The TG6 isoform appears to be a specific marker for neurologic manifestations and recently it has been shown that neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and other polyglutamine diseases are characterized in part by aberrant cerebral transglutaminase activity and by increased cross-linked proteins in affected brains23. The gene discussed is TGM6; the disease is early-onset autosomal dominant Alzheimer disease.