Symptoms of hypochondrogenesis include: edema, limb undergrowth, spondyloepiphyseal dysplasia, short ribs, respiratory failure, short chin, upper limb undergrowth, thoracic hypoplasia, hypertelorism, hydrops fetalis, pulmonary hypoplasia, and a cleft palate.
The protein made by this gene forms type II collagen, a molecule found mostly in cartilage and in the clear gel that fills the eyeball (the vitreous).
Mutations in the COL2A1 gene interfere with the assembly of type II collagen molecules, which prevents bones from developing properly.
The face appears flat and oval-shaped, with widely spaced eyes, a small chin, and, in some cases, an opening in the roof of the mouth called a cleft palate.
Babies who live past the newborn period are usually reclassified as having spondyloepiphyseal dysplasia congenita, a related disorder on the spectrum of abnormal bone growth.