Brain Imaging Features in Knobloch Syndrome Type 1 due to COL18A1 Mutation
Rachel Garn1, Sedat Gul2, Arayamparambil Anilkumar2
1College of Medicine, SUNY Upstate Medical University, 2Department of Neurology, SUNY Upstate Medical University
Objective:

To reinforce brain abnormalities beyond encephalocele as features of Knobloch syndrome and expand on the heterogeneity of known neuroimaging findings.

Background:

Knobloch syndrome is a rare collagenopathy with predominant manifestations including brain and ocular abnormalities, along with cognitive impairments. Encephalocele is a characteristic finding; other brain anomalies can be seen though not often coexisting.

Design/Methods:
Case report, neuro imaging, and genetic testing
Results:

Case: A 14-year-old male, new immigrant from the Middle East with history of chronic vision impairment and developmental delay presented with seizures. Family history included epilepsy and blindness in his sister.

Ophthalmology exam showed pseudo-vossius ring in the left eye. Fundus exam showed large scattered rounded areas of depigmentation, scattered bone spicules in the right eye and scattered bone spicules and lacquer crack-like degenerative changes in the left eye. Visual acuity was 20/600 in the right eye and could not be tested in the left eye.

His neurological examination did not show any other cranial neuropathies. Motor and sensory examination was normal.

Brain MRI showed pachygyria and polymicrogyria in the bilateral frontal cortex. An arachnoid cyst with thinning of the overlying frontal bone was also noted. No encephalocele was present. There was posteriorly displaced lens on the right.

Genetic testing revealed a COL18A1 homozygous mutation, which is associated with autosomal recessive Knobloch syndrome.

Conclusions:

There are various structural abnormalities of brain seen in Knobloch syndrome even without encephalocele.

Genetic testing of COL18A1 is critical to making the diagnosis of Knobloch syndrome and is suggested in early onset vision impairment, seizures, and cognitive delays.

10.1212/WNL.0000000000208626
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