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Mutations in KRIT1 in familial cerebral cavernous malformations
J Zhang1, R E Clatterbuck, D Rigamonti
1Howard Hughes Medical Institute and The Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Neurosurgery
|May 12, 2000
Summary
A common KRIT1 gene mutation causes most cerebral cavernous malformations (CCM) in Hispanic-Americans, enabling early diagnosis. A new KRIT1 mutation was found in a Caucasian family, both leading to premature gene termination.
Area of Science:
- Genetics
- Molecular Biology
- Neurology
Background:
- Cerebral cavernous malformations (CCM) have a genetic basis, with mutations in the KRIT1 gene identified as a cause.
- Previous studies linked KRIT1 mutations to CCM in French and Hispanic-American families.
Purpose of the Study:
- To confirm the KRIT1 founder mutation in Hispanic-American families with CCM.
- To identify novel KRIT1 mutations in a Caucasian family with CCM.
- To analyze KRIT1 gene expression patterns.
Main Methods:
- Polymerase chain reaction (PCR) amplification of KRIT1 exons from genomic DNA.
- Single-strand conformation polymorphism (SSCP) analysis and DNA sequencing.
- Northern blotting to assess KRIT1 gene expression.
Main Results:
- A point mutation in KRIT1 exon 6, causing a premature termination codon, was confirmed in Hispanic-American families.
- An 11 base pair duplication in KRIT1 exon 7, leading to a premature termination codon, was identified in a Caucasian family.
- KRIT1 is widely expressed, with the highest levels detected in the brain.
Conclusions:
- The common KRIT1 mutation in Hispanic-Americans is confirmed, facilitating presymptomatic molecular diagnosis.
- Both identified mutations are predicted to trigger mRNA degradation via nonsense-mediated decay.
- Loss of function is the likely pathogenic mechanism for CCM caused by KRIT1 mutations.