Novel Mutations in the DYNC1 H1 Tail Domain Refine the Genetic and Clinical Spectrum of Dyneinopathies.

ABSTRACT The heavy chain 1 of cytoplasmic dynein ( DYNC1 H1) is responsible for movement of the motor complex along microtubules and recruitment of dynein components. Mutations in DYNC1H1 are associated with spinal muscular atrophy ( SMA), hereditary motor and sensory neuropathy ( HMSN), cortical malformations, or a combination of these. Combining linkage analysis and whole-exome sequencing, we identified a novel dominant defect in the DYNC1 H1 tail domain (c.1792 C> T, p. Arg598 Cys) causing axonal HMSN. Mutation analysis of the tail region in 355 patients identified a de novo mutation (c.791 G> T, p. Arg264 Leu) in an isolated SMA patient. Her phenotype was more severe than previously described, characterized by multiple congenital contractures and delayed motor milestones, without brain malformations. The mutations in DYNC1 H1 increase the interaction with its adaptor BICD2. This relates to previous studies on BICD2 mutations causing a highly similar phenotype. Our findings broaden the genetic heterogeneity and refine the clinical spectrum of DYNC1H1, and have implications for molecular diagnostics of motor neuron diseases. [ABSTRACT FROM AUTHOR]