Identification Of A Known Mutation In Notch3in Familiar CADASIL In China

Cerebral autosomal dominant arteriopathy with subcortical infarcts andleukoencephalopathy (CADASIL) is an inherited dominant cerebrovascular diseasewith attacking in adults, clinical features are characterized by recurrent ischemicstroke, vascular dementia and migraine with aura, there are mental disorders asdepression and even epilepsia in individual patients. The disease breaking out atpatients’ middle age, developing progressively, and the symptoms exsist in thepatients’ following lifetime, so seeking for the all causing genes and the pathogenicincentives is very important. Enriching and consummating the spectrum of thecausing genes could provide help for diagnosis of the disease,segregating from thepathogenic incentives,patients carried with the causing genes would prevent thedisease.Notch3gene located at human chromosome19was idetified as the causing genein1996, A large number of mutations in the23exons of the Notch3gene have beenreported to be associated with CADASIL, but the full spectrum of genetic changesleading to this disease is yet to be known.We sequenced members of a5-generational Han Chinese family with CADASILpatients with Sanger Sequencing in our study, seeking for more mutant bases to enrichthe spectrum of the causing genes.Methods:1、Checked the medical records of the5-generational Han Chinesefamily members, collected the clinical data;2、Using STR method to identify where the pathogenic gene located,we usedSTR D6S1014in our study. 3、Extracted genome DNA from the44family members and100contronlmembers, amplified the33exons of the N3gene, Sanger sequencing to find genealterations;4、Comparison of NOTCH3protein sequences from six mammalian species bymultiple-sequence alignment analysis.Results:1、The proband’s symptoms began at the age of47. The main clinicalmanifestations included mild dysarthria and left central facial and tongue paralysis.The MRI examination results showed long T1and long T2signals on the white matteraround the ventricles, and punctate long T1and long T2signals in the brainstem.2、The mutation was located in Notch3gene;3、Sanger sequencing of the amplified fragment of Notch3in all affectedindividuals identified a single base alteration,475C>T, in exon4of the Notch3gene,resulting in the substitution of Arg to Cys at codon133(Arg133Cys). The otherindividuals in this family did not carry this mutation, and the mutation was not presentin100normal controls.4、The133Arg residue was located in a highly conserved region of the protein.Conclusion: There was few reports about this mutation in N3, although a largenumber of reported cases coming from European Caucasian families, and5mutationcarriers who were not exposed to any vascular risk factors did not show symptoms,indicated that the penetrance was not complete and vascular risk factors may play avital role in the development of CADASIL.