The classical triad of symptoms that defines 3C syndrome includes certain heart defects, hypoplasia (underdevelopment) of the cerebellum, and cranial dysmorphisms, which can take various forms. The heart defects and cranial dysmorphisms are heterogeneous in individuals who are all classed as having Ritscher-Schinzel syndrome.

Heart defects commonly seen with Ritscher-Schinzel syndrome are associated with the endocardial cushion and are the most important factor in determining a diagnosis. The mitral valve and tricuspid valve of the heart can be malformed, the atrioventricular canal can be complete instead of developing into the interatrial septum and interventricular septum, and conotruncal heart defects, which include tetralogy of Fallot, double outlet right ventricle, transposition of the great vessels, and hypoplastic left heart syndrome. Aortic stenosis and pulmonary stenosis have also been associated with 3C syndrome.

The cranial dysmorphisms associated with 3C syndrome are heterogeneous and include a degree of macrocephaly, a large anterior fontanel, a particularly prominent occiput and forehead, ocular hypertelorism (wide-set eyes), slanted palpebral fissures, cleft palate, a depressed nasal bridge, cleft palate with associated bifid uvula, low-set ears, micrognathia (an abnormally small jaw), brachycephaly (flattened head), and ocular coloboma. Low-set ears are the most common cranial dysmorphism seen in 3C syndrome, and ocular coloboma is the least common of the non-concurrent symptoms (cleft lip co-occurring with cleft palate is the least common).

Cranial dysplasias associated with 3C syndrome are also reflected in the brain. Besides the cerebellar hypoplasia, cysts are commonly found in the posterior cranial fossa, the ventricles and the cisterna magna are dilated/enlarged, and Dandy-Walker malformation is present. These are reflected in the developmental delays typical of the disease. 75% of children with 3C syndrome have Dandy-Walker malformation and hydrocephalus.

Signs and symptoms in other body systems are also associated with 3C syndrome. In the skeletal system, ribs may be absent, and hemivertebrae, syndactyly (fusion of fingers together), and clinodactyly (curvature of the fifth finger) may be present. In the GI and genitourinary systems, anal atresia, hypospadia (misplaced urethra), and hydronephrosis may exist. Adrenal hypoplasia and growth hormone deficiency are associated endocrine consequences of Ritscher-Schinzel syndrome. Some immunodeficiency has also been reported in connection with 3C syndrome.

Many children with the disorder die as infants due to severe congenital heart disease. The proband of Ritscher and Schinzel's original study was still alive at the age of 21.

A fetus with 3C syndrome may have an umbilical cord with one umbilical artery instead of two.

Neonatal complications (apart from congenital anomalies) are common. In a paper published in 2010, 41 of 42 individuals had some type medical problem in the first days of life, the most common being feeding difficulties. Respiratory difficulty and jaundice are also relatively frequent.

The most common gastrointestinal abnormality is chronic constipation, though gastrointestinal reflux was also common.

3C syndrome, also known as CCC dysplasia, Craniocerebellocardiac dysplasia or Ritscher–Schinzel syndrome, is a rare condition, whose symptoms include heart defects, cerebellar hypoplasia, and cranial dysmorphism. It was first described in the medical literature in 1987 by Ritscher and Schinzel, for whom the disorder is sometimes named.

The three most common symptoms of Opitz G/BBB syndrome (both type I & II) are hypertelorism (exceptionally wide-spaced eyes), laryngo-tracheo-esophalgeal defects (including clefts and holes in the palate, larynx, trachea and esophagus) and hypospadias (urinary openings in males not at the tip of the penis) (Meroni, Opitz G/BBB syndrome, 2012). Abnormalities in the larynx, trachea and esophagus can cause significant difficulty breathing and/or swallowing and can result in reoccurring pneumonia and life-threatening situations. Commonly, there may be a gap between the trachea and esophagus, referred to as a laryngeal cleft; which can allow food or fluid to enter the airway and make breathing and eating a difficult task.

Genital abnormalities like a urinary opening under the penis (hypospadias), undescended testes (cryptorchidism), underdeveloped scrotum and a scrotum divided into two lobes (bifid scrotum) can all be commonplace for males with the disease.

Developmental delays of the brain and nervous system are also common in both types I and II of the disease. 50% of people with Opitz G/BBB Syndrome will experience developmental delay and mild intellectual disability. This can impact motor skills, speech and learning capabilities. Some of these instances are likened to autistic spectrum disorders. Close to half of the people with Opitz G/BBB Syndrome also have a cleft lip (hole in the lip opening) and possibly a cleft palate (hole in the roof of the mouth), as well. Less than half of the people diagnosed have heart defects, imperforate anus (obstructed anal opening), and brain defects. Of all the impairments, female carriers of X-linked Type I Opitz G/BBB Syndrome usually only have ocular hypertelorism.

