Abstract
Abstract: :
Purpose: To describe the co–existence of Blepharophimosis syndrome (BPES) and Duane syndrome in an affected individual. BPES represents a complex developmental malformation of the eyelids characterised by ptosis, telecanthus, epicanthus inversus and small palpebral apertures, with strabismus present in 20–25% of patients. Mutations in a forkhead transcription factor, FOXL2, are identified in up to 70% of affected individuals. BPES is further divided into type I and II depending on the presence or absence of Premature Ovarian Failure (POF) due to the pleiotropic effect of FOXL2. Duane syndrome is a congenital motility disorder of the eye, with globe retraction and narrowing of the palpebral aperture on attempted adduction. Most cases are sporadic but familial cases are reported with linkage established to 2 loci (DURS1, 8q13, and DURS2 2q31). In addition Duane syndrome occurs with other ocular and non–ocular anomalies, but no prior association with BPES has been documented. Methods: An 18 month female affected with sporadic BPES was noted to have bilateral Type I Duane Syndrome. After informed consent and DNA extraction, FOXL2 mutational analysis was undertaken. Results: A 33 nucleotide duplication (A224–234dup) within the highly conserved polyalanine tract of FOXL2 was demonstrated. This mutation was not present in either parent. Conclusions: The association of BPES and Duane syndrome represents a novel phenotype which may suggest a greater pleiotropic effect of FOXL2 in development. During the 4 to 8 week period of embryonic development, the cranial nerves, their nuclei and the corresponding innervation to the extraocular muscles develop, and the extraocular muscles are also developing and differentiating. This coincides with the period of time that FOXL2 is expressed strongly in the developing eyelids and the surrounding tissues. Forkhead genes are transcription factors and likely to be involved in signal transduction pathways. This case expands the spectrum of FOXL2 mutations associated with BPES.
Keywords: genetics • eyelid • mutations