PSEN1 Compound Heterozygous Mutations Associated with Cerebral Amyloid Angiopathy and Cognitive Decline Phenotype

Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder caused by the deposition of amyloid beta‐peptide (Aβ) aggregates. Aβ aggregates lead to vessel rupture and intracerebral hemorrhages, detected by magnetic resonance imaging (MRI). Presenile CAA is usually genetically determined by mutations in the amyloid precursor protein (APP) gene. However, mutations after codon 200 in the presenilin 1 (PSEN1) gene have been reported to facilitate CAA onset. Here, we analyzed the genetic bases in a patient of 55 years old affected by CAA and cognitive decline. DNA was isolated and genetic analysis was performed by Next‐Generation Sequencing (NGS). RNA was extracted and retro‐transcribed to perform segregation analysis by TOPO‐TA cloning. WB analysis was carried out to check the impact of the mutations on protein. Two compound heterozygous mutations in PSEN1 exon 10, such as a novel stop‐gain mutation (c.1070C > G) and a pathogenic splice variant (c.1129A > T), were found by NGS. Both mutations altered the presenilin 1 protein, truncating its C‐terminal portion. This is the first case of CAA and cognitive decline caused by two compound mutations in PSEN1. With this report, we suggest extending the genetic analysis to PSEN1 when cerebral microbleeds are observed by MRI investigation in a patient affected by presenile cognitive decline.