The following are symptoms characteristic with individuals having the disorder. Individuals may display some, most, or all of these symptoms throughout the course of their life, though symptoms may vary with each patient.

- Abnormal hair (coarse, thick, brittle)

- Calvarial hypomineralization (soft skull)

- Y-shaped cataracts by 1–2 years of age

- Skeletal defects

- Hypertelorism (wide-set eyes)

- Facial dysmorphisms

- Late-closing fontanels

- Abnormal accumulation of proteins in the endoplasmic reticulum

- Scoliosis

- Broad forehead, nose

- Missing, small teeth or abnormal teeth positioning

- Poor skull calcification

- Flat foot

- Motor delay

- Abnormal vertebrae

- Prominent forehead and brow

- High nose bridge

- Capillary hemangioma

- Delayed tooth eruption

- Long upper lip groove

- Large mouth

- High arched palate

- Narrow hips and rib cage

- Thin lips

- Narrow and sloping shoulders

- Hyperpigmentation

- Hyperextensible joints

Onset of the disease is in neonatal development and infancy, and symptoms tend to become evident soon after birth.

This condition is a skeletal dysplasia characterized by short stature, mild brachydactyly, kyphoscoliosis, abnormal gait, enlarged knee joints, precocious osteoarthropathy, platyspondyly, delayed epiphyseal ossification, mild metaphyseal abnormalities, short stature and short and bowed legs. Intelligence is normal.

Some patients may manifest premature pubarche and hyperandrogenism.

Other features that may form part of the syndrome include precocious costal calcification, small iliac bones, short femoral necks, coxa vara, short halluces and fused vertebral bodies.

Skeletal anomalies aren't present at birth but develop in the individual and include delayed bone maturation, slender long tubular bones, and tall vertebral bodies. Joint hyper-mobility and increased risk of hip dislocation has been presented in individuals. Abnormal spinal curvature, either kyhoscholiosis or hyperlordosis, causing back pain can also be experienced from this disorder.

Many of the physical features associated with the disorder are congenital. Characteristic craniofacial abnormalities typically include a long, narrow head that is disproportionate to the body size, a broad and prominent forehead, and a triangular-shaped face with a hypoplastic midface, pointed chin, prominent mouth, fleshy tipped upturned nose, large ears, and full lips. The teeth may be abnormally crowded together in some affected individuals.

Spondyloepimetaphyseal dysplasia, Pakistani type is a form of spondyloepimetaphyseal dysplasia involving "PAPSS2" (also known as "ATPSK2"). The condition is rare.

Cranio–lenticulo–sutural dysplasia (CLSD, or Boyadjiev-Jabs syndrome) is a neonatal/infancy disease caused by a disorder in the 14th chromosome. It is an autosomal recessive disorder, meaning that both recessive genes must be inherited from each parent in order for the disease to manifest itself. The disease causes a significant dilation of the endoplasmic reticulum in fibroblasts of the host with CLSD. Due to the distension of the endoplasmic reticulum, export of proteins (such as collagen) from the cell is disrupted.

The production of SEC23A protein is involved in the pathway of exporting collagen (the COPII pathway), but a missense mutation causes and underproduction of SEC23A which inhibits the pathway, affecting collagen secretion. This decrease in collagen secretion can lead to the bone defects that are also characteristic of the disease, such as skeletal dysplasia and under-ossification. Decreased collagen in CLSD-affected individuals contributes to improper bone formation, because collagen is a major protein in the extracellular matrix and contributes to its proper mineralization in bones. It has also been hypothesized that there are other defects in the genetic code besides SEC23A that contribute to the disorder.

Cleidocranial dysostosis is a general skeletal condition so named from the collarbone (cleido-) and cranium deformities which people with it often have.

People with the condition usually present with a painless swelling in the area of the clavicles at 2–3 years of age. Common features are:

- Clavicles (collarbones) can be partly missing leaving only the medial part of the bone. In 10% cases, they are completely missing. If the collarbones are completely missing or reduced to small vestiges, this allows hypermobility of the shoulders including ability to touch the shoulders together in front of the chest. The defect is bilateral 80% of the time. Partial collarbones may cause nerve damage symptoms and therefore have to be removed by surgery.

- The mandible is prognathic due to hypoplasia of maxilla (micrognathism) and other facial bones.

