Characterization of the c.190T>C missense mutation in BRCA1 codon 64 (Cys64Arg)

Area of Science:

• Genetics
• Oncology
• Molecular Biology

Background:

• A family in Milan, Italy, exhibited a high prevalence of ovarian and breast cancer across three generations.
• Five out of six family members were affected, with four diagnosed with ovarian lesions.

Purpose of the Study:

• To investigate the functional consequences of the identified BRCA1 c.190T>C mutation.
• To identify additional genetic polymorphisms that may contribute to the observed cancer phenotypes.

Main Methods:

• Molecular modeling to assess the impact of the Cys64Arg substitution on the BRCA1 protein structure.
• Splicing analysis to evaluate the mutation's effect on exon 5 splicing.
• Genotyping of BRCA1 and BRCA2 genes in the Italian family and a Polish family.

Main Results:

• The c.190T>C mutation in BRCA1 was found to disrupt the BRCA1-BARD1 interaction, crucial for tumor suppression.
• This mutation modulated exon 5 splicing, with an effect opposite to the c.190T>G transversion.
• Two polymorphisms, c.2612C>T in BRCA1 and c.-26G>A in BRCA2, were identified and associated with modified ovarian cancer risk in carriers of deleterious BRCA1 mutations.

Conclusions:

• The BRCA1 c.190T>C mutation has significant functional implications for tumor suppressor activity.
• The identified BRCA1 and BRCA2 polymorphisms may act as ovarian cancer risk modifiers.
• These findings contribute to understanding the genetic basis of hereditary breast and ovarian cancer syndromes.