A new era for the dark genome.

Area of Science:

• Genetics
• Molecular Biology
• Ophthalmology

Background:

• Autosomal dominant retinitis pigmentosa (adRP) is a group of inherited retinal diseases.
• The genetic causes of many adRP cases remain unknown, particularly those involving noncoding regions of the genome.

Purpose of the Study:

• To identify novel genetic variants responsible for autosomal dominant retinitis pigmentosa.
• To investigate the role of noncoding small nuclear RNA (ncRNA) genes in retinal degeneration.

Main Methods:

• Whole-exome sequencing and segregation analysis in affected families.
• Functional studies to assess the impact of identified variants on ncRNA gene function.

Main Results:

• Variants in the noncoding small nuclear RNA genes RNU4-2 and four RNU6 paralogs were identified as a cause of adRP.
• Demonstrated pleiotropy for RNU4-2 variants, affecting both retinal structure and function.
• Expanded the known genetic basis of Mendelian diseases to include previously uncharacterized 'dark genome' regions.

Conclusions:

• Noncoding small nuclear RNA gene variants are a significant, previously unrecognized cause of autosomal dominant retinitis pigmentosa.
• RNU4-2 variants exhibit pleiotropy, contributing to a complex disease phenotype.
• This research broadens the scope of genetic factors implicated in inherited retinal diseases and highlights the importance of exploring noncoding genomic regions.