DYNC1H1

MedlinePlus Genetics provides information about Charcot-Marie-Tooth disease

At least eight mutations in the DYNC1H1 gene have been found to cause a condition called spinal muscular atrophy with lower extremity predominance (SMA-LED). This condition is characterized by muscle weakness and wasting (atrophy) in the lower limbs that often begins in infancy or childhood. The DYNC1H1 gene mutations that cause SMA-LED replace single protein building blocks (amino acids) in the heavy chain subunit of the dynein complex. These changes alter the core of the dynein complex and impair its function. As a result, the movement of proteins, synaptic vesicles, and other materials within cells is reduced. Decreased synaptic vesicle transport in neurons that control muscle movement (motor neurons), leading to impaired neuronal growth, is thought to contribute to the muscle weakness and atrophy experienced by people with SMA-LED. It is unclear why this condition primarily affects the lower limbs.

DYNC1H1 gene mutations have been identified in some people who have intellectual disability. These affected individuals often have a brain malformation called polymicrogyria. Normally, the surface of the brain has many ridges or folds, called gyri. In people with polymicrogyria, the brain develops too many folds, and the folds are unusually small. In addition to intellectual disability, some affected individuals develop seizures and movement problems.

The DYNC1H1 gene mutations that cause intellectual disability are typically in a different region of the gene than those that cause SMA-LED (described above). It is unclear whether the site of the mutation is associated with the location in the body most affected by the disease, with SMA-LED-associated mutations primarily affecting motor neurons and intellectual disability-associated mutations primarily affecting neurons in the brain.