Four probands (2.04%) bore P/LP variants in causative genes of other diseases, including two with spinocerebellar ataxia type 2 (SCA2), one with Alzheimer’s disease (AD) (PSEN1 p.Leu282Arg), and one with Perry syndrome (DCTN1 p.Tyr78His). Here, DCTN1 is linked to early-onset autosomal dominant Alzheimer disease.