motor delay

Knobloch Syndrome 2

Clinical Characteristics
Ocular Features: 

In an 18 month infant, ectopia lentis, cataract, and myopia with poor vision were noted.  This individual subsequently developed retinal degeneration and a serous retinal detachment.

Systemic Features: 

Only one patient has been reported.  While the clinical signs resemble Knobloch 1 syndrome, brain imaging does not reveal malformations in this syndrome.  The only systemic sign, in addition to an occipital encephalocele, is a minor delay in fine motor skills.

Genetics

This autosomal recessive disorder results from homozygous loss of function mutations in the ADAMTS18 gene (16q23.1).  The gene product has been found in the lens and retina in the murine eye.

Mutations in ADAMTS18 have also been found in the syndrome of Micorcornea, Myopia, Chorioretinal atrophy, and Telecanthus.  It may also be responsible for a retinal dystrophy.

Knobloch 2 syndrome was identified in a single female born to consanguineous parents.

This disorder is separate to Knobloch 1 syndrome (267750) based on the causative mutations.  A third type, KNO3, has been proposed since the Knobloch clinical features were found in a 4-generation consanguineous Pakistani family but the phenotype mapped to 17q11.2.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

The skull defect can be closed and the lenses can be removed if indicated.

References
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