X-linked Retinitis Pigmentosa
Overview
X-linked retinitis pigmentosa (XLRP) is a severe, incurable genetic eye disease that causes progressive vision loss, primarily in males, leading to legal blindness by the mid-40s. Caused by mutations in the RPGR gene on the X chromosome, it results in the death of retinal cells and the degeneration of photoreceptors, starting with night blindness and progressing to tunnel vision. While there is no cure, gene therapy is a promising emerging treatment, and management focuses on low-vision aids, rehabilitation, and support.
Symptoms
Symptoms of X-linked retinitis pigmentosa (XLRP) include night blindness, progressive loss of peripheral (side) vision, leading to tunnel vision, and difficulty with color perception. Vision loss is gradual, typically starting in childhood, and may eventually affect central vision needed for detailed tasks. Some forms of XLRP also cause nystagmus (involuntary eye movements), short-sightedness (myopia), or strabismus (crossed eyes).
Causes
X-linked retinitis pigmentosa (XLRP) is caused by genetic mutations on the X chromosome, most commonly in the RPGR gene, and less often in RP2 or OFD1. These mutations lead to a progressive breakdown of light-sensitive photoreceptor cells in the retina, resulting in gradual vision loss, with males typically experiencing more severe and early-onset symptoms than females.
Prevention
There is currently no way to prevent X-linked retinitis pigmentosa (XLRP) because it is a genetic condition. However, you can take steps to maintain overall eye health, such as having regular eye exams and protecting your eyes from bright light. For those affected, current research focuses on gene therapies to slow or halt the progression of the disease, with some treatments already in clinical trials.
Diagnosis
X-linked retinitis pigmentosa (XLRP) is diagnosed through a combination of an eye exam, including a dilated eye exam, visual field testing, and retinal imaging, alongside electroretinography (ERG) and genetic testing to identify pathogenic mutations in genes like RPGR or RP2. Diagnosis can be challenging due to varied symptoms, but genetic analysis of family members and a comprehensive genetic panel or exome sequencing can confirm the X-linked pattern of inheritance and identify the specific genetic cause.
Prognosis
The prognosis for X-linked retinitis pigmentosa (XLRP) is generally poor, as it is a severe form of inherited vision loss that leads to progressive blindness, typically reaching legal blindness by age 45 in affected males. Symptoms, including night blindness and loss of peripheral vision, often begin in childhood. While there is currently no approved treatment, research is advancing in gene therapies that show promise in preclinical and clinical trials for potentially restoring vision.
Treatment
There are no approved treatments for X-linked retinitis pigmentosa (XLRP), but gene therapy using adenovirus-associated viruses (AAV) to deliver a functional copy of the RPGR gene shows promise in clinical trials and is an active area of research. Supportive care for vision loss is available, but the focus for potential restoration of vision is on gene therapy.