A Case of Knobloch Syndrome With Lens Dislocation Resembling Homocystinuria

Area of Science:

• Ophthalmology
• Genetics
• Neurology

Background:

• Lifelong visual impairment can stem from various genetic and degenerative conditions.
• Knobloch syndrome is a rare genetic disorder characterized by ocular and central nervous system abnormalities.
• Adult presentations of rare genetic syndromes are often challenging to diagnose.

Purpose of the Study:

• To report a unique adult case of Knobloch syndrome type 1.
• To detail the ophthalmologic and neurologic findings in this patient.
• To emphasize the importance of genetic testing in diagnosing complex visual impairments.

Main Methods:

• Ophthalmologic examination including assessment of visual acuity, refractive error, and funduscopy.
• Neurologic evaluation with lumbar puncture for cerebrospinal fluid pressure measurement and magnetic resonance imaging (MRI).
• Whole-exome sequencing to identify the genetic mutation responsible for the patient's condition.

Main Results:

• The patient presented with severe myopia, vitreoretinal degeneration, phthisis bulbi, and lens dislocation.
• Neurologic findings included elevated intracranial pressure, white matter changes on MRI, and polymicrogyria.
• Genetic analysis revealed a homozygous frameshift mutation in COL18A1, confirming Knobloch syndrome type 1.

Conclusions:

• This case demonstrates an atypical adult presentation of Knobloch syndrome type 1.
• The ocular findings mimicked other conditions, underscoring the need for comprehensive genetic analysis.
• Accurate genetic diagnosis is crucial for understanding disease mechanisms and potential management strategies for rare syndromes.