Probable novel PSEN1 Gln222Leu mutation in a Chinese family with early-onset Alzheimer's disease.

Background: The rate of occurrence of Alzheimer's disease is increasing around the world. However, there is still no significant breakthrough in the study of its etiology and pathogenesis. Objective: To screen Alzheimer's disease pathogenic genes, which may be conducive to the elucidation of the pathogenic mechanisms of Alzheimer's disease And predict the pathogenicity by various computer software. Method: Clinical and neuroimaging examination, Whole Exome Sequencing, and Sanger sequencing were performed in the proband. Mutation sites were verified in 158 subjects. Results: We reported a proband carrying a probably novel pathogenic mutation, which clinically manifests as progressive memory loss, visual-spatial disorders, apraxia, psychobehavioral disorders, and temperamental and personality changes. Whole Exome Sequencing detected a novel missense mutation at codon 222 (Q222L), which is a heterozygous A to T point mutation at position 665 (c.665A>T) in exon 5 of the presenilin 1 leading to a glutamine-to-leucine substitution. The mutation was also identified by Sanger sequencing in one family member; nevertheless, it was not detected in the other 7 unaffected family members, 50 sporadic Alzheimer's disease patients and 100 control subjects. Conclusion: A novel mutation in exon 5 of the presenilin 1 gene (Gln222Leu) in a Chinese family with early-onset Alzheimer's disease has been reported, besides, it was predicted that the missense mutation was probably a novel pathogenic mutation that was reported for the first time in a Chinese family with early-onset Alzheimer's disease.