Small in-frame deletions and missense mutations in CADASIL: 3D models predict misfolding of Notch3 EGF-like repeat...

Area of Science:

• Genetics
• Neurology
• Molecular Biology

Background:

• Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary microangiopathy leading to early-onset stroke.
• The Notch3 gene, encoding a transmembrane receptor with epidermal growth factor-like (EGF) domains, has been identified as the causative gene for CADASIL.

Purpose of the Study:

• To screen CADASIL families for mutations in the Notch3 gene, specifically in exons encoding the initial EGF-like repeats.
• To investigate the types of mutations and their impact on cysteine residues within Notch3 EGF-like domains.
• To model the potential structural consequences of identified mutations on Notch3 protein function.

Main Methods:

• Screening of 71 unrelated CADASIL families for mutations in two specific exons of the Notch3 gene.
• Mutation analysis including missense mutations and in-frame deletions.
• Generation of 3D homology models for Notch3 EGF domains to predict structural effects.

Main Results:

• Mutations in the Notch3 gene were identified in 70% of the studied CADASIL families.
• The majority of mutations (96%) were missense, with a few in-frame deletions observed.
• All identified mutations resulted in the gain or loss of a cysteine residue, suggesting a critical role for cysteine balance in Notch3 function.
• CpG dinucleotides were implicated as hotspots for recurrent mutations.

Conclusions:

• Mutations in the Notch3 gene, particularly those affecting cysteine residues in EGF-like domains, are a primary cause of CADASIL.
• The findings highlight the importance of cysteine residue integrity in Notch3 for preventing CADASIL pathogenesis.
• Predicted domain misfolding suggests a mechanism by which Notch3 mutations lead to this hereditary stroke disorder.