Aberrant splicing of MAPT exon 2 is the first reported splicing abnormality in the DM1 brain and has been suggested to be involved in NFTs formation, which is often observed in the temporal and frontal cortices of patients with DM1.16,62 CLASP2 is suggested to play an important role in neuronal differentiation, although the biological significance of abnormal splicing of CLASP2 exon 23 is unknown.63 The aberrant splicing in DM1 cortical neurons detected in our study may be involved in the neuronal loss in the cerebral cortex reported in previous neuropathological studies. The gene discussed is MAPT; the disease is myotonic dystrophy type 1.