Symptoms in people with Treacher Collins syndrome vary. Some individuals are so mildly affected that they remain undiagnosed, while others have moderate to severe facial involvement and life-threatening airway compromise. Most of the features of TCS are symmetrical and are already recognizable at birth.

The most common symptom of Treacher Collins syndrome is underdevelopment of the lower jaw and underdevelopment of the zygomatic bone. This can be accompanied by the tongue being retracted. The small mandible can result in a poor occlusion of the teeth or in more severe cases, trouble breathing or swallowing. Underdevelopment of the zygomatic bone gives the cheeks a sunken appearance.

The external ear is sometimes small, rotated, malformed, or absent entirely in people with TCS. Symmetric, bilateral narrowing or absence of the external ear canals is also described. In most cases, the bones of the middle ear and the middle ear cavity are misshapen. Inner ear malformations are rarely described. As a result of these abnormalities, a majority of the individuals with TCS have conductive hearing loss.

Most affected people also experience eye problems, including colobomata (notches) in the lower eyelids, partial or complete absence of eyelashes on the lower lid, downward angled eyelids, drooping of upper and lower eyelids, and narrowing of the tear ducts. Vision loss can occur and is associated with strabismus, refractive errors, and anisometropia. It can also be caused by severely dry eyes, a consequence of lower eyelid abnormalities and frequent eye infections.

Although an abnormally shaped skull is not distinctive for Treacher Collins syndrome, brachycephaly with bitemporal narrowing is sometimes observed. Cleft palate is also common.

Dental anomalies are seen in 60% of affected people, including tooth agenesis (33%), discoloration (enamel opacities) (20%), malplacement of the maxillary first molars (13%), and wide spacing of the teeth. In some cases, dental anomalies in combination with mandible hypoplasia result in a malocclusion. This can lead to problems with food intake and the ability to close the mouth.

Less common features of TCS may add to an affected person's breathing problems, including sleep apnea. Choanal atresia or stenosis is a narrowing or absence of the choanae, the internal opening of the nasal passages. Underdevelopment of the pharynx, can also narrow the airway.

Features related to TCS that are seen less frequently include nasal deformities, high-arched palate, macrostomia, preauricular hair displacement, cleft palate, hypertelorism, notched upper eyelid, and congenital heart defects.

The general public may associate facial deformity with developmental delay and intellectual disability, but more than 95% of people affected with TCS have normal intelligence. The psychological and social problems associated with facial deformity can affect quality of life in people with TCS.

The clinical presentation of HFM is quite variable. The severity may depend on the extent of the area with an insufficient blood supply "in utero", and the gestational age of the fetus at which this occurs. In some people, the only physical manifestation may be a small and underdeveloped external ear. In more severe cases, multiple parts of the face may be affected. Some people with HFM may have sensorineural hearing loss and decreased visual acuity or even blindness.

Goldenhar syndrome can be thought of as a particularly severe form of HFM, in which extracranial anomalies are present to some extent. Some of the internal organs (especially the heart, kidneys, and lungs) may be underdeveloped, or in some cases even absent altogether. The affected organs are typically on the same side as the affected facial features, but bilateral involvement occurs in approximately 10% of cases. Deformities of the vertebral column such as scoliosis may also be observed in Goldenhar syndrome.

While there is no universally accepted grading scale, the OMENS scale (standing for Orbital, Mandible, Ear, Nerves and Soft tissue) was developed to help describe the heterogeneous phenotype that makes up this sequence or syndrome.

Intellectual disability is not typically seen in people with HFM.

Signs and symptoms include:

- syndromic facies

- hearing loss

- facial paralysis

Individuals with Treacher Collins syndrome often have both cleft palate and hearing loss, in addition to other disabilities. Hearing loss is often secondary to absent, small, or unusually formed ears (microtia), and commonly results from malformations of the middle ear. Researchers have found that most patients with Treacher Collins syndrome have symmetric external ear canal abnormalities and symmetrically dysmorphic or absent ossicles in the middle ear space. Inner ear structure is largely normal. Most patients show a moderate hearing impairment or greater, and the type of loss is generally a conductive hearing loss. Patients with Treacher Collins syndrome exhibit hearing losses similar to those of patients with malformed or missing ossicles (Pron "et al.", 1993).

