Retinal Dystrophy with or without Macular Staphyloma

Clinical Characteristics
Ocular Features: 

Few patients have had complete eye studies and physical findings are seemingly limited to the eye.  Patients complain of progressively decreasing vision as early as the first decade of life.  Abnormal retinal findings may be present by the second decade and maybe earlier.  The RPE can appear mottled and the retinal vessels are attenuated.  Retinal pigment clumping occurs later.  Night blindness and visual field constriction occur.  Cone and flicker ERGs may be nonrecordable while rod and flash ERGs are reduced consistent with a rod-cone dystrophy.  The retinal lamination has been described as abnormal on OCT in some individuals.

Macular staphylomas have been described in three unrelated offspring of consanguineous parents.

Vision loss is severe with legal blindness by midlife and one patient lost light perception by 40 years of age.  

Systemic Features: 

No consistent systemic abnormalities have been reported.

Genetics

Homozygous or compound heterozygous mutations in the C21orf2 gene (21q22.3) are the cause of this autosomal recessive syndrome.

Homozygous or heterozygous mutations in the same gene are responsible for axial spondylometaphyseal dysplasia (602271).

Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

References

Suga A, Mizota A, Kato M, Kuniyoshi K, Yoshitake K, Sultan W, Yamazaki M, Shimomura Y, Ikeo K, Tsunoda K, Iwata T. Identification of Novel Mutations in the LRR-Cap Domain of C21orf2 in Japanese Patients With Retinitis Pigmentosa and Cone-Rod Dystrophy. Invest Ophthalmol Vis Sci. 2016 Aug 1;57(10):4255-63.

PubMedID: 27548899

Khan AO, Eisenberger T, Nagel-Wolfrum K, Wolfrum U, Bolz HJ. C21orf2 is mutated in recessive early-onset retinal dystrophy with macular staphyloma and encodes a protein that localises to the photoreceptor primary cilium. Br J Ophthalmol. 2015 Dec;99(12):1725-31.

PubMedID: 26294103