nerve fiber layer thinning

Optic Atrophy 9

Clinical Characteristics
Ocular Features: 

Two brothers have been reported with optic atrophy discovered as early as 3 and 5 years of age.  Visual acuity in the 3rd decade of life was in the 20/200 range which was stable into the 4th and 5th decades. They also had red-green dyschromatopsia and thinning of the nerve fiber layer most pronounced in the temporal areas of the retina corresponding to the location of most marked pallor seen in the optic nerve.  The nasal nerve fiber layer seemed to be preserved.  Paracentral scotomas could be demonstrated. 

Systemic Features: 

There were no systemic abnormalities reported in the brothers. 

Genetics

OPA9 is caused by homozygous or compound heterozygous mutations in the ACO2 gene (22q13.2).   

Mutations in ACO2 also cause infantile cerebellar retinal degeneration (ICRD) (614559) in which optic atrophy is a prominent feature associated with retinal degeneration, extensive neurodegenerative disease, and mitral valve dysfunction.  The mode of inheritance is autosomal recessive.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been described.

References
Article Title: 

Mutations in the tricarboxylic acid cycle enzyme, aconitase 2, cause either isolated or syndromic optic neuropathy with encephalopathy and cerebellar atrophy

Metodiev MD, Gerber S, Hubert L, Delahodde A, Chretien D, Gerard X, Amati-Bonneau P, Giacomotto MC, Boddaert N, Kaminska A, Desguerre I, Amiel J, Rio M, Kaplan J, Munnich A, Rotig A, Rozet JM, Besmond C. Mutations in the tricarboxylic acid cycle enzyme, aconitase 2, cause either isolated or syndromic optic neuropathy with encephalopathy and cerebellar atrophy. J Med Genet. 2014 Dec;51(12):834-8.

PubMed ID: 
25351951

Duane-Radial Ray Syndrome

Clinical Characteristics
Ocular Features: 

Most individuals have features of Duane’s anomaly, sometimes unilaterally.  Optic pallor with poor vision has been described in well-studied patients who also had thinning of the retinal nerve fiber layer.  The optic disk may appear hypoplastic.  Visual evoked potentials and pattern ERG amplitudes are decreased.

Other less common ocular features are microcornea, microphthalmia, ophthalmoplegia, hypertelorism, cataracts, epicanthal folds, colobomas, and chorioretinal scars.

Systemic Features: 

The systemic features are inconsistent (variable expressivity) with most patients having some variation of hypodactyly, polydactyly, syndactyly, and malformation of the hands.  The thumb is the most common digit involved and this is often associated with thenar hypoplasia.  Other skeletal features of the radial ray syndrome including absence of the radial and ulnar bones are variably present.  Hearing loss is described as sensorineural in etiology but malformations of the pinnae and external meatus are sometimes present.

Kidney anomalies include horseshoe malformations, abnormal rotation, ectopia, small size, vesicoureteric reflux, and pelvicalyceal dilatation.

Genetics

This is an autosomal dominant disorder due to heterozygous mutations in the SALL4 gene (20q13.2).

This syndrome is sometimes confused with the Holt-Oram syndrome but the latter is the result of mutations in a different gene and lacks ocular and renal abnormalities.  Duane syndrome 1 and 2 may also occur as isolated conditions.

The considerable clinical heterogeneity has led to alternate titles for this syndrome. For example, what is sometimes called the IVIC syndrome (147750) with similar features is also caused by mutations in this gene.  Duane-radial ray syndrome has also been called Okihiro syndrome. 

 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment is symptomatic in most cases although reconstructive surgery may be helpful for severe hand deformities.  Low vision aids may be beneficial.  

References
Article Title: 
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