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| LETTER TO THE EDITOR |
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| Year : 2022 | Volume
: 4
| Issue : 1 | Page : 8 |
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How to make a differential diagnosis between choroideremia and retinitis pigmentosa
Ali Nouraeinejad
Department of Clinical Ophthalmology, Institute of Ophthalmology, University College London, London, United Kingdom
| Date of Submission | 16-Nov-2021 |
| Date of Acceptance | 25-Nov-2021 |
| Date of Web Publication | 09-Feb-2022 |
Correspondence Address:
Dr. Ali Nouraeinejad
Department of Clinical Ophthalmology, Institute of Ophthalmology, University College London, London, England
United Kingdom
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/pajo.pajo_120_21
How to cite this article:
Nouraeinejad A. How to make a differential diagnosis between choroideremia and retinitis pigmentosa. Pan Am J Ophthalmol 2022;4:8 |
How to cite this URL:
Nouraeinejad A. How to make a differential diagnosis between choroideremia and retinitis pigmentosa. Pan Am J Ophthalmol [serial online] 2022 [cited 2023 Sep 27];4:8. Available from: https://www.thepajo.org/text.asp?2022/4/1/8/337477 |
Dear Editor,
The term retinal dystrophy is used to describe a heterogeneous group of hereditary disorders in which the loss of photoreceptor function results in progressive visual impairment.[1] The most common example is retinitis pigmentosa.[1] One of the most important retinal dystrophies that may be confused with retinitis pigmentosa is choroideremia.[1] Retinitis pigmentosa has broadly gained attention globally, but choroideremia is less heard.[1]
Choroideremia is an X-linked recessive (XLR) inherited, bilateral progressive chorioretinal dystrophy/degeneration leading to blindness by late adulthood.[1],[2],[3],[4],[5],[6],[7] It is caused by mutations in the CHM gene which encodes Rab escort protein-1.[1],[2],[3],[4],[5],[6],[7] Choroideremia is evident as a progressive degenerative disorder of the photoreceptor layer, retinal pigment epithelium (RPE), and choroid.[1],[6],[8] Areas of RPE atrophy are noticed early in the mid-periphery and then developed centrally.[1] This is associated with the loss of photoreceptors and the choriocapillaris.[1]
Preliminary symptoms of patients with choroideremia often include gradual decline in central visual acuity, nyctalopia, and constriction of the peripheral visual field.[1] Nyctalopia is generally the first symptom often with onset during childhood.[1]
Since choroideremia has an XLR pattern, male patients predominantly show the typical aspects of early nyctalopia during the first decade of childhood that advance into severe peripheral vision loss followed by legal blindness in late adulthood around the fifth to sixth decades.[6],[7],[8],[9],[10] Nevertheless, although female carriers stay typically without symptoms, they can experience nyctalopia and show proof of pigmentary changes and chorioretinal degeneration in the fundus with coupled subnormal visual sensitivity.[6],[7],[8],[10],[11],[12],[13] However, the chorioretinal degeneration built in female carriers is not obvious until typically the third to fourth decade.[12]
X-linked inheritable retinal dystrophies exhibit a distinguishing family pedigree so that the course of the dystrophy differs between males and females.[1],[14] Choroideremia and X-linked retinitis pigmentosa are two of the most common X-linked inheritable retinal dystrophies.[14] They share a variety of common clinical manifestations, including the same family pedigree, nyctalopia, constriction of the visual field (tunnel vision), gradually reduced visual acuity, and retinal degeneration.[1],[14] For this reason, it can be occasionally difficult to make a differential diagnosis between choroideremia and retinitis pigmentosa, which may lead to diagnostic confusion, especially in the absence of a typical fundus appearance.[1],[14],[15] In this context, it is documented that about 6% of patients primarily diagnosed with retinitis pigmentosa in fact have choroideremia.[16]
The author proposes for clinicians to consider the key classic triad of findings in retinitis pigmentosa that includes a bone spicule pigment migration pattern in the peripheral retina, optic disc pallor, and retinal vessel narrowing as well as another probable sign of epiretinal membrane formation.[1],[6],[16],[17],[18],[19]
