Patterns of X-Linked Retinitis Pigmentosa Genetic Testing in England and Implications for Service Provision

Area of Science:

• Ophthalmology
• Genetics
• Public Health

Background:

• X-linked retinitis pigmentosa (XLRP) is a severe inherited retinal dystrophy.
• Mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene are the most common cause of XLRP.
• Understanding the prevalence of RPGR-XLRP is crucial for patient management and therapeutic development.

Purpose of the Study:

• To determine the prevalence of RPGR-associated XLRP in England.
• To investigate trends in genetic testing for XLRP over time.
• To assess equity of access to genetic testing across different regions and socioeconomic statuses.

Main Methods:

• A cross-sectional study utilizing data from English National Health Service patients referred for XLRP molecular testing (2004-2024).
• Calculation of mortality-adjusted prevalence rates per 100,000 population.
• Analysis of testing trends and equity by region and Index of Multiple Deprivation (IMD).

Main Results:

• The estimated mortality-adjusted prevalence of RPGR-XLRP in England is 1.67 per 100,000 population (2024), with an estimated 977 living patients.
• Prevalence was higher in males (2.18/100,000) than females (1.17/100,000).
• Testing rates were consistent across regions and socioeconomic quintiles, with a noted decrease in testing post-2019.

Conclusions:

• RPGR-XLRP affects a significant population in England, with a prevalence higher than other treatable inherited retinal dystrophies.
• No systematic inequities in genetic testing access were identified based on socioeconomic status or region.
• A decline in testing rates since 2020 requires further investigation for potential impacts on diagnosis and care.