- A soft spot or larger soft area in the top of the head where the fontanelle failed to close, or the fontanelle closes late.

- Bones and joints are underdeveloped. People are shorter and their frames are smaller than their siblings who do not have the condition.

- The permanent teeth include supernumerary teeth. Unless these supernumeraries are removed they will crowd the adult teeth in what already may be an underdeveloped jaw. If so, the supernumeraries will probably need to be removed to make space for the adult teeth. Up to 13 supernumarary teeth have been observed. Teeth may also be displaced. Cementum formation may be deficient.

- Failure of eruption of permanent teeth.

- Bossing (bulging) of the forehead.

- Open skull sutures, large fontanelles.

- Hypertelorism.

- Delayed ossification of bones forming symphysis pubis, producing a widened symphysis.

- Coxa vara can occur, limiting abduction and causing Trendelenburg gait.

- Short middle fifth phalanges, sometimes causing short and wide fingers.

- Vertebral abnormalities.

- On rare occasions, brachial plexus irritation can occur.

- Scoliosis, spina bifida and syringomyelia have also been described.

Other features are: parietal bossing, basilar invagination (atlantoaxial impaction), persistent metopic suture, abnormal ear structures with hearing loss, supernumerary ribs, hemivertebrae with spondylosis, small and high scapulae, hypoplasia of illiac bones, absence of the pubic bone, short / absent fibular bones, short / absent radial bones, hypoplastic terminal phalanges.

Individuals affected by ischiopatellar dysplasia commonly have abnormalities of the patella and pelvic girdle, such as absent or delayed patellar and ischial ossification as well as infra-acetabular axe-cut notches. Patellae are typically absent or small in these individuals, when patellae are present they are small and laterally displaced or dislocated. In addition, abnormalities in other parts of their skeleton and dysmorphic features are common in those affected. Other features that have been identified in patients with ischiopatellar dysplasia include foot anomalies, specifically flat feet (pes planus), syndactylism of the toes, short fourth and fifth toes, and a large gap between the first and second toes, femur anomalies, cleft palate, and craniofacial dysmorphisms.

Common signs of Say–Meyer syndrome are trigonocephaly as well as head and neck symptoms. The head and neck symptoms come in the form of craniosynostosis affecting the metopic suture (the dense connective tissue structure that divides the two halves of the skull in children which usually fuse together by the age of six). Symptoms of Say–Meyer syndrome other than developmental delay and short stature include

- Intellectual disability.

- Low-set ears/posteriorly rotated ears

- Intellectual deficit as well as learning disability

- Intrauterine growth retardation (poor growth of a baby while it is in the mother's womb)

- Posterior fontanel

- Premature synostosis of the lambdoid suture (the fusion of the bones to the joint is premature)

- Narrow forehead

- Trigonocephaly (a frontal bone anomaly that is characterized by a premature fusion of the bones which gives the forehead a triangular shape)

- Hypotelorism or hypertelorism (reduced or increased width between the eyes)

- Craniosynostosis (when one or more seam-like junctions between two bones fuses by turning into bone. This changes the growth pattern of the skull)

- Low birth weight and height

The affected patients sometimes show a highly arched palate, clinodactyly (a defect in which toes or fingers are positioned abnormally) and ventricular septal defect (a heart defect that allows blood to pass directly from left to the right ventricle which is caused by an opening in the septum). Overall, Say–Meyer syndrome impairs growth, motor function, and mental state.

Below are the common clinical features of those diagnosed with Floating–Harbor syndrome. Patients will show varying degrees of some or all FHS symptoms. Facial abnormalities are the most defining aspects of those diagnosed with this disease.

Being an extremely rare autosomal genetic disorder, differential diagnosis has only led to several cases since 1972. Initial diagnosis lends itself to facial abnormalities including sloping forehead, maxillary hypoplasia, nasal bridge depression, wide mouth, dental maloclusion, and receding chin. Electroencephalography (EEG), computed tomography (CT) scanning, and skeletal survey are further required for confident diagnosis. Commonly, diffuse cartilage calcification and brachytelephalangism are identified by X-radiation (X-ray), while peripheral pulmonary arterial stenosis, hearing loss, dysmorphic facies, and mental retardation are confirmed with confidence by the aforementioned diagnostic techniques.