The condition is also known by various other names:

- Lateral facial dysplasia

- First and second branchial arch syndrome

- Oral-mandibular-auricular syndrome

- Otomandibular dysostosis

- Craniofacial microsomia

Ectodermal dysplasia is characterized by absent sweat glands resulting in dry (hypohydrotic), often scale-like skin, sparse and usually coarse scalp hair that is often blonde, sparse eyebrows and eyelashes, and small brittle nails. In addition, abnormalities of ectodermal derivatives, neuroectodermal derivatives, and mesectodermal derivatives are often found. The ectodermal derivative abnormalities can affect the epidermis including mammary, pituitary and sweat glands, as well as hairs, dental enamel, nails, lens, and the internal ear. Neuroectodermal derivatives that can be affected include sensory placodes, cutaneous pigmental cells, and hair buds. Mesectodermal derivatives affected can include the dermis, hypodermis, dentin, head muscles and conjunctival cells, cervicofacial vascular endothelial cells, and part of the maxillofacial skeleton.

The hypohydrotic symptoms of ectodermal dysplasia described above are evidenced not only in the skin of affected individuals, but also in their phonation and voice production. Because the vocal folds may not be as hydrated as is necessary during the adduction phase of vocal fold vibration (due to lack of lubrication), a complete seal may not be accomplished between the folds and mucosal wave movement may be disrupted. This results in air escapement between the folds and the production of breathy voice, which often accompanies the skin abnormalities of ectodermal dysplasia.

Nasodigitoacoustic syndrome is congenital and is characterized by a number of nasal, facial and cranial features. These include a broad and high, sometimes depressed nasal bridge (top of the nose, between the eyes) and a flattened nasal tip. This can give the nose a shortened, arch-like appearance. Hypertelorism (unusually wide-set eyes), prominent frontal bones and supraorbital ridge (the eyebrow ridge), bilateral epicanthic folds (an extra flap of skin over the eyelids), a broad forehead and an overall enlarged head circumference have also been observed. A bulging of the upper lip with an exaggerated cupid's bow shape, and maxillary hypoplasia (underdevelopment of the upper jaw) with retraction have also been reported.

Several anomalies affecting the digits (fingers and toes) have been observed with the syndrome. A broadening of the thumbs and big toes (halluces) was reported in two brothers. The broadening was apparent in all distal phalanges of the fingers, although the pinkies were unaffected yet appeared to be clinodactylic (warped, or bent toward the other fingers). Additional eports described this broadness of the thumbs and big toes, with brachydactyly (shortness) in the distal phalanges of the other digits except the pinkies in affected individuals. On X-rays of a two-year-old boy with the disorder, the brachydactyly was shown to be caused by shortening of epiphyses (joint-ends) of the distal phalanges. The broadness and brachydactyly of the big toes in particular may give them a stunted, rounded and stub-like appearance.

The auditory, or "acoustic" abnormalities observed with the syndrome include sensorineural hearing loss and hoarseness. Two affected Turkish brothers with a mild form of this hearing loss, and a hoarse voice were reported. A laryngoscopic examination of both brothers revealed swelling of the vocal cords, and a malformed epiglottis. Sensorineural-associated hearing impairment and hoarsness was also observed in a 10-year-old girl and her father, and in a number of other cases.

Other characteristics seen with the syndrome include developmental delay, growth retardation, pulmonary stenosis (an obstruction of blood-flow from the right ventricle of the heart to the pulmonary artery) with associated dyspnea (shortness of breath), and renal agenesis (failure of the kidneys to develop during the fetal period). Undescended testes, hyperactivity and aggressive behavior have also been noted.

There is much discrepancy in the literature regarding the exact nature of the facial clefting involved in EEC. Some authors claim that the clefting involved in EEC is always cleft lip +/- palate and use this marker as a means of distinguishing EEC from other syndromes, such as AEC syndrome (ankyloblepharon, ectodermal dysplasia, and clefting) in which other types of clefting are found. Other authors include cleft palate only (CPO) in conjunction with ectrodactyly and ectodermal dysplasia as sufficient for a diagnosis of EEC.

TCS is often first suspected with characteristic symptoms observed during a physical exam. However, the clinical presentation of TCS can resemble other diseases, making diagnosis difficult. The OMENS classification was developed as a comprehensive and stage-based approach to differentiate the diseases. This acronym describes five distinct dysmorphic manifestations, namely orbital asymmetry, mandibular hypoplasia, auricular deformity, nerve development, and soft-tissue disease.

