As we have discussed previously, abnormal cortical activity accompanies the mirror movements in CMMD (19, 20).
Two brothers (aged, 29 and 30 years) exhibiting familial CMMD on the distal upper limbs were studied in task-based fMRI scans (see Supplementary Fig.
Severity of CMMD was rated by Wood-Teuber scale (0, no mirror movement; 1, hardly perceivable with repetitive mirror movement; 2, barely discernible with sustained mirror movement or obvious with brief-periodic mirror movements; 3, obvious and sustained repetitive mirror movement; 4, strong mirror movement activity in unintended side).
We investigated task-related activity within the components of the motor system of CMMD patients with RAD51 mutation.
Thus, abnormally uncrossed corticospinal fibers could be a contributing mechanism to CMMD with RAD51 mutation.
However, in CMMD patients there is an abnormally increased activity in M1 that is ipsilateral to the side of the intended voluntary movement, leading to a bilateral activation pattern in M1s (19, 20).
Our results show that activity of thalamus, a subcortical structure, was also abnormal in the CMMD patients.
Functional and structural connectivity analyses between the components of the motor loop in CMMD with larger patient population may provide further information.
In conclusion, we have found widespread functional abnormalities in brain structures of the motor loop in CMMD patients with RAD51 mutation.
* Congenital mirror movement disorders (CMMD) are closely related to abnormal primary motor cortex and supplementary motor area activity during unimanual movements.
* Increased bilateral activity is present in CMMD patients in thalamus, striatum, and globus pallidus during unimanual movements.