Tisiana Low, Anastassios Kostakis, Meena Balasubramanian | Ophthalmic Genetics | Nov 7 2017 | Vol 39, Issue 2 | pgs. 286-287 | doi/full/10.1080/13816810.2017.1393827
Introduction
Retinitis pigmentosa (RP) refers to a group of inherited disorders that affect the retina’s ability to respond to light, leading to progressive visual loss. Retinitis pigmentosa sine pigmento is a variant of RP in which there is an absence of characteristic peripheral bone-spicule like pigmentary changes.
One of the genes found to be responsible for RP is IFT140, a ciliary transporter gene (OMIM *614620). Homozygous and compound heterozygous IFT140 variants have commonly been reported in Mainzer-Saldino syndrome and Jeune syndrome(1). However, in recent literature, non-syndromic IFT140-related RP have been reported. IFT140 encodes a sub-unit of intraflagellar transport complex A (IFTA), which is involved in retrograde ciliary transport(2).
It was previously referred to as KIAA0590 and located on chromosome 16p13.3. It is highly expressed in kidneys with moderate expression in ovary, testis, lung, prostate. Schmidts et al., 2013 demonstrated high expression of Ift140 in renal and retinal tissue in mouse embryos(3).
Although the phenotype associated with IFT140 variants is still emerging, it appears to encompass a variable spectrum ranging from non-syndromic, isolated RP (as demonstrated in this clinical report) to Short-rib thoracic dysplasia 9 with or without polydactyly (SRTD9; OMIM # 266920).
Case Report
We present a case of a 22-year-old female who attended her opticians for a frequent headaches review. It was found that her visual fields were restricted, with a slightly abnormal retina with greying and mottling (Fig 1). However, night-time vision was not reduced. An optical coherence tomography suggested likely RP, and electrodiagnostic testing confirmed the diagnosis. She was the first child of healthy, non-consanguineous, White European parents and had a younger sister who was fit and well with no family history of RP. A recent ophthalmology follow-up review found that the patient had visual acuities of 6/6 with patchy visual defects in bilateral eyes, but no significant decrease in visual fields.
References
Bifari IN, Elkhamary SM, Bolz HJ, et al. The ophthalmic phenotype of IFT140- related ciliopathy ranges from isolated to syndromic congenital retinal dystrophy. Br J Ophthalmology. 2015; 0:1-5.
Perrault I, Saunier S, Hanein S, et al. Mainzer-Saldino Syndrome Is a Ciliopathy Caused by IFT140 Mutations. Am J Hum Genet. 2012; 90(5):864–870.
Schmidts M, Frank V, Eisenberger T, et al. Combined NGS Approaches Identify Mutations in the Intraflagellar Transport Gene IFT140 in Skeletal Ciliopathies with Early Progressive Kidney Disease. Hum Mutat. 2013; 34(5):714–724.
Hull S, Owen N, Islam F, et al. Nonsyndromic retinal dystrophy due to bi-allelic mutations in the ciliary transport gene IFT140. Invest Ophthalmol Vis Sci. 2016; 57:1053–1062.
Neveling K, Collin R, Gilissen C, et al. Next-generation genetic testing for retinitis pigmentosa. Hum Mutat. 2012; 33(6):963-972.
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