Children with the Sanjad Sakati syndrome have a triad of:

a) hypoparathyroidism (with episodes of hypocalcemia, hypocalcemic tetany and hypocalcemic seizures.

b) severe mental retardation and

c) dysmorphism.

Typically, children with this syndrome are born low-birth-weight due to intrauterine growth retardation. At birth, there is dysmorphism, which is later typified into the features described below. The child is stunted, often with demonstrable growth hormone deficiency and has moderate to severe mental retardation, mainly as a consequence of repeated seizures brought on by the low blood ionic calcium levels. The immuno-reactive parathormone levels are low to undetectable, with low calcium and high phosphate levels in the blood.

"Dysmorphism" is most evident on the face, with the following features:

- Long narrow face

- Deep-set, small eyes

- Beaked nose

- Large, floppy ears

- Small head (microcephaly) and

- Thin lips with a long philtrum.

Cardiac defects are similar to those associated with Marfan's syndrome, a disorder of the connective tissue.

- Elongation of aorta

- Bicuspid aortic valve

- Subaortic stenosis

- Mitral valve prolapse with mitral regurgitation

- Atrial septal defect

- Patent ductus arteriosus

- Tricuspid valve prolapse

- Aortic dissection and aneurysm

- Aneurysm of ductus arteriosus

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.

Hemangiomas associated with PHACE Syndrome are usually small or not visible at birth, but are easier to see during the first days to weeks of life. They can grow rapidly. Hemangiomas linked with PHACE Syndrome tend to cover a large area of the face, head or neck, either as one lesion or as many single lesions.

Malpuech syndrome is congenital, being apparent at birth. It is characterized by a feature known as facial clefting. Observed and noted in the initial description of the syndrome as a cleft lip and palate, facial clefting is identified by clefts in the bones, muscles and tissues of the face, including the lips and palate. The forms of cleft lip and palate typically seen with Malpuech syndrome are midline (down the middle of the lip and palate) or bilateral (affecting both sides of the mouth and palate). Facial clefting generally encompasses a wide range of severity, ranging from minor anomalies such as a (split) uvula, to a cleft lip and palate, to major developmental and structural defects of the facial bones and soft tissues. Clefting of the lip and palate occurs during embryogenesis. Additional facial and ortho-dental anomalies that have been described with the syndrome include: hypertelorism (unusually wide-set eyes, sometimes reported as telecanthus), narrow palpebral fissures (the separation between the upper and lower eyelids) and ptosis (drooping) of the eyelids, frontal bossing (prominent eyebrow ridge) with synophris, highly arched eyebrows, wide nasal root and a flattened nasal tip, malar hypoplasia (underdeveloped upper cheek bone), micrognathia (an undersized lower jaw), and prominent incisors. Auditory anomalies include an enlarged ear ridge, and hearing impairment associated with congenital otitis media (or "glue ear", inflammation of the middle ear) and sensorineural hearing loss.

Another feature identified with Malpuech syndrome is a caudal appendage. A caudal appendage is a congenital outgrowth stemming from the coccyx (tailbone). Present in many non-human animal species as a typical tail, this feature when seen in an infant has been described as a "human tail". This was observed by Guion-Almeida (1995) in three individuals from Brazil. The appendage on X-rays variously appeared as a prominent protrusion of the coccyx. On a physical examination, the appendage resembles a nodule-like stub of an animal tail.

Deficiencies such as mental retardation, learning disability, growth retardation and developmental delay are common. Psychiatric manifestations that have been reported with the syndrome include psychotic behavior, obsessive–compulsive disorder, loss of inhibition, hyperactivity, aggression, fear of physical contact, and compulsive actions like echolalia (repeating the words spoken by another person). Neuromuscular tics have also been noted.

Urogenital abnormalities, or those affecting the urinary and reproductive systems, are common with the syndrome. Malpuech et al. (1983) and Kerstjens-Frederikse et al. (2005) reported variously in affected males a micropenis, hypospadias (a congenital mislocation of the urinary meatus), cryptorchidism ( or undescended testes), bifid (split) and underdeveloped scrotum, and an obstructive urethral valve. An affected boy was also reported by Reardon et al. (2001) with left renal agenesis, an enlarged and downwardly displaced right kidney, cryptorchidism and a shawl scrotum. Other malformations that have been noted with the syndrome are omphalocele and an umbilical hernia.