Orbital symmetry

- O0: normal orbital size, position

- O1: abnormal orbital size

- O2: abnormal orbital position

- O3: abnormal orbital size and position

Mandible

- M0: normal mandible

- M1: small mandible and glenoid fossa with short ramus

- M2: ramus short and abnormally shaped

1. 2A: glenoid fossa in anatomical acceptable position

2. 2B: Temperomandibular joint inferiorly (TMJ), medially, anteriorly displaced, with severely hypoplastic condyle

- M3: Complete absence of ramus, glenoid fossa, and TMJ

Ear

- E0: normal ear

- E1: Minor hypoplasia and cupping with all structures present

- E2: Absence of external auditory canal with variable hypoplasia of the auricle

- E3: Malposition of the lobule with absent auricle, lobular remnant usually inferior anteriorly displaced

Facial nerve

- N0: No facial nerve involvement

- N1: Upper facial nerve involvement (temporal or zygomatic branches)

- N2: Lower facial nerve involvement (buccal, mandibular or cervical)

- N3: All branches affected

Soft tissue

- S0: No soft tissue or muscle deficiency

- S1: Minimal tissue or muscle deficiency

- S2: Moderate tissue or muscle deficiency

- S3: Severe tissue or muscle deficiency

The joint changes include hyperextensibility (double-jointedness) and arthritis. Babies and young children with Stickler syndrome usually have very hyperextensible joints. As an affected child gets older, they may experience pain and stiffness from overuse of a joint. Osteoarthritis of the large joints often develops during the third or fourth decade. The joint changes in Marshall syndrome are of the same type but to a lesser degree. There also may be changes in the bones that show up on X-ray but generally are not a problem.

Persons with Pierre Robin sequence (PRS) are at greater risk for hearing impairment than persons with cleft lip and/or palate without PRS. One study showed an average of 83% hearing loss in PRS, compared to 60% in cleft individuals without PRS (Handzic "et al.", 1995). Similarly, PRS individuals typically exhibit conductive, bilateral hearing losses that are greater in degree than in cleft individuals without PRS. Middle ear effusion is generally apparent, with no middle ear or inner ear malformations. Accordingly, management by ear tubes (myringotomy tubes) is often effective and may restore normal levels of hearing (Handzic "et al.", 1995).

People with distal 18q- frequently have conductive and/or sensorineural hearing loss. The degree of hearing loss may vary from a mild to a severe loss.

The most severe problem associated with Stickler syndrome is Pierre Robin syndrome. This refers to a cleft palate resulting from a very small lower jaw. During early fetal life, the roof of the mouth is normally open and the sides of the palate have to come together to close. If the jaw is too small, there is not enough room for the tongue which is then pushed up and gets in the way of the closing palate. Sometimes the chin is so small the baby has problems with eating and breathing if the tongue blocks the back of the throat. Cleft palate is found less frequently in Marshall Syndrome than in Stickler syndrome but still more frequently than in the general population.

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.

Individuals with distal 18q- may have problems with reflux. Hernias have also been reported.

Individuals with Stickler syndrome experience a range of signs and symptoms. Some people have no signs and symptoms; others have some or all of the features described below. In addition, each feature of this syndrome may vary from subtle to severe.

A characteristic feature of Stickler syndrome is a somewhat flattened facial appearance. This is caused by underdeveloped bones in the middle of the face, including the cheekbones and the bridge of the nose. A particular group of physical features, called the Pierre Robin sequence, is common in children with Stickler syndrome. Robin sequence includes a U-shaped or sometimes V-shaped cleft palate (an opening in the roof of the mouth) with a tongue that is too large for the space formed by the small lower jaw. Children with a cleft palate are also prone to ear infections and occasionally swallowing difficulties.

Many people with Stickler syndrome are very nearsighted (described as having high myopia) because of the shape of the eye. People with eye involvement are prone to increased pressure within the eye (ocular hypertension) which could lead to glaucoma and tearing or detachment of the light-sensitive retina of the eye (retinal detachment). Cataract may also present as an ocular complication associated with Stickler's Syndrome. The jelly-like substance within the eye (the vitreous humour) has a distinctive appearance in the types of Stickler syndrome associated with the COL2A1 and COL11A1 genes. As a result, regular appointments to a specialist ophthalmologist are advised. The type of Stickler syndrome associated with the COL11A2 gene does not affect the eye.

People with this syndrome have problems that affect things other than the eyes and ears. Arthritis, abnormality to ends of long bones, vertebrae abnormality, curvature of the spine, scoliosis, joint pain, and double jointedness are all problems that can occur in the bones and joints. Physical characteristics of people with Stickler can include flat cheeks, flat nasal bridge, small upper jaw, pronounced upper lip groove, small lower jaw, and palate abnormalities, these tend to lessen with age and normal growth and palate abnormalities can be treated with routine surgery.