Opsismodysplasia can be characterized by a delay in bone maturation, which refers to "bone aging", an expected sequence of developmental changes in the skeleton corresponding to the chronological age of a person. Factors such as gender and ethnicity also play a role in bone age assessment. The only indicator of physical development that can be applied from birth through mature adulthood is bone age. Specifically, the age and maturity of bone can be determined by its state of ossification, the age-related process whereby certain cartilaginous and soft tissue structures are transformed into bone. The condition of epiphyseal plates (growth plates) at the ends of the long bones (which includes those of the arms, hands, legs and feet) is another measurement of bone age. The evaluation of both ossification and the state of growth plates in children is often reached through radiography (X-rays) of the carpals (bones of the hand and wrist). In opsismodysplasia, the process of ossification in long bones can be disrupted by a failure of ossification centers (a center of organization in long bones, where cartilage cells designated to await and undergo ossification gather and align in rows) to form. This was observed in a 16-month-old boy with the disorder, who had no apparent ossification centers in the carpals (bones of the hand and wrist) or tarsals (bones of the foot). This was associated with an absence of ossification in these bones, as well as disfigurement of the hands and feet at age two. The boy also had no ossification occurring in the lower femur (thigh bone) and upper tibia (the shin bone).

As a result of the changes to the developing embryo, the symptoms are very pronounced features, especially in the face. Low-set ears are a typical characteristic, as in all of the disorders which are called branchial arch syndromes. The reason for this abnormality is that ears on a foetus are much lower than those on an adult. During normal development, the ears "travel" upward on the head; however, in Crouzon patients, this pattern of development is disrupted. Ear canal malformations are extremely common, generally resulting in some hearing loss. In particularly severe cases, Ménière's disease may occur.

The most notable characteristic of Crouzon syndrome is craniosynostosis, as described above; however it usually presents as brachycephaly resulting in the appearance of a short and broad head. 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 symptoms. Additionally, external strabismus is a common occurrence, which can be thought of as opposite from the eye position found in Down syndrome. Lastly, hypoplastic maxilla (insufficient growth of the midface) results in relative mandibular prognathism (chin appears to protrude despite normal growth of mandible) and gives the effect of the patient having a concave face. Crouzon syndrome is also associated with patent ductus arteriosus (PDA) and aortic coarctation.

For reasons that are not entirely clear, most Crouzon patients also have noticeably shorter humerus and femur bones relative to the rest of their bodies than members of the general population. A small percentage of Crouzon patients also have what is called "Type II" Crouzon syndrome, distinguished by partial syndactyly.

The syndrome consists of severe micrognathia, cleft lip and/or palate, hypoplasia or aplasia of the postaxial elements of the limbs, coloboma of the eyelids, and supernumerary nipples. Additional features of the syndrome include

downward-slanting palpebral fissures, malar hypoplasia, malformed ears, and a broad nasal ridge. Other features include supernumerary vertebrae and other vertebral segmentation and rib defects, heart defects (patent ductus arteriosus, ventricular septal defect and Ostium primum atrial septal defect), lung disease from chronic infection, single umbilical artery, absence of the hemidiaphragm, hypoplasia of the femora, ossification defects of the ischium and pubis, bilobed tongue, lung hypoplasia, and renal reflux.

There are four main signs of acalvaria: absence of the flat bones of the cranial vault, absence of the dura mater and muscles associated with it, skull abnormalities, and the absence of a skull cap. This condition can be diagnosed prior to birth using ultrasonography. Physicians often use magnetic resonance imaging to confirm the diagnosis because in utero, acalvaria is sometimes confused with anencephaly or encephalocele. A distinguishable difference is that with anencephaly, the cerebral hemispheres are missing, but with acalvaria, all parts of the cerebrum are usually present and developed, whereas parts of the calvarium are missing.

Opsismodysplasia is a type of skeletal dysplasia (a bone disease that interferes with bone development) first described by Zonana and associates in 1977, and designated under its current name by Maroteaux (1984). Derived from the Greek "opsismos" ("late"), the name "opsismodysplasia" describes a delay in bone maturation. In addition to this delay, the disorder is characterized by (short or undersized bones), particularly of the hands and feet, delay of ossification (bone cell formation), platyspondyly (flattened vertebrae), irregular metaphyses, an array of facial aberrations and respiratory distress related to chronic infection. Opsismodysplasia is congenital, being apparent at birth. It has a variable mortality, with some affected individuals living to adulthood. The disorder is rare, with an incidence of less than 1 per 1,000,000 worldwide. It is inherited in an autosomal recessive pattern, which means the defective (mutated) gene that causes the disorder is located on an autosome, and the disorder occurs when two copies of this defective gene are inherited. No specific gene has been found to be associated with the disorder. It is similar to spondylometaphyseal dysplasia, Sedaghatian type.

The cranium consists of three main sections including the base of the cranium (occipital bone), the face (frontal bone), and the top (parietal bones) and sides (temporal bone) of the head. Most of the bones of the cranium are permanently set into place prior to birth. However, the temporal and parietal bones are separated by sutures, which remain open, allowing the head to slightly change in shape during childbirth. The cranial sutures eventually close within the first couple of years following birth, after the brain has finished growing.

In individuals with SCS, the coronal suture separating the frontal bones from the parietal bones, closes prematurely (craniosynostosis), occasionally even before birth. If the coronal suture closes asymmetrically or unilaterally, then the face and forehead will form unevenly, from side-to-side. People with SCS have pointy, tower-like heads because their brain is growing faster than their skull, resulting in increased intracranial pressure (ICP) and causing the top of the head and/or forehead to bulge out to allow for brain growth. The face appears uneven, particularly in the areas of the eyes and cheeks, and the forehead appears wide and tall.

Because of the abnormal forehead, there is less space for the normal facial features to develop. This results in shallow eye sockets and flat cheekbones. The shallow eye sockets make the eyes more prominent or bulging and cause the eyes to be more separated than normal (hypertelorism). The underdeveloped eye sockets, cheekbones, and lower jaw cause the face to appear flat. Furthermore, the minor downward slant of the eyes along with the drooping eyelids (ptosis) adds to the overall unevenness of the face.

For unknown reasons, children born with FOP have deformed big toes, possibly missing a joint or simply presenting with a notable lump at the minor joint. The first "flare-up" that leads to the formation of FOP bones usually occurs before the age of 10. The bone growth progresses from the top downward, just as bones grow in fetuses. A child with FOP will typically develop bones starting at the neck, then on the shoulders, arms, chest area and finally on the feet.

Specifically, ossification is typically first seen in the dorsal, axial, cranial and proximal regions of the body. Later the disease progresses in the ventral, appendicular, caudal and distal regions of the body. However, it does not necessarily occur in this order due to injury-caused flare-ups. Often, the tumor-like lumps that characterize the disease appear suddenly. This condition causes loss of mobility to affected joints, including inability to fully open the mouth limiting speech and eating. Extra bone formation around the rib cage restricts the expansion of lungs and diaphragm causing breathing complications.

Since the disease is so rare, the symptoms are often misdiagnosed as cancer or fibrosis. This leads physicians to order biopsies, which can exacerbate the growth of these lumps. However, those born with FOP tend to have malformed toes or thumbs which help distinguish this disorder from other skeletal problems.

The median age of survival is 40 years with proper management. However, delayed diagnosis, trauma and infections can decrease life expectancy.

The age of onset is almost always before 3 months of age. Many infants are born preterm (1/3 cases) and dysmature. The babies are frequently small for dates. The placenta may be abnormal with non-specific inflammation on histology. Umbilical cord anomalies have occasionally been reported. In severe cases, signs in the brain may be detected on prenatal ultrasound.

The presentation is pleiomorphic, making the diagnosis difficult, but the most common features of this disease involve the skin, joints, and central nervous system.

All have a maculopapular urticarial skin rash that is often present at birth (75% cases). It is probably more correctly described as an urticarial-like rash. The presence of the rash varies with time, and biopsy of these skin lesions shows a perivascular inflammatory infiltrate including granulocytes.

In about 35-65% of cases, arthritis occurs. Joint signs are variably expressed and can lead to transient swelling without sequelae between crises, or to unpredictable anomalies of growth cartilage and long bones epiphyses suggestive of a pseudo-tumour. Biopsies reveal hypertrophic cartilage without inflammatory cells. This most commonly affects the large joints (knees, ankles, elbows, and wrists) but may also involve the small joints of the hands and feet. It is usually bilateral and painful. A common and characteristic feature is giant kneecaps. Severe cases may result in contractures (joint deformities).

Most patients eventually have neurological problems. These manifest themselves in three principal ways: chronic meningitis, involvement of both the optic tract and eye, and sensorineural hearing loss. The chronic meningitis presents with the features of chronically raised intracranial pressure: headaches, vomiting, ventriculomegaly, hydrocephalus, macromegaly, cerebral atrophy, and optic atrophy. Some of these features may be evidenced on prenatal ultrasound. In 50% of cases, intellectual deficit occurs. Seizures occur in 25% of cases, but other manifestations are rare. Histological examination shows infiltration of the meninges with polymorphs.

Ocular manifestations occur in 80% of cases and include uveitis (70%), papillary involvement, conjunctivitis, and optical neuritis. If untreated, these may result in blindness (25%). The sensorineural hearing loss occurs in 75%, and tends to be progressive leading to deafness in 20% of cases.

Almost all children are remarkably short and have growth delay. Fever is extremely common but inconstant and is most often mild. Anemia is frequent. Other findings that have been reported include macrocephaly (95%), large fontanelle, prominent forehead, flattening of the nasal bridge (saddleback nose), short and thick extremities, and finger clubbing. The liver and/or spleen may be enlarged. Lymph node enlargement may also be present.

Later in life, secondary amyloidosis may occur. Delayed puberty and secondary amenorrhoea are not uncommon. Hoarseness due to inflammation of the laryngeal cartilage has also been reported.

Diagnosis is often confirmed by several abnormalities of skeletal origin. There is a sequential order of findings, according to Cormode et al., which initiate in abnormal cartilage calcification and later brachytelephalangism. The uniqueness of brachytelephalangy in KS results in distinctively broadened and shortened first through fourth distal phalanges, while the fifth distal phalanx bone remains unaffected. Radiography also reveals several skeletal anomalies including facial hypoplasia resulting in underdevelopment of the nasal bridge with noticeably diminished alae nasi. In addition to distinguishable facial features, patients generally demonstrate shorter than average stature and general mild developmental delay.

The differential diagnosis of broad thumbs includes Rubinstein-taybi syndrome, where they are a cardinal feature. FHS is also in the differential, which logically agrees with the thought that the disease is a result of a mutation in SRCAP, as this gene interacts with CBP.

Ischiopatellar dysplasia is a rare autosomal dominant disorder characterized by a hypoplasia of the patellae as well as other bone anomalies, especially concerning the pelvis and feet.

Mandibuloacral dysplasia is a rare autosomal recessive syndrome characterized by mandibular hypoplasia, delayed cranial suture closure, dysplastic clavicles, abbreviated and club-shaped terminal phalanges, acroosteolysis, atrophy of the skin of the hands and feet, and typical facial changes.

Types include:

The common symptoms in all reported cases of primrose syndrome include ossified pinnae, learning disabilities or mental retardation, hearing problems, movement disorders (ataxia, paralysis, and parkinsonism among others (likely due, in part, to calcification of the basal ganglia), a torus palatinus (a neoplasm on the mouth's hard palate), muscle atrophy, and distorted facial features. Other symptoms usually occur, different in each case, but it is unknown whether or not these symptoms are caused by the same disease.

Crouzon syndrome is an autosomal dominant genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial (or pharyngeal) arch, which is the precursor of the maxilla and mandible. Since the branchial arches are important developmental features in a growing embryo, disturbances in their development create lasting and widespread effects.

This syndrome is named after Octave Crouzon, a French physician who first described this disorder. He noted the affected patients were a mother and her daughter, implying a genetic basis. First called "craniofacial dysostosis", the disorder was characterized by a number of clinical features. This syndrome is caused by a mutation in the fibroblast growth factor receptor II, located on chromosome 10.

Breaking down the name, "craniofacial" refers to the skull and face, and "dysostosis" refers to malformation of bone.

Now known as Crouzon syndrome, the characteristics can be described by the rudimentary meanings of its former name. What occurs is that an infant's skull and facial bones, while in development, fuse early or are unable to expand. Thus, normal bone growth cannot occur. Fusion of different sutures leads to different patterns of growth of the skull.

Examples include: 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), Kleeblattschaedel (premature closure of all sutures).