Children with Weaver syndrome tend to look similar and have distinctive physical and craniofacial characteristics, which may include several, but not all of the following features:

- Macrocephaly

- Large bifrontal diameter

- Flattened occiput

- Long philtrum

- Retrognathia

- Round face in infancy

- Prominent chin crease

- Large ears

- Strabismus

- Hypertelorism

- Epicanthal folds

- Downslanting palpebral fissures

Other features may include loose skin, thin deep-set nails, thin hair, short ribs, limited elbow and knee extension, camptodactyly, and a coarse, low-pitched voice. Delayed development of motor skills such as sitting, standing, and walking are commonly exhibited in early childhood. Patients with Weaver syndrome typically have mild intellectual disability with poor coordination and balance. They also have some neurological abnormalities such as speech delay, epilepsy, intellectual disability, hypotonia or hypertonia, and behavioral problems.

ATR-16 syndrome affects the blood, development, and brain; symptoms vary based on the specific genes deleted on chromosome 16. Because it is so rare, it is difficult to determine the "core" symptoms of the disease. People with ATR-16 have alpha-thalassemia, a blood disorder where there is less normal hemoglobin in the blood than there should be, and the red blood cells are smaller than they should be (microcytic anemia). Affected children have various characteristic physical features, including clubfoot, "locked" little fingers, microcephaly (small head), hypertelorism (widely spaced eyes), broad, prominent nose bridge, downward-slanted palpebral fissures, small ears, retrognathia, and short neck. Children with ATR-16 syndrome also have mild to moderate intellectual disabilities, developmental delays/growth delays, and speech delays. Some children with ATR-16 have seizures, cryptorchidism (undescended testes), or hypospadias.

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.

GMS syndrome is a syndrome characterised by goniodysgenesis, intellectual disability, and short stature.

Associated with agenesis (loss) of the corpus callosum, intellectual disabilities are common among individuals with FG syndrome. Motor ability is also impaired as a result of having FG syndrome and its effects on the development of neurons. During infancy, problems arise in the gastrointestinal and gastroesophageal systems of the body. The most common gastrointestinal problems include constipation from imperforated anuses and gastroesophageal reflux. Cardiopulmonary defects also contribute to roughly 60% of premature deaths in infants with FG syndrome. Of all of the congenital heart defects septal defects are the most common. After infancy, long term survival has been recorded to individuals surviving beyond the age of 50.

People with Renpenning's typically begin learning language at an ordinary pace, but by the age of 3–4 they experience a regression in mental and physical development, such as mild low muscle tone resulting in elongated faces and rapid loss in the normal growth of the head (microcephaly). Small testes and short stature are also known to commonly occur.

Micro syndrome can be identified in people several ways, one of the most common is ocular problems or other physical traits that don't appear natural. It is especially easy to identify micro syndrome in infants and in younger children. Intellectual or developmental disabilities can seriously affect a patient in the way they think and move. So far according to studies all patients have had serious intellectual or developmental disabilities, and hypotonia is found in all the patients during infancy.

Aneuploidy is often fatal, but in this case there is "X-inactivation" where the effect of the additional gene dosage due to the presence of extra X chromosomes is greatly reduced.

Much like Down syndrome, the mental effects of 49,XXXXY syndrome vary. Impaired speech and behavioral problems are typical. Those with 49,XXXXY syndrome tend to exhibit infantile secondary sex characteristics with sterility in adulthood and have some skeletal anomalies. Skeletal anomalies include:

- Genu valgum

- Pes cavus

- Fifth finger clinodactyly

The effects also include:

- Cleft palate

- Club feet

- Respiratory conditions

- Short or/and broad neck

- Low birth weight

- Hyperextensible joints

- Short stature

- Narrow shoulders

- Coarse features in older age

- Hypertelorism

- Epicanthal folds

- Prognathism

- Gynecomastia (rare)

- Muscular hypotonia

- Hypoplastic genitalia

- Cryptorchidism

- Congenital heart defects

- A very round face in infancy

Associated symptoms range from things such as colobomas of the eyes, heart defects, ichthyosiform dermatosis, intellectual disability, and ear abnormalities. Further symptoms that may be suggested include characteristic facies, hearing loss, and cleft palate.

Symptoms of M2DS include infantile hypotonia and failure to thrive, delayed psychomotor development, impaired speech, abnormal or absent gait, epilepsy, spasticity, gastrointestinal motility problems, recurrent infections, and genitourinary abnormalities. Many of those affected by M2DS also fit diagnostic criteria for autism. M2DS can be associated with syndromic facies, namely an abnormally flat back of the head, underdevelopment of the midface, ear anomalies, deep-set eyes, prominent chin, pointed nose, and a flat nasal bridge.

