The three most common areas to be affected are the eyes, which are uncommonly large, joints and the mouth and facial structures.

[citation needed] The facial features of Marshall Syndrome include a flat midface, the appearance of large eyes, short upturned nose, and a round face.

The facial features of Stickler syndrome are less prominent but include a rather long flat face, and depressed nasal bridge.

[citation needed] The hearing loss associated with Stickler syndrome can be progressive and usually involves the high frequencies.

Because Marshall syndrome is an autosomal dominant hereditary disease, physicians can also note the characteristic appearance of the biological parent of the child.

A genetic test can be performed in Stickler syndrome diagnosis is made by doing a genetic test for the several collagen genes as well as other genes that are associated with Stickler as well as considering the presence and severity of Spondyloepiphyseal Dysplasia with association of reduced height and growth rate as well as other connective tissue features like skin hyperextensibility and poor wound healing.

It is an area of active research, also the genetic testing being expensive supports that the diagnosis is made depending on the features.

Yearly visits to an ophthalmologist or other eye care professional who has been informed of the diagnosis of Stickler or Marshall syndrome is important for all affected individuals.