Knobloch syndrome is characterized by severe vision problems and skull defects. The most common features include extreme nearsightedness (high myopia), recurrent retinal detachment, and occipital encephalocele. There are three types of Knobloch syndrome, which can be distinguished by the underlying genetic cause. Knobloch syndrome type I is caused by genetic changes in the COL18A1 gene. The genes associated with Knobloch syndrome type 2 and type 3 have not been identified; however, Knobloch syndrome type 3 has been linked to a specific region on chromosome 17, known as 17q11.2. Knobloch syndrome follows an autosomal recessive pattern of inheritance.