The first reported case of a deletion of the entire RPGR gene in a family with X-linked retinitis pigmentosa

Novel hemizygous single-nucleotide duplication in RPGR in a patient with retinal dystrophy and sensorineural hearing loss

BACKGROUND

The RPGR gene has been associated with X-linked cone-rod dystrophy. This report describes a variant in RPGR detected with exome sequencing (ES). Genes like RPGR have not always been included in panel-based testing and thus genome-wide tests such as ES may be required for accurate diagnosis.

METHODS

The Texome Project is studying the impact of ES in medically underserved patients who are in need of genomic testing to guide diagnosis and medical management. The hypothesis is that ES could uncover diagnoses not made by standard medical care.

RESULTS

A 58-year-old male presented with retinitis pigmentosa, sensorineural hearing loss, and a family history of retinal diseases. A previous targeted gene panel for retinal disorders had not identified a molecular cause. ES through the Texome Project identified a novel, hemizygous variant in RPGR (NM_000328.3: c.1302dup, p.L435Sfs*18) that explained the ocular phenotype.

CONCLUSIONS

Continued genetics evaluation can help to end diagnostic odysseys of patients. Careful consideration of genes represented when utilizing gene panels is crucial to ensure an accurate diagnosis. Medically underserved populations are less likely to receive comprehensive genetic testing in their diagnostic workup. Our report is an example of the medical impact of genomic medicine implementation.

X-Linked Retinitis Pigmentosa Gene Therapy: Preclinical Aspects

The most common inherited eye disease is retinitis pigmentosa (RP). X-linked RP (XLRP) is one of the most severe types of RP, with a considerable disease burden. Patients with XLRP experience a decrease in their vision and become blind in their 4th decade of life, causing much morbidity after starting a rather normal life. Treatment of XLRP remains challenging, and current treatments are not effective enough in restoring vision. Gene therapy of XLRP, capable of restoring the functional RPGR gene, showed promising results in preclinical studies and clinical trials; however, to date, no approved product has entered the market. The development of a gene therapy product needs through preliminary assessment of the drug in animal models before administration to humans. In this article, we reviewed the genetic pathology of XLRP, along with the preclinical aspects of the XLRP gene therapy, animal models, associated assessments, and future challenges and directions.