The degree of pigment migration into the retina that typifies retinitis pigmentosa is not seen in patients with choroideremia.[1] In this respect, bilateral mid-peripheral intraretinal perivascular “bone spicule” pigmentary alterations and RPE atrophy related to arteriolar narrowing are noted in retinitis pigmentosa.[1] In addition, a gradual rise in density of the pigment with anterior and posterior spread and a tessellated fundus appearance expands in patients with retinitis pigmentosa due to exposure to large choroidal vessels.[1]
Moreover, retinitis pigmentosa may appear as a sporadic (simplex) disorder or be inherited in an autosomal dominant, autosomal recessive, or XLR mode.[1] However, the mode of inheritance is only XLR in patients with choroideremia.[1] The CHM gene is the only gene discovered in patients with choroideremia,[1],[20] which can be proved by genetic analysis to counsel the family.[1]
Acknowledgments
The author would like to express his honest gratitude and high respect for the lifetime support of his father, Mohammad Nouraeinejad.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | |  |
| 1. | Nouraeinejad A. Differential Diagnosis in Optometry and Ophthalmology. 2 nd ed. Iran: Noruzi Publication; 2017.  |
| 2. | Katz BJ, Yang Z, Payne M, Lin Y, Zhao Y, Pearson E, et al. Fundus appearance of choroideremia using optical coherence tomograpy. Adv Exp Med Biol 2006;572:57-61. |
| 3. | Zinkernagel MS, MacLaren RE. Recent advances and future prospects in choroideremia. Clin Ophthalmol 2015;9:2195-200. |
| 4. | Freund PR, Sergeev YV, MacDonald IM. Analysis of a large choroideremia dataset does not suggest a preference for inclusion of certain genotypes in future trials of gene therapy. Mol Genet Genomic Med 2016;4:344-58. |
| 5. | Heon E, Alabduljalil T, McGuigan III DB, Cideciyan AV, Li S, Chen S, et al. Visual function and central retinal structure in choroideremia. Invest Ophthalmol Vis Sci 2016;57:T377-87. |
| 6. | Mitsios A, Dubis AM, Moosajee M. Choroideremia: From genetic and clinical phenotyping to gene therapy and future treatments. Ther Adv Ophthalmol 2018;10:1-18. |
| 7. | Dong S, Tsao N, Hou Q, Bozkaya D, Leroy BP. US health resource utilization and cost burden associated with choroideremia. Clin Ophthalmol 2021;15:3459-65. |
| 8. | Moosajee M, Ramsden SC, Black GC, Seabra MC, Webster AR. Clinical utility gene card for: Choroideremia. Eur J Hum Genet 2014;22::e1-e4. |
| 9. | Coussa RG, Kim J, Traboulsi EI. Choroideremia: Effect of age on visual acuity in patients and female carriers. Ophthalmic Genet 2012;33:66-73. |
| 10. | Pennesi ME, Birch DG, Duncan JL, Bennett J, Girach A. Choroideremia: Retinal degeneration with an unmet need. Retina 2019;39:2059-69. |
| 11. | Bonilha VL, Trzupek KM, Li Y, Francis PJ, Hollyfield JG, Rayborn ME, et al. Choroideremia: Analysis of the retina from a female symptomatic carrier. Ophthalmic Genet 2008;29:99-110. |
| 12. | Thobani A, Anastasakis A, Fishman GA. Microperimetry and OCT findings in female carriers of choroideremia. Ophthalmic Genet 2010;31:235-9. |
| 13. | Edwards TL, Groppe M, Jolly JK, Downes SM, MacLaren RE. Correlation of retinal structure and function in choroideremia carriers. Ophthalmology 2015;122:1274-6. |
| 14. | Yang J, Wang LN, Yu RG, Hu LY, Gong X, Chen L, et al. Multimodal imaging of the carriers of choroideremia and X-linked retinitis pigmentosa. Int J Ophthalmol 2018;11:1721-5. |
| 15. | Guo H, Li J, Gao F, Li J, Wu X, Liu Q. Whole-exome sequencing reveals a novel CHM gene mutation in a family with choroideremia initially diagnosed as retinitis pigmentosa. BMC Ophthalmol 2015;15:85. |
| 16. | MacDonald IM, Sereda C, McTaggart K, Mah D. Choroideremia gene testing. Expert Rev Mol Diagn 2004;4:478-84. |
| 17. | Lee TK, McTaggart KE, Sieving PA, Heckenlively JR, Levin AV, Greenberg J, et al. Clinical diagnoses that overlap with choroideremia. Can J Ophthalmol 2003;38:364-72. |
| 18. | Hartong DT, Berson EL, Dryja TP. Retinitis pigmentosa. Lancet 2006;368:1795-809. |
| 19. | Bowne SJ, Humphries MM, Sullivan LS, Kenna PF, Tam LC, Kiang AS, et al. A dominant mutation in RPE65 identified by whole-exome sequencing causes retinitis pigmentosa with choroidal involvement. Eur J Hum Genet 2011;19:1074-81. |
| 20. | van den Hurk JA, Schwartz M, van Bokhoven H, van de Pol TJ, Bogerd L, Pinckers AJ, et al. Molecular basis of choroideremia (CHM): Mutations involving the Rab escort protein-1 (REP-1) gene. Hum Mutat 1997;9:110-7. |
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