific for OCP by Western immunoblot with the use of skin and conjunctiva
lysates as substrates. RESULT: Both monozygotic twins had the same HLA
haplotypes. The sequence analysis of the second and third exons of DQ beta
genes revealed no significant differences between the proband and her
unaffected cotwin. Autoantibodies specific to OCP were detected only in the
patient's serum. The serum of the unaffected cotwin and the other relatives
did not demonstrate the presence of the OCP autoantibody. CONCLUSION: This
isolated family study does not support a single-gene theory for the
development of OCP. It is most likely due to a multigene effect and
associated with environmental factors.