exudative retinopathy

Hoyeraal-Hreidarsson Syndrome

Clinical Characteristics
Ocular Features: 

Little is known about the ocular signs in this rare disorder.  As many patients have systemic features of dyskeratosis congenita, however, it is possible that some of the ocular findings such as conjunctival and corneal scarring and lid margin distortion might be similar.  Hoyeraal-Hreidarsson syndrome, though, is a more severe disease and many infants may die before the mucocutaneous manifestations appear.  At least one patient has had an exudative retinopathy similar to that seen in Revesz syndrome (268130).  Epiphora and a preretinal hemorrhage have also been reported.

Systemic Features: 

Features of pancytopenia usually appear after 5 months of age while growth retardation and microcephaly are evident soon after birth.  The marrow may show progression to myelodysplasia.  Birth weight is usually low.  Truncal ataxia and axial hypotonia have been reported and MRI imaging reveals cerebellar hypoplasia.  Global developmental delay is a common feature and a few patients have seizures.  Susceptibility to infection has been noted but the basis for an immunodeficiency remains elusive.  Some patients have signs of dyskeratosis congenita such as sparse hair, nail dysplasia, and a reticular pattern of skin pigmentation.

Genetics

This is an X-linked disorder resulting from mutations in the DKC1 gene (Xq28) active in telomere maintainence.  As expected, the vast majority of affected individuals are male but at least 3 females have been reported. The same gene is also mutated in the X-linked form of dyskeratosis congenita (305000) suggesting that the two are allelic or that both are the same disease.  There are clear clinical differences, however, as severe developmental delay, immunodeficiency, cerebellar hypoplasia, and microcephaly are generally not present in the latter disorder.

There is evidence for telomere length variations in this syndrome and in dyskeratosis congenita.  Homozygous mutations in RTEL1 (regulator of telomere length helicase 1) (20q13.33) have also been found in these conditions.

Pedigree: 
X-linked recessive, carrier mother
X-linked recessive, father affected
Treatment
Treatment Options: 

No effective treatment has been reported.

References
Article Title: 

Révész Syndrome

Clinical Characteristics
Ocular Features: 

This is likely a severe form of dyskeratosis congenita with an exudative retinopathy in addition to the usual lid deformities, corneal opacification, conjunctival scarring.  The exudates are often present in early childhood, and may be of sufficient volume to present as leukocoria mimicking a retrolental mass.  The exudates extend through nearly all layers of the retina and are said to resemble Coats retinopathy. Vitreous hemorrhage and opacification has also been reported.  Severe vision loss and blindness may occur depending on the degree of retinal and vitreous disease.

Systemic Features: 

Patients with Revesz syndrome have cerebral calcifications, and hypoplasia of the cerebellum in addition to mild signs of dyskeratosis congenita such as a reticulated skin pattern, nail dysplasia, and oral leukoplakia.  Ataxia is a prominent sign but is not present in all patients.  Bone marrow failure with pancytopenia and a high risk of malignancies, however, are serious problems.  Aplastic anemia and neutropenia may present in early childhood while other signs may not appear until late childhood.  Sparse hair, intrauterine growth retardation and low birth weight are also features.   

Few patients with Revesz syndrome have been reported and the clinical features have not been fully delineated.  It is important to note that there is a large amount of clinical variation among patients.

Genetics

Heterozygous mutations in the TINF2 gene (14q12) have been found in Revesz syndrome.  Mutations in the same gene have also been found in the autosomal dominant form of dyskeratosis congenita (613990) suggesting that the two disorders, if distinct, are allelic.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Bone marrow failure may respond favorably to hematopoietic stem cell transplantation, at least for some time. Lifelong medical monitoring is required for the systemic and ocular disease.

References
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