Clinical features of VRK1-associated disease can be divided into two categories: 1) clinical features of motor neuron disease 2) clinical features of brain involvement.
1) Motor neuron disease– results in muscle weakness and muscle wasting. In more severe cases, this can appear in early childhood, and in other cases weakness appears only in adolescence or early adulthood.
Weakness often begins in the lower extremities, progressing from the feet to the upper legs. This leads to progressive difficulties in walking. The upper extremities may also become weak over time.
Muscle wasting may become visible over time. In some cases there is also sensory nerve involvement, which can lead to numbness and lack of touch sensation.
2) Brain involvement– does not occur with the majority of mutations. If present, it is usually apparent at birth as small head (microcephaly). Brain imaging may show additional abnormalities in the brain structure. Involvement of the brain often leads to developmental delays, of motor milestones, language etc.
VRK1