Another sign of Stickler syndrome is mild to severe hearing loss that, for some people, may be progressive (see hearing loss with craniofacial syndromes). The joints of affected children and young adults may be very flexible (hypermobile). Arthritis often appears at an early age and worsens as a person gets older. Learning difficulties, not intelligence, can also occur because of hearing and sight impairments if the school is not informed and the student is not assisted within the learning environment.

Stickler syndrome is thought to be associated with an increased incidence of mitral valve prolapse of the heart, although no definitive research supports this.

Mondini dysplasia, also known as Mondini malformation and Mondini defect, is an abnormality of the inner ear that is associated with sensorineural hearing loss.

This deformity was first described in 1791 by Mondini after examining the inner ear of a deaf boy. The Mondini dysplasia describes a cochlea with incomplete partitioning and a reduced number of turns, an enlarged vestibular aqueduct and a dilated vestibule. A normal cochlea has two and a half turns, a cochlea with Mondini dysplasia has one and a half turns; the basal turns being normally formed with a dilated or cystic apical turn to the cochlear. The hearing loss can deteriorate over time either gradually or in a step-wise fashion, or may be profound from birth.

Hearing loss associated with Mondini dysplasia may first become manifest in childhood or early adult life. Some children may pass newborn hearing screen to lose hearing in infancy but others present with a hearing loss at birth. Hearing loss is often progressive and because of the associated widened vestibular aqueduct may progress in a step-wise fashion associated with minor head trauma. Vestibular function is also often affected. While the hearing loss is sensorineural a conductive element may exist probably because of the third window effect of the widened vestibular aqueduct. The Mondini dysplasia can occur in cases of Pendred Syndrome and Branchio-oto-renal syndrome and in other syndromes, but can occur in non-syndromic deafness.

The incidence of this condition is <1 per million population. It is found only in females as all affected males die before birth. Teeth with large roots (radiculomegaly), heart defects, and small eyes (microphthalmia) are the characteristic triad found in this syndrome.

Typical features of the condition include:

- Face

- Deep set eyes

- Broad nasal tip divided by a cleft

- Eyes

- Microphthalmia (small eyes)

- Early cataracts

- Glaucoma

- Teeth

- Radiculomegaly (teeth with very large roots)

- Delayed loss of primary teeth

- Missing (oligodontia) or abnormally small teeth

- Misaligned teeth

- Defective tooth enamel.

- Heart defects

- Atrial and/or ventricular defects

- Mitral valve prolapse

- Mild mental retardation and conductive or sensorineural hearing loss may occur.

Symptoms of otodental syndrome can and usually appear in early development and progress with age. Although the specific frequency of the symptoms is not known, the duration is recognized to be for life; assuming no treatment has been undergone. The symptoms are variable to each individual, can range greatly in severity and are dependent on gene expression.

More severe symptoms include:

- Globodontia – an abnormal condition that can occur in both primary and secondary tooth development, in which the molars and canines are greatly enlarged. It refers to the enlarged bulbous fused malformed posterior teeth with almost no discernible cusps or grooves. The molars are known to have a rounded globe-like shape. Can attribute to pain.

- Sensorineural hearing loss (SNHL) – also known as nerve related hearing loss, is a form of hearing loss associated with complications within the inner ear.

- Taurodontism – known as a condition in which the body of a tooth is enlarged at the expense of the roots. This results in an enlarged pulp chamber, lack of proper bonding at the cementoenamel junction, and can cause the pulpal floor to be displaced towards the root. Discomfort and pain are usually associated with these characteristics.

- Endodontic-Periodontic lesions – oral lesions that can potentially form into abscesses. May cause further soreness and pain.

Other possible, less severe, symptoms involve:

- Absent premolars – individuals suffering from otodental syndrome will typically lack the ability to develop premolars due to its genetic related affects.

- Ocular coloboma – an existent hole within the eye of the individual. The hole can be present in either the iris, choroid, optic disc, or retina and is acquired during early/prenatal development. Individuals with these symptoms may exhibit sensitivity to light, blurred vision, and/or blind spots; depending on the size of the missing tissue and its location in the eye.

Features of YVS include growth retardation before and after birth, defective growth of the bones of the skull along with complete or partial absence of the shoulder blades and characteristic facial features. Additional symptoms may include abnormalities of the fingers and/or toes. In most cases, infants with this disorder experience severe feeding problems and respiratory difficulties. In addition, affected infants may have heart defects.