This autosomal dominant disorder is characterized by a number of health defects including Hirschsprung's disease, intellectual disability, epilepsy, delayed growth and motor development, congenital heart disease, genitourinary anomalies and absence of the corpus callosum. However, Hirschsprung's disease is not present in all infants with Mowat–Wilson syndrome and therefore it is not a required diagnostic criterion. Distinctive physical features include microcephaly, narrow chin, cupped ears with uplifted lobes with central depression, deep and widely set eyes, open mouth, wide nasal bridge and a shortened philtrum.

Infants with Emanuel syndrome have weak muscle tone (hypotonia) and fail to gain weight and grow at the expected rate (failure to thrive). Their development is significantly delayed, and most affected individuals have severe to profound intellectual disability. Other features of Emanuel syndrome include an unusually small head (microcephaly), distinctive facial features, and a small lower jaw (micrognathia). Ear abnormalities are common, including small holes in the skin just in front of the ears (preauricular pits or sinuses). About half of all affected infants are born with an opening in the roof of the mouth (cleft palate) or a high arched palate. Males with Emanuel syndrome often have genital abnormalities. Additional signs of this condition can include heart defects and absent or unusually small (hypoplastic) kidneys; these problems can be life-threatening in infancy or childhood.

There are many signs and symptoms of Prader–Willi syndrome. The symptoms can range from poor muscle tone during infancy to behavioral problems in early childhood. Some symptoms that are usually found in infants, besides poor muscle tone, would be a lack of eye coordination; some are born with almond-shaped eyes; and due to poor muscle tone the infant may not have a strong sucking reflex. Their cry is weak, and they have difficulty waking up. Another sign of this condition is a thin upper lip.

More aspects seen in a clinical overview include hypotonia and abnormal neurologic function, hypogonadism, developmental and cognitive delays, hyperphagia and obesity, short stature, and behavioral and psychiatric disturbances.

Holm "et al." (1993) describe the following features and signs as pretest indicators of PWS, although not all will be present.

Almost all children with Jacobsen syndrome have Intellectual disabilities, which ranges from mild to moderate depending upon the number of the deletion of genes from the chromosome. Children with intellectual disability take more time than normal to learn new things and acquire new skills. They have problems with assembling new information or adapting to novel situations and associating two events or things together.

Most kids with the syndrome have delayed development including delayed speech, motor disabilities, lack of coordination, which makes even simple activities like sitting, standing and walking difficult for these children. Most kids eventually start speaking but in cases with severe intellectual disability language use is highly restricted.

They have distinctive facial features like:

- Small head (microcephaly)

- Pointed forehead, (trigonocephaly)

- Small ears which are low-set

- Widely-spaced eyes (hypertelorism)

- Droopy eyelids (ptosis)

- Broad nasal bridge

- Abnormally thin upper lips

- Downturned corners of the mouth

- Excess skin covering in the inner corner of eyes (epicanthal folds)

Some children also suffer from behavioural problems like distractibility, hyperactivity, impaired communication and social skills which qualifies them for a diagnosis of ASD and ADHD.

Heart defects are very common in children with Jacobsen Syndrome. 88.5% of people with the disorder have Paris-Trousseau syndrome which is a bleeding disorder and causes a lifelong risk of abnormal bleeding and bruising due to dysfunction in the platelets.

Other symptoms may include eye problems, ear and sinus infections, hearing problems, bone deformities, growth hormone deficiency, gastrointestinal problems, kidney malfunctions etc.

The combination of muscular hypotonia and fixed dilated pupils in infancy is suspicious of Gillespie syndrome. Early onset partial aniridia, cerebellar ataxia, and mental retardation are hallmark of syndrome. The iris abnormality is specific and seems pathognomonic of Gillespie syndrome. The aniridia consisting of a superior coloboma and inferior iris hypoplasia, foveomacular dysplasia.

Atypical Gillespie syndrome associated with bilateral ptosis, exotropia, correctopia, iris hypoplasia, anterior capsular lens opacities, foveal hypoplasia, retinal vascular tortuosity, and retinal hypopigmentation.

Neurological signs ar nystagmus, mild craniofacial asymmetry, axial hypotonia, developmental delay, and mild mental retardation. Mariën P did not support the prevailing view of a global mental retardation as a cardinal feature of Gillespie syndrome but primarily reflect cerebellar induced neurobehavioral dysfunctions following disruption of the cerebrocerebellar anatomical circuitry that closely resembles the "cerebellar cognitive and affective syndrome" (CeCAS).

Congenital pulmonary stenosis and helix dysplasia can be associated.

LFS is clinically distinguished from other X-linked forms of intellectual disability by the accompanying presence of marfanoid habitus. Marfanoid habitus describes a group of physical features common to Marfan syndrome. Including Marfan syndrome and LFS, marfanoid features of this type have also been observed with several other disorders, one of which is multiple endocrine neoplasia type 2.

