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Removal of an Internal Translational Start Site from mRNA While Retaining Expression of the Full-Length Protein
Published on: March 16, 2022
The silent mutation MLH1 c.543C>T resulting in aberrant splicing can cause Lynch syndrome: a case report
Tatsuro Yamaguchi1,2, Tomokazu Wakatsuki3, Mari Kikuchi3
1Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital.
Abstract:
The proband was a 67-year-old man with transverse and sigmoid colon cancer. Microsatellite instability analysis revealed a high frequency of microsatellite instability, and immunohistochemical staining showed the absence of both MLH1 and PMS2 proteins in the sigmoid colon cancer tissue specimens from the patient. DNA sequencing revealed a nucleotide substitution c.543C>T in MLH1, but this variant did not substitute an amino acid. The MLH1 c.543C>T variant was located 3 bases upstream from the end of exon 6 and created a new splice donor site 4 bases upstream from the end of exon 6. Consequently, the last 4 bases of exon 6 were deleted and frameshift occurred. Thus, the MLH1 c.543C>T silent mutation is considered 'pathogenic'.
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