dental dysplasia

Oculodentodigital Dysplasia

Clinical Characteristics
Ocular Features: 

The eyes have been reported as small and sometimes appear deep-set.  The epicanthal folds are prominent and the lid fissures are small.  Microcornea and evidence of anterior chamber dysplasia including posterior synechiae, anterior displacement of Schwalbe’s line, and stromal hypoplasia in the peripupillary area may be present.  Many eyes have some persistence of the pupillary membrane. Nystagmus and strabismus has been seen in some individuals.  A few patients have evidence of a persistent hyperplastic primary vitreous, even bilaterally. Cataracts may be present as well and a few patients have been reported with open angle glaucoma.  Most patients have normal or near normal visual acuity.

Systemic Features: 

The clinical features of this syndrome are highly variable.  Hair is sparse and the nails are usually dysplastic.  The nose appears small and peaked with underdevelopment of the nasal alae, and the mandible may be broad.  The cranial bones are often hyperostotic and the long bones as well as the ribs and clavicle are widened.  The middle phalanges of the digits are usually hypoplastic or may be absent.  Syndactyly of fingers and toes is often a feature and camptodactyly is common.  The teeth are small and carious with evidence of enamel dysplasia.   Hair often grows slowly and is sparse.  A variety of neurological deficits have been reported but no consistent pattern has been recognized.  However, white matter lesions and basal ganglia changes have been documented on MRI.

Genetics

Both autosomal recessive and autosomal dominant inheritance have been proposed but in both cases the mutations are in the same gene, GJA1, located at 6q21-q23.2.

This disorder is allelic to Hallermann-Streiff syndrome (234100).

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No treatment for the general condition is available.  Cataracts and glaucoma require attention when present, of course.

References
Article Title: 

Tuberous Sclerosis 2

Clinical Characteristics
Ocular Features: 

The primary clinical characteristic of tuberous sclerosis of both types 1 and 2 are the occurrence of hamartomas at multiple anatomic sites.  Ocular lesions include those of the eyelids which often appear in early childhood along with other facial angiofibromas (formerly called adenoma sebaceum).  Of greater clinical significance are lesions of the optic nerve and retina reported in about 75% of patients.  The latter (astrocytic hamartomas) may appear as mulberry-like growths typically located in the peripapillary area or as flat translucent lesions located more peripherally.  These are usually static but aggressive growth with retinal detachment and neovascular glaucoma requiring enucleation has been reported in several patients.  Calcification of these lesions may occur in utero or early in life.  They are seldom of clinical significance although optic atrophy has been reported.  The ocular phenotype is similar in types 1 and 2.

Systemic Features: 

Hamartomas develop throughout the body in many organs such as the skin, brain, eye, kidney, and heart.  Ninety per cent of patients have skin lesions, including hypomelanotic patches called 'ashleaf' spots that can best be visualized under a Woods lamp.  Symptoms vary widely depending upon the location and size of the growths.  These appear as rhabdomyomas in the heart, angiomyolipomas in the kidneys, bone cysts, and oral fibromas.  Other intracranial growths such as subependymal astrocytomas and cortical tubers are evidence of CNS involvement that can interfere with brain function leading to seizures (in 80% of patients) and subnormal intellectual abilities (60-70% patients) as manifested by learning difficulties, subnormal IQs, as well as social and communication difficulties.   Hypoplasia of dental enamel with pitting in permanent teeth is seen in the majority of patients.  Some progression of tumor size and symptoms may occur.  Most hamartomas are benign but renal carcinoma has been reported in some patients.

There is some evidence that the clinical disease is more severe in this type (TSC2) than in type 1 (191100).  TSC2 has more hypomelanotic patches and brain tubers.  Cognitive defects are more severe.  Those with TSC2 mutations also have an earlier onset of seizures and a higher incidence of infantile spasms.

Genetics

This is the more severe and more common of the two tuberous sclerosis complex phenotypes.  It is caused by mutations in the TSC2 gene encoding tuberin on chromosome 16p13.3.  Genotyping is necessary to determine which mutation is responsible for the TS complex in each case as the phenotypic differences are inadequate to distinguish between types 1 and 2.

Many cases (two-thirds) occur sporadically but numerous reported pedigrees are consistent with autosomal dominant inheritance.  Type 1 TSC (191100) is caused by mutations in the TSC1 gene (9p34) encoding hamartin and is responsible for the disorder in about 25% of patients.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective preventative treatment exists but individual lesions can be surgically removed when indicated.

References
Article Title: 
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