In LFS, specific features identified as marfanoid include: a long, narrow face; tall, thin stature; long, slender limbs, fingers and toes (not unlike arachnodactyly) with joint hyperextensibility, shortened halluces (the big toes) and long second toes.

The diagnosis of marfanoid habitus in LFS is often delayed because many of the physical features and characteristics associated with it are usually not evident until adolescence.

Weaver syndrome (also called Weaver-Smith syndrome) is an extremely rare congenital disorder associated with rapid growth beginning in the prenatal period and continuing through the toddler and youth years. It is characterized by advanced osseous maturation, and distinctive craniofacial, skeletal, and neurological abnormalities. It was first described by Dr. David Weaver in 1974. It is similar to Sotos syndrome.

Micro syndrome also known as WARBM, and Warburg–Sjo–Fledelius syndrome, is a rare autosomal recessive genetic disorder characterized by microcephaly, microcornea, congenital cataract, intellectual or developmental disability, optic atrophy, and hypogenitalism.

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).

Psychopathology and related behavioral abnormalities are typically seen in LFS, and they may be considered in the diagnosis of the disorder. The most common of these in LFS is an autism-like spectrum disorder, and LFS is considered as one of a number of genetic disorders associated with autism. Additional alterations of psychopathology with behavioral manifestations that have been observed in LFS include: psychotic behavior, schizophrenia, hyperactivity and attention-deficit hyperactivity disorder, aggression, oppositional defiant disorder, obsessive compulsive disorder, extreme shyness, learning disability, cognitive impairment, short-term memory deficit, low frustration tolerance, social dysfunction, lack of impulse control, eating disorder and associated malnutrition, attributed to psychogenic loss of appetite; and pyromania.

While psychiatric conditions like these are to be expected with LFS, there have also been cases of the disorder with some preservation of mental and behavioral abilities, such as problem solving, reasoning and normal intelligence.

The psychopathology of LFS usually exhibits schizophrenia. When schizophrenia is diagnosed in an individual known to be affected by intellectual disability, LFS may be considered in the differential diagnosis of schizophrenia, with confirmation of cause through appropriate psychiatric and genetic evaluation methods.

ATR-16 syndrome, also called Alpha-Thalassemia-Intellectual disability syndrome is a rare disease characterized by monosomy on part of chromosome 16.

Individuals with PWS are at risk of learning and attention difficulties. Curfs and Fryns (1992) conducted research into the varying degrees of learning disability found in PWS. Their results, using a measure of IQ, were as follows:

- 5%: IQ above 85 (high to low average intelligence)

- 27%: IQ 70–85 (borderline intellectual functioning)

- 39%: IQ 50–70 (mild intellectual disability)

- 27%: IQ 35–50 (moderate intellectual disability)

- 1%: IQ 20–35 (severe intellectual disability)

- <1%: IQ <20 (profound intellectual disability)

Cassidy found that 40% of individuals with PWS have borderline/low average intelligence, a figure higher than the 32% found in Curfs and Fryns' study. However, both studies suggest that most individuals (50–65%) fall within the mild/borderline/low average intelligence range.

Children with PWS show an unusual cognitive profile. They are often strong in visual organization and perception, including reading and vocabulary, but their spoken language (sometimes affected by hypernasality) is generally poorer than their comprehension. A marked skill in completing jigsaw puzzles has been noted, but this may be an effect of increased practice.

Auditory information processing and sequential processing are relatively poor, as are arithmetic and writing skills, visual and auditory short-term memory and auditory attention span. These sometimes improve with age, but deficits in these areas remain throughout adulthood.

There may be an association with psychosis.

The symptoms and prognosis of tetrasomy 9p are highly variable. The severity of the symptoms is largely determined by the size of the isochromosome, the specific regions of chromosome 9p that are duplicated, as well as the number and type of tissues that are affected in the mosaic form.

Most patients exhibit some degree of intellectual disability, abnormal skeletal and muscular development, and abnormal facial structures. Cognitive symptoms range from slight learning disabilities to severe deficits in intellectual functioning. Due to abnormal development of the muscles, individuals often experience limited or delayed mobility. Atypical facial features are characteristic of the syndrome, including widely spaced eyes, a large nose, and unusually positioned ears. Additionally, patients often have extra skin around the neck and widely spaced nipples. A wide range of renal, digestive, cardiac, respiratory, and nervous system abnormalities have been observed.

Though rare, a few cases of phenotypically normal individuals with tetrasomy 9p have been documented.

The signs and symptoms of Kaufman oculocerebrofacial syndrome are consistent with the following:

- High palate

- Microcephaly

- Constipation

- Intellectual disability

- Muscular hypotonia

- Nystagmus

Children with 1p36 deletion syndrome are all unique individuals, but do have some common distinct facial features such as: