retinal cysts

Retinitis Pigmentosa 78

Clinical Characteristics
Ocular Features: 

Onset of visual complaints is in the third or fourth decades with night blindness and visual field defects.  These symptoms are progressive with the oldest of three reported patients having 20/1250 vision at 51 years of age.  Classic signs of retinitis pigmentosa are usually present including disc pallor, pigment clumping, peripheral field constriction, and attenuated retinal vessels.  Intraretinal cysts may be detected with optical coherence tomography.  The full-field ERG shows general photoreceptor dysfunction with the rods most severely involved while pattern ERGs shows variable macular involvement.

Systemic Features: 

No systemic disease has been detected in the three reported individuals.

Genetics

Three unrelated individuals have been reported with homozygous or compound heterozygous mutations in the ARHGEF18 gene (19p13.2).   Five different mutant alleles were found among these patients.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported but low vision aids might be helpful.

References
Article Title: 

Biallelic Mutation of ARHGEF18, Involved in the Determination of Epithelial Apicobasal Polarity, Causes Adult-Onset Retinal Degeneration

Arno G, Carss KJ, Hull S, Zihni C, Robson AG, Fiorentino A; UK Inherited Retinal Disease Consortium., Hardcastle AJ, Holder GE, Cheetham ME, Plagnol V; NIHR Bioresource - Rare Diseases Consortium., Moore AT, Raymond FL, Matter K, Balda MS, Webster AR. Biallelic Mutation of ARHGEF18, Involved in the Determination of Epithelial Apicobasal Polarity, Causes Adult-Onset Retinal Degeneration. Am J Hum Genet. 2017 Feb 2;100(2):334-342.

PubMed ID: 
28132693

Heimler Syndrome 2

Clinical Characteristics
Ocular Features: 

Several cases have been reported with macular dystrophy and 'salt-and-pepper' mottling of the RPE extending to the midperiphery with foveal sparing.  Autofluorescence with hyper- and hypo-autofluorescent dots has been observed in the mottled areas of the RPE.  Spectral domain OCT has shown loss of the inner/outer segment boundary with RPE thinning and multiple retinal cysts but the ERG does not show rod-cone dysfunction. Visual acuity and the ocular fundus were normal in one patient until the age of 29 years when her vision dropped to 20/200 in one eye and 20/40 in the other.

Systemic Features: 

Primary dentition may be normal but secondary teeth have enamel hypoplasia (amelogenesis imperfecta).  The nails have Beau lines (transverse ridges) and leukonychia (white spots).  Severe sensorineural hearing loss develops sometime in the first year or two of life and it may be unilateral. At least one patient was documented to have had normal audiological test results until the age of 3 years.

Psychomotor development is normal at least until sensory deprivation occurs.

Genetics

This is a rare syndrome of ectodermally derived tissue which results from compound heterozygous mutations in the PEX6 gene (6p21.1).  A pair of monozygotic twin girls with this syndrome has been reported.  Parents are phenotypically normal.  No instance of parent-to-child transmission has been noted and it seems likely that this is an autosomal recessive disorder.

Another form of Heimler syndrome (234580) but with compound heterozygous mutations in the PEX1 gene (7q21.2) has been reported.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

One patient has been treated with carbonic anhydrase inhibitors with apparent stabilization of vision.  Low vision aids and assistive hearing devices are likely of benefit for at least some patients.

References
Article Title: 

Spectrum of PEX1 and PEX6 variants in Heimler syndrome

Smith CE, Poulter JA, Levin AV, Capasso JE, Price S, Ben-Yosef T, Sharony R, Newman WG, Shore RC, Brookes SJ, Mighell AJ, Inglehearn CF. Spectrum of PEX1 and PEX6 variants in Heimler syndrome. Eur J Hum Genet. 2016 Nov;24(11):1565-1571.

PubMed ID: 
27302843

Macular dystrophy in Heimler syndrome

Lima LH, Barbazetto IA, Chen R, Yannuzzi LA, Tsang SH, Spaide RF. Macular dystrophy in Heimler syndrome. Ophthalmic Genet. 2011 Jun;32(2):97-100.

PubMed ID: 
21366429
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