nail dysplasia

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
Article Title: 

Dyskeratosis Congenita

Clinical Characteristics
Ocular Features: 

The conjunctiva and eyelids are prominently involved as part of the generalized mucocutaneous disease.  Keratinization of the lid margins, absent lacrimal puncta, trichiasis, cicatrizing conjunctivitis, entropion, ectropion, blepharitis, sparse eyelashes, and symblephara are important features.  The cornea is also involved with keratinization of the epithelial surface and vascularization.  The nasolacrimal duct is sometimes blocked.  At least one patient has been reported to have an exudative retinopathy. 

Systemic Features: 

Dyskeratosis congenita consists of a heterogeneous (genetic and clinical) group of inherited bone marrow failure and premature aging syndromes with the common feature of shortened telomeres.  There is considerable variability in the clinical features.  Prominent manifestations include nail dysplasia, oral leukoplakia, abnormal dentition, and reticulated skin pigmentation. Some patients have cognitive impairments.  Liver failure, testicular atrophy, pulmonary fibrosis, aplastic anemia, and osteoporosis along with features of aging such as premature grey hair and loss are typical.  There is an increased risk of malignancies, especially acute myelogenous leukemia.  Bone marrow failure is the major cause of early death.

Genetics

At least three autosomal dominant, three autosomal recessive, and one X-linked form of dyskeratosis congenita are recognized.  Mutations in at least 7 genes have been implicated.

Autosomal dominant disease can result from mutations in the TERC gene (DKCA1; 3q36.2; 127550), the TERT gene (DKCA2; 5p15.33; 613989), and the TINF2 gene (DKCA3; 14q12; 613990).  Mutations in the TINF2 gene are also responsible for Revesz syndrome (268130) with many features of DKC in addition to ocular findings of an exudative retinopathy resembling Coats disease.

Autosomal recessive disease is caused by mutations in the NOP10 (NOLA3) gene (DCKB1; 224230; 15q14-q15), the  NHP2 (NOLA2) gene (DKCB2; 5q35; 613987), and the WRAP53 gene (DKCB3; 17p13; 613988).  Mutations in the TERT gene may also cause autosomal recessive disease known as DKCB4 (613989).  

The X-linked disease (DKCX) (Zinsser-Engman-Cole syndrome) results from a mutation in the DKC1 gene (Xq28; 305000).  The same gene is mutated in Hoyeraal-Hreidarsson syndrome (300240) which some consider to be a more severe variant of dyskeratosis congenita with the added features of immunodeficiency, microcephaly, growth and mental retardation, and cerebellar hypoplasia. 

The majority of mutations occur in genes that provide instructions for making proteins involved in maintainence of telemeres located at the ends of chromosomes.  Shortened telomeres can result from maintainence deficiencies although the molecular mechanism(s) remain elusive.

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

Treatment for DKC with hematopoietic stem cell transplantation can be curative but its long-term efficacy is poor.  Some advocate androgen therapy first.  Lifelong cancer surveillance and frequent ocular and dental evaluations are important with specific treatment as indicated.

References
Article Title: 

Focal Dermal Hypoplasia

Clinical Characteristics
Ocular Features: 

Features have considerable heterogeneity and few patients have all of them.  Some ocular abnormalities are found in 40% of patients.  Microphthalmia is common and many patients (30%) have colobomas of the iris and choroid.  Some patients have dislocated lenses.  Distinctive peripheral corneal lesions consisting of discrete vascularized subepithelial opacities have been described.  Occasional patients have conjunctival or lid margin papillomas.  Strabismus and nystagmus are common.

Systemic Features: 

This disorder has a wide variety of clinical features and many occur in only a few patients.  The skin has focal areas of hypoplasia with hypopigmentation, often appearing in a streak or linear pattern.  These areas may be present at birth and contain bullae or urticarial lesions with signs of inflammation.  Telangiectases and herniated fat may appear in these areas.   Oral, esophageal, and laryngeal fibrovascular papillomas occur but they may also be seen in the perineal, vulvar, and perianal areas.  These may be large, friable, and recurrent.  The teeth erupt late and are usually hypoplastic.  The nails are often dysplastic and the hands and feet may be 'split' with syndactyly of the third and fourth fingers giving a 'lobster claw' appearance.  Polydactyly may be present.  Most have thin 'protruding' ears.  A variety of skeletal anomalies have been reported including absence of metatarsals and metacarpals.  A considerable number of patients have mild to moderate mental deficits.  Severely affected females may die in infancy.

Genetics

This is considered an X-linked dominant disorder with lethality in males.  However, numerous affected males (>30) and rare instances of father-to-daughter transmission have been reported and it has been suggested that half-chromatid mutations or postzygotic somatic mosaicism in these males might be responsible.  Mutations in the PORCN gene (Xp11.23) have been associated with FDH.

Pedigree: 
X-linked dominant, mother affected
Treatment
Treatment Options: 

Surgery may be required for the papillomas if they are obstructive.

References
Article Title: 

Sorsby Macular Coloboma Syndrome

Clinical Characteristics
Ocular Features: 

Macular colobomas, usually bilateral, are the major ocular feature of this oculoskeletal disorder.  These are non-progressive and are generally heavily pigmented.  Vision is, of course, severely reduced (20/200) and horizontal or pendular nystagmus is a feature in some cases.

Systemic Features: 

The systemic features are primarily skeletal.  Patients have short-limbed dwarfism and brachydactyly of the type B variety.  The thumbs and sometimes the large toes may be broad and bifid.  The distal two phalanges sometimes short, absent, or duplicated and the nails can be dysplastic or absent. Syndactyly of several digits in both hands and feet is common.  The ears are large and protuberant and some patients have deafness.  Oligodontia may be present.  Cartilage can have diastrophic changes.  Mental development is normal.

Genetics

In the few families reported, the transmission pattern is vertical suggesting autosomal dominant inheritance but no mutation or locus has been reported.  The mutation causing brachydactyly type B1 was not present in several cases.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Surgical treatment of digital anomalies can be beneficial.  Low vision aids could be helpful as well.

References
Article Title: 
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