Duane-Radial Ray syndrome (DRRS) is characterized by the Duane eye anomaly and radial ray malformations of the limbs. The Duane anomaly is a congenital disorder of eye movement defined by the limited or absent ability to move the eye outward (abduction) and/or inward (adduction). Radial ray malformations observed in this syndrome can include triphalangeal thumbs, preaxial polydactyly, hypoplasia/aplasia of the thumbs, hypoplasia/aplasia of the radii, and shortening and radial deviation of the forearms.
Acro-Renal-Ocular syndrome (AROS), which is allelic to DRRS, presents with radial ray malformations and Duane anomaly, along with other features such as ocular coloboma and renal abnormalities (renal hypoplasia, horseshoe kidney, vesico-utereral reflux, bladder diverticular, ectopia, and mild malrotation).
The overlap between DRRS and AROS is appreciable, and each syndrome has a highly variable intra- and interfamilial clinical phenotype. Other less common features belonging to both syndromes include hearing loss, ear malformations, epicanthal folds and very rarely, heart defects (atrial and ventricular septal defects).
The limb anomalies characteristic of DRRS/AROS overlap with two other clinically defined genetic syndromes: HoltOram syndrome (HOS), which is due to mutations in the TBX5 gene, and Townes-Brocks syndrome (TBS), caused by mutations in the SALL1 gene. Both DRRS/AROS and HOS are associated with upper limb malformations, hypoplasia/aplasia of the thumbs, and triphalanageal thumbs. Shared limb abnormalities observed in DRRS/AROS and TBS include preaxial polydactyl and triphalangeal thumbs. Genetic testing for all three disorders is available at GeneDx.