Brain MRI findings in paediatric genetic disorders associated with white matter abnormalities

Genetic white matter disorders (GWMDs) consist of a large and heterogeneous group of diseases affecting the white matter (WM) of the central nervous system. Brain magnetic resonance imaging (MRI) is an important diagnostic tool for these diseases, since it is highly sensitive in detecting WM abnormalities within brain tissue. GWMDs often present unique signal abnormality patterns in brain MRI leading to correct diagnosis. Several specific imaging patterns have been discovered and reported to improve radiological diagnostics among these rare diseases. When GWMDs are suspected, careful brain MRI interpretation may guide further investigation methods such as exome or genome sequencing to establish correct diagnosis.

The aim of this study was to describe specific brain MRI patterns of these rare diseases in a distinct population of Northern Finland. The study was conducted at Oulu University Hospital in Northern Finland, and it included all paediatric patients with MRI data diagnosed with a known GWMD or genetic disorder associated with brain WM signal abnormalities in this tertiary care centre from 1990 to 2019. In the final analysis, 83 patients with genetically confirmed diagnoses were included in the cohort and the brain MRIs of the patients were interpreted. A total of 52 different GWMDs were encountered, and their brain imaging findings were reported.

Based on the radiological analysis and imaging patterns we provided an updated tool for radiologists to analyse brain MRIs of genetic disorders. We also found that delayed myelination and permanent hypomyelination were uncommon in genetic brain disorders. Our cohort also included a few recently described GWMDs and their imaging patterns were reported and illustrated.