vitreous condensation

Axenfeld-Rieger Syndrome, Type 4

Clinical Characteristics
Ocular Features: 

The ocular features of this syndrome are similar to types 1-3 and primarily involve the anterior segment.  The iris stroma is hypoplastic and the pupil location may be eccentric.  Full thickness defects in the iris can lead to pseudopolycoria.   There may be anterior displacement of the angle structures with posterior embryotoxon and localized corneal opacification.    Glaucoma is a common feature and it may be present in early childhood, associated with tearing, a hazy cornea, and buphthalmos.  Vitreous condensation was noted in all 4 reported individuals.

Systemic Features: 

The midface is flat due to maxillary underdevelopment and the teeth may be abnormally small.  Micrognathia has been reported while the nasal root is abnormally broad.  The umbilical defect consists of redundant skin that failed to involute normally.  Congenital hip anomalies of undetermined nature and a hearing defect were reported in 2 of 4 individuals.

Genetics

Heterozygous mutations in the PRDM5 gene (4q25-q26) are responsible for this condition.  Mutations in CYP1b1, PITX2, and FOXC1 were not present.  One extended pedigree with 4 affected individuals from Pakistan has been reported. 

Type 1 Axenfeld-Rieger syndrome (180500) results from heterozygous mutations in PITX2, RIEG2 (601499) from heterozygous mutations in 13q14, and RIEG3 (602482) from heterozygous mutations in the FOXC1 gene.  Thus in three types of Axenfeld-Rieger syndrome (1,3, and 4) the responsible mutation occurs in a transcription factor gene which may explain why the phenotype is highly variable with considerable overlap in clinical signs.

Autosomal recessive brittle cornea syndrome type 2 (614170) is also caused by mutations in the PRDM5 gene. 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment is directed at correction of individual problems such as glaucoma and dental anomalies.  One patient required surgery for a retinal detachment. Lifelong ocular monitoring is recommended. 

References
Article Title: 

Retinitis Pigmentosa 72

Clinical Characteristics
Ocular Features: 

The history and fundus findings are typical for classic retinitis pigmentosa with onset of symptoms in the 4th and 5th decades or earlier. Salt and pepper pigmentation may also be present. These consist of night blindness, decreased visual acuity, and constriction of visual fields.  The fields are constricted to 10-30 degrees, and vision ranges from 20/25 to 20/40.  Optic pallor is often present, the retinal vessels are narrowed and bone-spicule pigmentation has been described.  Vitreous 'condensation' sufficient to obscure fundus details may be present.  ERG responses are absent or substantially reduced.  Heterozygotes have no symptoms or fundus abnormalities.

Systemic Features: 

No systemic features have been described.

Genetics

Homozygous mutations in the ZNF408 gene (11p11.2) are responsible for this condition.  The product of this gene is a transcription factor highly expressed in fetal and adult retina and plays a role in vasculogenesis.

Heterozygous mutations in the same gene cause familial exudative vitreoretinopathy (FEVR6) (616468) described in one family with significant vitreal and retinal vascular disease.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the basic disease.  Tinted lenses may provide some benefit.

References
Article Title: 

Whole-exome sequencing reveals ZNF408 as a new gene associated with autosomal recessive retinitis pigmentosa with vitreal alterations

Avila-Fernandez A, Perez-Carro R, Corton M, Lopez-Molina MI, Campello L, Garanto A, Fernandez-Sanchez L, Duijkers L, Lopez-Martinez MA, Riveiro-Alvarez R, Da Silva LR, Sanchez-Alcudia R, Martin-Garrido E, Reyes N, Garcia-Garcia F, Dopazo J, Garcia-Sandoval B, Collin RW, Cuenca N, Ayuso C. Whole-exome sequencing reveals ZNF408 as a new gene associated with autosomal recessive retinitis pigmentosa with vitreal alterations. Hum Mol Genet. 2015 Jul 15;24(14):4037-48.

PubMed ID: 
25882705
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