Possible pathogenic variants were confirmed by performing Sanger sequencing with an ABI 3500XL DX Genetic Analyzer (Applied Biosystems, Foster City, CA, USA) following the procedure described in our previous study.20 (link) A co-segregation analysis was performed for all available familial members. The APOE genotypes were determined by multiplex amplification refractory mutation system PCR according as previously described.20 (link)