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We divide the CCDDs into disorders that primarily affect vertically acting extraocular muscles and those that primarily affect horizontally acting extraocular muscles. The various forms of congenital fibrosis of the extraocular muscles (CFEOM), congenital ptosis, and Marcus-Gunn primarily affect vertically acting muscles, and we propose that these disorders result primarily from aberrant
development of the oculomotor and/or trochlear nuclei. The various forms of Duane syndrome, horizontal gaze palsy, and Moebius syndrome all fall within the second group, and we propose that these CCDD syndromes result primarily from aberrant development of the abducens nucleus.
Many of the forms of CCDD are inherited, and the laboratory's approach to understanding these syndromes begins with the identification and clinical classification of affected families and individuals. This ongoing process has led to the description of several new strabismus syndromes and to collaborations with clinicians worldwide. We use genetic linkage analysis to define and refine the chromosomal localization of the different CCDD syndromes, and positional cloning techniques to identify the mutated genes. The genetic work is complemented by neuropathologic and high-resolution orbital MRI investigations, conducted in collaboration with Dr. Joseph Demer at UCLA, to uncover anatomic defects and to guide the choice of candidate genes for future study.
Using this approach, our laboratory has identified and mapped three CFEOM loci (FEOM1-3), two Duane loci (DRRS, DURS3), and one ptosis locus (PTOS1) and we have identified the FEOM1, FEOM2, DRRS (Duane with radial ray anomalies) and HGPPS (Horizontal gaze palsy with progressive scoliosis) disease genes.
Members of the lab are currently using positional cloning techniques to identify additional CCDD genes, incluing the FEOM3, PTOS1 and DURS2 genes.
Please use the links on the left to view information on the eye disorders we study and for detail on the muscles of the eye.
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