Localization of a gene for Duane retraction syndrome to chromosome 2q31.

Duane retraction syndrome (DRS) is a congenital eye-movement disorder characterized by a failure of cranial nerve VI (the abducens nerve) to develop normally, resulting in restriction or absence of abduction, restricted adduction, and narrowing of the palpebral fissure and retraction of the globe on attempted adduction. DRS has a prevalence of approximately 0.1% in the general population and accounts for 5% of all strabismus cases. Undiagnosed DRS in children can lead to amblyopia, a permanent uncorrectable loss of vision. A large family with autosomal dominant DRS was examined and tested for genetic linkage. After exclusion of candidate regions previously associated with DRS, a genomewide search with highly polymorphic microsatellite markers was performed, and significant evidence for linkage was obtained at chromosome 2q31 (D2S2314 maximum LOD score 11.73 at maximum recombination fraction. 0). Haplotype analysis places the affected gene in a 17.8-cM region between the markers D2S2330 and D2S364. No recombinants were seen with markers between these two loci. The linked region contains the homeobox D gene cluster. Three of the genes within this cluster, known to participate in hindbrain development, were sequenced in affected and control individuals. Coding sequences for these genes were normal or had genetic alterations unlikely to be responsible for the DRS phenotype. Identifying the gene responsible for DRS may lead to an improved understanding of early cranial-nerve development.

Anatomic considerations in penetrating gluteal wounds.

A retrospective study of 81 patients with penetrating gluteal wounds was performed to determine if the site of penetration was useful in predicting the likelihood of associated vascular or visceral injury. There were 53 gunshot wounds and 28 stab wounds, including one impalement. The gluteal region was divided into upper and lower zones by determining whether entry occurred above or below the greater trochanters. Sixty-six percent of all penetrating gluteal wounds entered the upper zone. Thirty-two percent of patients with upper zone penetration had associated vascular or visceral injury. Only one of 27 patients with lower zone penetration sustained major injury. The site of entry plays a critical role in determining the likelihood of serious injury associated with penetrating gluteal wounds. Wounds penetrating above the greater trochanters demand thorough evaluation, especially gunshot wounds.