Adult-onset genetic leukoencephalopathies are increasingly recognized. They are heterogeneous groups of disorders that commonly have distinct pathologic mechanisms but they share the presence of supratentorial bilateral and symmetric white matter hyperintensities. Although these abnormalities are usually non-specific, some specific MRI findings exist and sometimes help to distinguish these disorders. In this review, our aim is to describe posterior fossa abnormalities seen in the main adult-onset genetic leukoencephalopathies enabling clinicians to perform oriented genetic/metabolic screening.