Knobloch–Layer syndrome

Knobloch–Layer syndrome is a rare genetic disorder characterized by severe vision problems, including retinal detachment and myopia (nearsightedness), as well as a distinctive layer of tissue (known as a Knobloch layer) at the back of the eye. This condition may also be associated with other systemic abnormalities, including craniofacial anomalies, neurological issues, and, in some cases, skin and skeletal abnormalities. The syndrome is named after the researchers who first described it in the medical literature.

Causes

Knobloch–Layer syndrome is caused by mutations in the COL18A1 gene, which provides instructions for making a portion of a larger protein known as collagen XVIII. This protein plays a crucial role in the structure and integrity of basement membranes in various tissues, including the eye. The mutations lead to a deficiency or dysfunction of collagen XVIII, disrupting the normal structure and function of the eye and other affected organs.

Symptoms

The hallmark symptom of Knobloch–Layer syndrome is a severe retinal detachment, which can lead to blindness if not treated promptly. Other eye-related symptoms include high myopia and abnormalities in the vitreous, the gel-like substance filling the eye. Beyond the eye, affected individuals may have a range of symptoms, including but not limited to:

• Skull and facial abnormalities (e.g., occipital encephalocele)
• Neurological issues
• Skin and skeletal abnormalities

Diagnosis

Diagnosis of Knobloch–Layer syndrome is based on clinical examination and the presence of characteristic symptoms. Genetic testing can confirm the diagnosis by identifying mutations in the COL18A1 gene.

Treatment

There is no cure for Knobloch–Layer syndrome, and treatment focuses on managing symptoms and preventing complications. Surgical intervention may be necessary to repair retinal detachments and prevent blindness. Other treatments are symptomatic and supportive, including vision aids, physical therapy, and, in some cases, surgery for skeletal abnormalities.

Prognosis

The prognosis for individuals with Knobloch–Layer syndrome varies depending on the severity of the symptoms and the success of treatments, particularly for retinal detachments. Early detection and treatment of eye-related symptoms are crucial for preserving vision.