Insertion of GCGG between 4:273692 and 4:273693 and nucleotide changes A 273689 to G and A 273690 to T resulting in the addition of RAEVGFPSSWKTQKRHYTRKSRGFCAIYNREKKINLCSLKPRSKGKNETN after lysine 86 of all NfI isoforms and premature truncation after these novel amino acids.