Novel Mutations in PRPF31 Causing Retinitis Pigmentosa Identified Using Whole-Exome Sequencing

Area of Science:

• Genetics
• Ophthalmology
• Molecular Biology

Background:

• Retinitis pigmentosa (RP) is a group of inherited retinal diseases causing progressive vision loss.
• Genetic mutations are the primary cause of RP, necessitating the identification of disease-associated genes and variants.
• The pre-mRNA processing factor 31 (PRPF31) gene is known to be involved in RP pathogenesis.

Purpose of the Study:

• To identify disease-causing mutations in the PRPF31 gene in patients with retinitis pigmentosa.
• To investigate the functional consequences of identified PRPF31 mutations on protein expression and stability.

Main Methods:

• Whole-exome sequencing (WES) was performed on RP patients (families and sporadic cases).
• Green fluorescent protein (GFP)-tagged PRPF31 wild-type (WT) and variant expression vectors were constructed.
• HEK293 cells were used to assess protein expression, localization, and stability (using cycloheximide treatment).

Main Results:

• Three frameshift (c.547delG, c.804delG) and one stopgain (c.1060C>T) PRPF31 variants were found in RP families.
• Mutations c.547delG and c.804delG significantly reduced GFP-PRPF31 expression, while c.1060C>T increased it.
• The stopgain mutation (GFP-PRPF31sg) exhibited increased protein stability compared to WT.
• Novel mutations (c.G781C, c.A1373T, c.C1222T) were identified in sporadic RP patients.
• PRPF31 WT localized to the nucleus, whereas mutants were found in both nucleus and cytoplasm.

Conclusions:

• Novel PRPF31 mutations associated with retinitis pigmentosa were identified.
• Specific PRPF31 mutations impact gene expression levels.
• The stopgain PRPF31 mutation leads to increased protein stability, potentially contributing to RP pathogenesis.