ZNF513

ZNF513 is thought to act as a transcription factor, a kind of protein that switches other genes on or off at the right time. In the retina, it appears to help control genes that build and maintain photoreceptors, the rod and cone cells that turn light into signals for the brain. Laboratory work found that the normal ZNF513 protein attaches to the control regions of several photoreceptor (definition: A light-sensing cell in the retina. Rods (used for night and peripheral vision) and cones (used for color and detail) are the two types.) genes, while a mutant version studied in the same experiments could not. This gene is also known by the aliases RP58 and ZFP513; under these aliases, two slightly different versions of its protein have been described.

Retinitis pigmentosa linked to ZNF513 involves the gradual loss of rod and then cone photoreceptors. In general, retinitis pigmentosa is characterized by night blindness, a slow narrowing of the field of vision, and eventual loss of central vision. These features were described as the clinical hallmarks of the condition in the family in which the ZNF513 link was first reported. Because only a few affected people have been described, the exact age of onset, speed of change, and severity cannot be predicted for any one person from the available evidence.

The connection between ZNF513 and retinitis pigmentosa was first established in a consanguineous Pakistani family, where affected members carried the same change in both copies of the gene, a single-letter substitution written as p.C339R. That study showed ZNF513 is active in the retina, including the photoreceptor (definition: A light-sensing cell in the retina. Rods (used for night and peripheral vision) and cones (used for color and detail) are the two types.) layers. To test the gene's role, researchers reduced its activity in zebrafish, which led to smaller eyes, a thinner retina, and loss of photoreceptors. Adding back the normal gene reversed these effects, but adding back the mutant version did not, supporting the idea that the change was responsible. A later study screening candidate genes across several families reported an additional ZNF513 variant, and in that instance the inheritance pattern appeared to be dominant rather than recessive.

The total number of people reported with ZNF513-related disease is very small, which limits how much can be said about the full picture. Most of the biological evidence comes from zebrafish and from cells grown in the laboratory rather than from large groups of patients. A 2018 report described a possible dominant inheritance pattern in a single family, which differs from the recessive pattern first established. Confirming an inheritance pattern generally requires finding more families with variants in the same gene. The authors of that candidate-gene study noted that worldwide data sharing is needed to find additional cases and provide stronger proof of which variants cause disease. How ZNF513 disease varies across different populations and families is not yet defined.

As of the date of this review, the supplied evidence does not identify an approved treatment aimed at ZNF513. Research so far has focused on understanding what the gene does and confirming that changes in it cause retinal disease. The zebrafish and cell experiments described are laboratory research into how the gene works, not treatments that are available to people.

• First identification of ZNF513 as a cause of recessive retinitis pigmentosa

  Human case study of one family combined with animal and laboratory experiments.

  What was found:

  They found a homozygous change (p.C339R) in ZNF513, showed the gene is active in photoreceptors, and demonstrated that reducing it in zebrafish harmed the retina while restoring the normal gene reversed the damage.

  Why it matters:

  This established ZNF513 as a gene in which changes can cause retinitis pigmentosa and pointed to its role in maintaining photoreceptors.

  Limitation: The human evidence rests on a single family, and much of the mechanism was shown in zebrafish and cells rather than in patients.

• Candidate-gene screening across families with inherited retinal disease

  Human genetic study across a small number of single families.

  What was found:

  They reported an additional ZNF513 variant and noted an apparently dominant inheritance pattern in that instance, while emphasizing that most retinal disease is caused by already-known genes.

  Why it matters:

  It adds a further human report for ZNF513 and raises the possibility that inheritance may not always be recessive.

  Limitation: Findings in isolated single families are hard to confirm, and the authors stressed that more cases and data sharing are needed to prove causation.

Inheritance for ZNF513 has been reported mainly as autosomal recessive (definition: An inheritance pattern where a person needs an altered copy of a gene from both parents to be affected. Parents with only one copy are usually unaffected carriers.), but one study described a possible dominant pattern, and a genetic counselor can explain what the confirmed pattern in your family means for relatives. Beyond this, the general caregiver guidance shown on every gene page applies here.

• Does my genetic report identify ZNF513 as the confirmed cause, and are both gene copies affected or only one?
• Given the reports of both recessive and dominant inheritance, what does my specific result mean for my relatives?
• What eye tests would help track how my retina is doing over time?
• Are there features of my vision that fit or differ from what has been reported for ZNF513?
• Would additional or updated genetic testing be worthwhile as more cases are described?
• How can I stay informed about research specific to ZNF513?

A confirmed genetic result can be reviewed with a retinal specialist and a genetic counselor to understand what it means for you. Genetic testing and counseling can also clarify the likely inheritance pattern in your family, which for ZNF513 has been reported as both recessive and, in one family, dominant. RP Hope's My Pathway tour can help you find resources that match where you are in the journey. Reading first-person accounts from others navigating an RP diagnosis may also help.