Congenital abnormalities of the heart have also been observed with Malpuech syndrome. From a healthy Japanese couple, Chinen and Naritomi (1995) described the sixth child who had features consistent with the disorder. This two-month-old male infant was also affected by cardiac anomalies including patent ductus arteriosus (PDA) and ventricular septal defect. The opening in the ductus arteriosus associated with PDA had been surgically repaired in the infant at 38 days of age. A number of minor skeletal aberrations were also reported in the infant, including wormian bones at the lambdoid sutures.

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.

Symptoms are related to defects in connective tissue.

- Congenital anterior dislocation of the knees

- Dislocation of hips and shoulders

- Flattened facial appearance

- Prominent forehead

- Depressed nasal bridge

- Club foot

- Cervical kyphosis

There is a wide range of congenital problems associated with kabuki syndrome with large differences between affected individuals. Some of the common problems are heart defects, urinary tract anomalies, hearing loss, hypotonia, recurrent ear infections and postnatal growth deficiency. Other characteristics include skeletal abnormality, joint laxity, short stature, and unusual dermatoglyphic patterns.

In terms of development, mild to moderate intellectual disability is a common feature. Also, children with kabuki syndrome often have distinctive behavioral features. A few have normal intelligence, most of whom have learning difficulties such as struggling with fine motor, speech skills, and memory.

There is no indication that the life expectancy of individuals with kabuki syndrome is shortened. Most medical issues are resolved with medical intervention. The fact that there are relatively few adults known with this syndrome is probably related to its recent discovery in 1980 in Japan and around 1990 in Europe and America.

This syndrome is characterised by typical facial appearance, slight build, thin and translucent skin, severely adducted thumbs, arachnodactyly, club feet, joint instability, facial clefting and bleeding disorders, as well as heart, kidney or intestinal defects. Severe psychomotor and developmental delay and decreased muscle tone may also be present during infancy. Cognitive development during childhood is normal.

Genitopatellar syndrome is a rare condition characterized by genital abnormalities, missing or underdeveloped kneecaps (patellae), intellectual disability, and abnormalities affecting other parts of the body.

Genitopatellar syndrome is also associated with delayed development and intellectual disability, which are often severe. Affected individuals may have an unusually small head (microcephaly) and structural brain abnormalities, including underdeveloped or absent tissue connecting the left and right halves of the brain (agenesis of the corpus callosum).

Almost all patients with this syndrome have some degree of mental retardation and facial dysmorphism (round face, deep-set eyes, thin upper lip). Behavioural problems are common. Brachymetaphalangism (metacarpal or metatarsal shortening) is reported in ~50% of cases overall, but is typically not evident below the age of 2 years. There is striking phenotypic variability, and the size and extent of the deleted region cannot be used as accurate predictors of prognosis. Some patients have additional problems such as congenital heart disease and seizures.

Approximately 100 cases have been described in the literature to date.

The facial features are characteristic and include

- Deep set eyes

- Strabismus

- Myopia

- Marked nasal root

- Broad and/or beaked nasal bridge

- Prominent Cupid's bow

- Everted lower lip

- Tented upper lip

- Large mouth

- Widely spaced teeth

- Wide and shallow palate

- Ears with thick and overfolded helix

Most have a smiling appearance.

Intellectual disability is severe. Language is absent or limited to only a few words. Stereotypic movements particularly of the arms, wrists and fingers is almost universal. Hypotonia is common (75%) as is an unsteady gait. All have delayed walking. Other features include a single (simian) palmar crease, long, slender fingers, flat feet and cryptorchidism (in males). Finger clubbing and the presence of fetal pads is common. Hyperventilation occurs in over half and is frequently followed by apnea and cyanosis. During these episodes aerophagia may occur. Constipation is common. Microcephaly and seizures may occur. Hypopigmented skin macules have occasionally been reported.

Two key features of AOS are aplasia cutis congenita with or without underlying bony defects and terminal transverse limb defects. Cutis aplasia congenita is defined as missing skin over any area of the body at birth; in AOS skin aplasia occurs at the vertex of the skull. The size of the lesion is variable and may range from solitary round hairless patches to complete exposure of the cranial contents. There are also varying degrees of terminal limb defects (for example, shortened digits) of the upper extremities, lower extremities, or both. Individuals with AOS may have mild growth deficiency, with height in the low-normal percentiles. The skin is frequently observed to have a mottled appearance (cutis marmorata telangiectatica congenita). Other congenital anomalies, including cardiovascular malformations, cleft lip and/or palate, abnormal renal system, and neurologic disorders manifesting as seizure disorders and developmental delay are sometimes observed. Variable defects in blood vessels have been described, including hypoplastic aortic arch, middle cerebral artery, pulmonary arteries. Other vascular abnormalities described in AOS include absent portal vein, portal sclerosis, arteriovenous malformations, abnormal umbilical veins, and dilated renal veins.

