Repeat Expansion and Somatic Instability in TCF4 in Patients With Fuchs Endothelial Corneal Dystrophy Identified by...

Area of Science:

• Genetics
• Ophthalmology
• Molecular Biology

Background:

• Fuchs' endothelial corneal dystrophy (FECD) is a degenerative eye disease.
• Trinucleotide repeat (TNR) expansions in genes like TCF4 are implicated in various genetic disorders.
• Understanding TNR instability in FECD is crucial for disease mechanism insights.

Purpose of the Study:

• To investigate TNR expansion and somatic repeat instability in the TCF4 gene in FECD patients.
• To utilize small pool polymerase chain reaction (SP-PCR) for precise analysis of repeat dynamics.
• To compare TNR expansion in corneal endothelium versus leukocyte DNA.

Main Methods:

• Selected 15 FECD patients with abnormal TCF4 CTG repeat expansion (>50 repeats).
• Employed SP-PCR to analyze repeat number and variation in leukocyte DNA.
• Collected corneal endothelium DNA from one patient for comparative SP-PCR analysis.

Main Results:

• Observed significant TNR expansion in TCF4 (average max repeat 1602 ± 1258).
• Demonstrated somatic repeat instability (average variation 19 ± 15), correlating with repeat number (R=0.84, P<0.05).
• Found higher CTG repeat numbers in corneal endothelium compared to leukocytes.

Conclusions:

• Somatic repeat instability in leukocytes correlates with TCF4 TNR expansion in FECD.
• Genomic DNA in corneal endothelium shows greater TNR expansion than in leukocytes of FECD patients.
• These findings highlight the role of TCF4 repeat instability in FECD pathogenesis.