Child with<unk>  showing characteristic facial features. Cranial sutures A defining characteristic of<unk>  is craniosynostosis, which results in an abnormal head shape. This is present in combinations of: frontal bossing, trigonocephaly (fusion of the metopic suture), brachycephaly (fusion of the coronal suture), dolichocephaly (fusion of the sagittal suture), plagiocephaly (unilateral premature closure of lambdoid and coronal sutures), oxycephaly (fusion of coronal and lambdoidal sutures), and complex craniosynostosis (premature closure of some or all sutures). Exophthalmos (bulging eyes due to shallow eye sockets after early fusion of surrounding bones), hypertelorism (greater than normal distance between the eyes), and psittichorhina (beak-like nose) are also very common features. Other facial characteristics that are present in many cases include external strabismus and hypoplastic maxilla (insufficient growth of the midface), which results in relative mandibular prognathism (protruding chin) and gives the effect of the patient having a concave face. Most symptoms are secondary to the abnormal skull structure. Approximately 30% of people with<unk>  develop hydrocephalus. Sensorineural hearing loss is present in some cases. The abnormalities in the manner in which the eyes fit in the eye sockets can cause vision problems, the most common of which is corneal exposure that can lead to visual impairment. Some people with the condition have a restricted airway and can experience severe problems breathing. Common features are a narrow/high-arched palate, posterior bilateral crossbite, hypodontia (missing some teeth), and crowding of teeth. Due to maxillary hypoplasia, people with<unk>  generally have a considerable permanent underbite.
Crouzon syndrome
Sandhoff disease
Okamoto syndrome
Yushō disease
Barakat syndrome
Friedreich's ataxia
Stratton Parker syndrome
Satoyoshi syndrome