SNP Shot: Genomic Insights

Knobloch syndrome is a rare disorder marked by significant visual impairment and a cranial malformation.

A defining characteristic of Knobloch syndrome is severe myopia (extreme nearsightedness). Furthermore, various other eye abnormalities are frequently observed in individuals with this syndrome. The majority of those affected experience vitreoretinal degeneration, a breakdown of the vitreous and retina, two key structures within the eye. The vitreous is the gel-like substance that fills the eyeball, while the retina is the light-sensitive tissue located at the rear of the eye. Vitreoretinal degeneration frequently results in retinal detachment, where the retina separates from the back of the eye. Affected individuals may also exhibit abnormalities in the macula, the central region of the retina crucial for sharp, central vision required for tasks like reading, driving, and facial recognition. Due to these vitreous, retinal, and macular abnormalities, individuals with Knobloch syndrome often experience blindness in one or both eyes.

Another key feature of Knobloch syndrome is an occipital encephalocele, a skull defect involving a sac-like protrusion of the brain (encephalocele) through an opening in the occipital bone at the base of the skull. Some individuals with Knobloch syndrome have presented with different skull defects in the occipital area, and it's not fully established if these defects are always true encephaloceles. While encephaloceles in other conditions can be linked to intellectual disability, most individuals with Knobloch syndrome possess normal cognitive abilities.

Inheritance:

This syndrome follows an autosomal recessive inheritance pattern. This means that both copies of the responsible gene in each cell must carry mutations for the condition to manifest. Individuals with autosomal recessive conditions inherit one mutated copy of the gene from each parent, who are typically carriers and do not exhibit symptoms of the condition themselves.