Because collagen plays an important role in the development of the body, people with Kniest Dysplasia will typically have their first symptoms at birth. These symptoms can include:.

- Musculoskeletal Problems

- Short limbs

- Shortened body trunk

- Flattened bones in the spine

- kyphoscoliosis

- Scoliosis (Lateral curvature of the spine)

- Early development of arthritis

- Respiratory problems

- Respiratory tract infection

- Difficulty breathing

- Eye problems

- Severe myopia (near-sightedness)

- Cataract (cloudiness in the lens of the eye)

- Hearing problems

- progressive hearing loss

- ear infections

Most symptoms are chronic and will continue to worsen as the individual ages. It is essential to have regular checkups with general doctors, orthopedist, ophthalmologists, and/or otorhinolaryngologists. This will help to detect whether there are any changes that could cause concern.

The distinctive characteristics of OSMED include severe bone and joint problems and very severe hearing loss. This disorder affects the epiphyses, the parts of the bone where growth occurs. People with the condition are often shorter than average because the bones in their arms and legs are unusually short. Other skeletal signs include enlarged joints, short hands and fingers, and flat bones of the spine (vertebrae). People with the disorder often experience back and joint pain, limited joint movement, and arthritis that begins early in life. Severe high-tone hearing loss is common. Typical facial features include protruding eyes; a sunken nasal bridge; an upturned nose with a large, rounded tip; and a small lower jaw. Some affected infants are born with an opening in the roof of the mouth, which is called a cleft palate.

This condition is characterised by symmetrical lesions on the temples resembling forceps marks. It is characterized a puckered skin due to a virtual absence of subcutaneous fat. It is apparent at birth. Other lesions that may be present include puffy, wrinkled skin around the eyes and/or abnormalities of the eyelashes, eyebrows, and eyelids. The eyebrows may be up slanting or outward slanting. Occasionally the bridge of the nose may appear flat, while the tip may appear unusually rounded. The chin may be furrowed. The upper lip may be prominent with a down turned mouth. Other features that have been reported include dysplastic and low set ears, linear radiatory impressions on the forehead and congenital horizontal nystagmus.

Those with the Setleis syndrome may be missing eyelashes on both the upper and lower lids or may have multiple rows of lashes on the upper lids but none on the lower lids.A possible association with intra abdominal cancer has been reported but to date this has not been confirmed in other studies.

EEM syndrome exhibits a combination of prominent symptoms and features. These include: ectodermal dysplasia (systemic malformations of ectodermal tissues), ectrodactyly ("lobster claw" deformity in the hands and feet), macular dystrophy (a progressive eye disease), syndactyly (webbed fingers or toes), hypotrichosis (a type of hair-loss), and dental abnormalities (hypodontia).

Clinical expressions of PPS are highly variable, but include the following:

- Limb findings: an extensive web running from behind the knee down to the heel (90%), malformed toenails, and webbed toes.

- Facial findings: cleft palate with or without cleft lip (75%), pits in the lower lip (40%), and fibrous bands in the mouth known as syngnathia (25%).

- Genital findings (50%): hypoplasia of the labia majora, malformation of the scrotum, and cryptorchidism.

This disorder is characterized by unusual facial features, including prominent, wide-set eyes with outer corners that point downward; a short bulbous nose with a flat nasal bridge; ears that are rotated backward; and a widow's peak hairline.

Individuals with Donnai–Barrow syndrome have severe hearing loss caused by abnormalities of the inner ear (sensorineural hearing loss). In addition, they often experience vision problems, including extreme nearsightedness (high myopia), detachment or deterioration of the light-sensitive tissue in the back of the eye (the retina), and progressive vision loss. Some have a gap or split in the colored part of the eye (iris coloboma).

In almost all people with Donnai–Barrow syndrome, the tissue connecting the left and right halves of the brain (corpus callosum) is underdeveloped or absent. Affected individuals may also have other structural abnormalities of the brain. They generally have mild to moderate intellectual disability and developmental delay.

People with Donnai–Barrow syndrome may also have a hole in the muscle that separates the abdomen from the chest cavity (the diaphragm), which is called a diaphragmatic hernia. This potentially serious birth defect allows the stomach and intestines to move into the chest and possibly crowd the developing heart and lungs. An opening in the wall of the abdomen (an omphalocele) that allows the abdominal organs to protrude through the navel may also occur in affected individuals. Occasionally people with Donnai–Barrow syndrome have abnormalities of the intestine, heart, or other organs and scoliosis.