Neuronal and glial intranuclear inclusions in a patient with oculopharyngodistal myopathy associated with noncoding GGC repeat expansions in GIPC1.

Noncoding GGC repeat expansion of various genes leads to oculopharyngodistal myopathy (OPDM), an adult-onset progressive neuromuscular disorder characterized by ophthalmoplegia, pharyngeal dysfunction, and distal limb muscular weakness. Recently, clinical overlap among noncoding GGC repeat-associated neuromuscular diseases, including OPDM, fragile X-associated tremor/ataxia syndrome (FXTAS), and neuronal intranuclear inclusion disease (NIID), has been recognized. Here, we present an autopsy case of OPDM with GIPC1 mutation (OPDM2) in a 56-year-old man. Histopathological studies revealed loss of myelinated fibers in the cerebrum and the presence of neuronal and glial intranuclear inclusions, which are commonly observed in FXTAS and NIID. Numerous intranuclear inclusions in oligodendrocytes were a characteristic feature of our autopsied case. Although GGC repeat expansions in distinct genes produce similar neuropathological findings, such as neuronal and glial intranuclear inclusions, the affected cell populations differ.