Other features include:

- Stunting

- Small hands and feet with long, tapering fingers and clinodactyly

- Dental anomalies in the form of malalignment and malocclusion

In another study of six patients, the patients were investigated further. They were found to have low levels of IGF-1 and markedly retarded bone age.

The facial appearance of individuals with this syndrome include long eyelids with turning up of the lateral third of the lower eyelid, a broad and depressed nasal tip, large prominent earlobes, and a cleft or high-arched palate.

Other clinical features often include scoliosis, short fifth finger, persistence of fingerpads, and X-ray abnormalities of the vertebrae, hands, and hip joints.

Symptoms vary, but usually result in dysmorphisms in the skull, nervous system, and developmental delay. Dysmorphisms in the heart, kidneys, and musculoskeletal system may also occur. An infant with complete trisomy 9 surviving 20 days after birth showed clinical features including a small face, wide fontanelle, prominent occiput, micrognathia, low set ears, upslanting palpebral fissures, high-arched palate, short sternum, overlapping fingers, limited hip abduction, rocker bottom feet, heart murmurs and also a webbed neck.

Trisomy 9p is one of the most frequent autosomal anomalies compatible with long survival rate. A study of five cases showed an association with Coffin–Siris syndrome, as well as a wide gap between the first and second toes in all five, while three had brain malformations including dilated ventricles with hypogenesis of the corpus callosum and Dandy-Walker malformation.

As it grows, the hemangioma can break down skin, distort facial features or get in the way of other vital functions, such as breathing, vision, and hearing. Other complications will depend on what other structures are involved. These could include developmental delay, seizures, headaches, and abnormal muscle tone if the brain is involved.

FG syndrome's major clinical features include intellectual disability, usually severe; hyperactive behavior, often with an outgoing personality; severe constipation, with or without structural anomalies in the anus such as imperforate anus; macrocephaly; severe hypotonia; a characteristic facial appearance due to hypotonia, giving a droopy, "open-mouthed" expression, a thin upper lip, a full or pouting lower lip, and partial or complete loss of the corpus callosum. About a third of reported cases of individuals with FG syndrome die in infancy, usually due to respiratory infection; premature death is rare after infancy.

Following are the features and characteristics that help in spotting this disorder:

- Low birth weight (usually under 5 pounds/2.5 kilograms)

- Delayed growth and small stature

- Developmental delay

- Limb differences (missing limbs or portions of limbs)

- Small head size (microcephaly)

- Thick eyebrows, which typically meet at midline (synophrys)

- Long eyelashes

- Short upturned nose and thin downturned lips

- Long philtrum

- Excessive body hair

- Small hands and feet

- Small widely spaced teeth

- Low-set ears

- Hearing impairments

- Vision abnormalities (e.g., ptosis, nystagmus, high myopia, hypertropia)

- Partial joining of the second and third toes

- Incurved 5th fingers (clinodactyly)

- Gastroesophageal reflux

- Seizures

- Heart defects (e.g., pulmonary stenosis, VSD, ASD, coarctation of the aorta)

- Cleft palate

- Feeding problems

- Hypoplastic genitalia

Children with this syndrome are often found to have long eyelashes, bushy eyebrows and synophrys (joined eyebrows). Body hair can be excessive and affected individuals are often shorter than their immediate family members. They present a characteristic facial phenotype and is recognizable with the Facial Dysmorphology Novel Analysis (FDNA) technology

CdLS can give rise to its own array of complexities. Children with CdLS often suffer from gastrointestinal tract difficulties, particularly gastroesophageal reflux. Vomiting, intermittent poor appetite, constipation, diarrhea or gaseous distention are known to be a regularity in cases where the GI tract problems are acute. Symptoms may range from mild to severe.

CdLS may include behavior problems, including self-stimulation, aggression, self-injury or strong preference to a structured routine. Many children with CdLS exhibit autistic-like behaviors.

Behavior problems in CdLS are not inevitable. Many behavior issues associated with CdLS are reactive (i.e., something happens within the person's body or environment to bring on the behavior) and cyclical (comes and goes). Often, an underlying medical issue causes a change in behavior. Once the medical issue is treated, the behavior diminishes.

The most common symptoms of Nicolaides–Baraitser syndrome are mild to severe developmental delays with absent or limited speech, seizures, short stature, sparse hair, typical facial characteristics, brachydactyly, and prominent finger joints and broad distal phalanges.