GJB2

KID Syndrome

Clinical Characteristics
Ocular Features: 

Superficial punctate keratopathy leads to recurrent corneal erosions and eventually scarring and neovascularization.  Progressive opacification requiring PK often occurs.  These individuals may also suffer loss of eyebrows and eyelashes with trichiasis and thickening of the lid margins.  Corneal erosions and keratoconjunctivitis sicca cause incapacitating symptoms.

Systemic Features: 

The skin may be diffusely erythematous and scaly.  This often becomes patchier with well-demarcated areas especially in skin folds of the neck, axillae, and groin.  Older patients with likely autosomal recessive disease have hepatomegaly and may suffer cirrhosis and liver failure.  Short stature and mental retardation have also been noted.  The hearing loss is neurosensory in type.  Epidermal glycogen deposition has been found in one patient with the presumed recessive disorder.

In the presumed autosomal dominant disease, growth failure, mental retardation and liver disease do not seem to be present.  However, oral and skin squamous cell carcinomas, as well as malignant pilar tumors of the scalp may lead to early death.

Genetics

It is uncertain if one or more entities are represented by the KID syndrome.  Many cases are sporadic but others seem to be transmitted in autosomal recessive or autosomal dominant patterns.  The locus of the mutation is unknown in the recessive form.  In the dominant form, a mutation has been found in the connexin-26 gene, GJB2, gene located at 13q12.11.

See Hereditary Mucoepithelial Dysplasia (158310) for a somewhat similar but unique genodermatosis.  Another is IFAP (308205) but cataracts and hearing loss are not features.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

The use of ocular lubricating preparation may supply significant relief from symptoms but scarring may eventually necessitate penetrating keratoplasty.  The threat of skin cancers and fatal hepatic failure requires monitoring throughout life.

References
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