It is characterized by variable reductions in serum immunoglobulin levels which cause most ICF patients to succumb to infectious diseases before adulthood. ICF syndrome patients exhibit facial anomalies which include hypertelorism, low-set ears, epicanthal folds and macroglossia.

It is characterized by developmental defects including cryptophthalmos (where the eyelids fail to separate in each eye), and malformations in the genitals (such as micropenis, cryptorchidism or clitoromegaly). Congenital malformations of the nose, ears, larynx and renal system, as well as mental retardation, manifest occasionally. Syndactyly (fused fingers or toes) has also been noted.

ICF syndrome (or Immunodeficiency, Centromere instability and Facial anomalies syndrome) is a very rare autosomal recessive immune disorder.

An alternative name of the condition, LEOPARD syndrome, is a mnemonic, originally coined in 1969, as the condition is characterized by some of the following seven conditions, the first letters of which spell LEOPARD, along with the characteristic "freckling" of the skin, caused by the lentigines that is reminiscent of the large cat.

- Lentigines — Reddish-brown to dark brown macules (surface skin lesion) generally occurring in a high number (10,000+) over a large portion of the skin, at times higher than 80% coverage. These can even appear inside the mouth (buccal), or on the surface of the eye (scleral). These have irregular borders and range in size from 1 mm in diameter to café-au-lait spots, several centimeters in diameter. Also, some areas of vitiligo-like hypopigmentation may be observed.

- Electrocardiographic conduction abnormalities: Generally observed on an electrocardiograph as a bundle branch block.

- Ocular hypertelorism: Wideset eyes, which lead to a similar facial resemblance between patients. Facial abnormalities are the second highest occurring symptom after the lentigines. Abnormalities also include: broad nasal root, prognathism (protruding lower jaw), or low-set, possibly rotated, ears.

- Pulmonary stenosis: Narrowing of the pulmonary artery as it exits the heart. Other cardiac abnormalities may be present, including aortic stenosis, or mitral valve prolapse.

- Abnormal genitalia: usually cryptorchidism (retention of testicles in body) or monorchism (single testicle). In female patients, this presents as missing or single ovaries, much harder by nature to detect. Ultrasound imaging is performed at regular intervals, from the age of 1 year, to determine if ovaries are present.

- Retarded growth: Slow, or stunted growth. Most newborns with this syndrome are of normal birth weight and length, but will often slow within the first year.

- Deafness: Sensorineural (nerve deafness).

The presence of all of these hallmarks is not needed for a diagnosis. A clinical diagnosis is considered made when, with lentigines present there are 2 other symptoms observed, such as ECG abnormalities and ocular hypertelorism, or without lentigines, 3 of the above conditions are present, with a first-degree relative (i.e. parent, child, sibling) with a clinical diagnosis.

- Additional dermatologic abnormalities (axillary freckling, localized hypopigmentation, interdigital webbing, hyperelastic skin)

- Mild mental retardation is observed in about 30% of those affected with the syndrome

- Nystagmus (involuntary eye movements), seizures, or hyposmia (reduced ability to smell) has been documented in a few patients

- In 2004, a patient was reported with recurrent upper extremity aneurysms that required surgical repairs.

- In 2006, a NSML patient was reported with acute myelogenous leukemia.

Due to the rarity of the syndrome itself, it is hard to determine whether certain additional diseases are actually part of the syndrome. With a base population of possibly less than one thousand individuals, one or two outlying cases can skew the statistical population very quickly.

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

Clinically, McKusick–Kaufman syndrome is characterized by a combination of three features: postaxial polydactyly, heart defects, and genital abnormalities:

- Vaginal atresia with hydrometrocolpos

- Double vagina and/or uterus.

- Hypospadias, chordee (a downward-curving penis), and undescended testes (cryptorchidism).

- ureter stenosis or ureteric atresia

Many of the characteristic facial features result from the premature fusion of the skull bones (craniosynostosis). The head is unable to grow normally, which leads to a high prominent forehead (turribrachycephaly), and eyes that appear to bulge (proptosis) and are wide-set (hypertelorism). In addition, there is an underdeveloped upper jaw (maxillary hypoplasia). About 50 percent of children with Pfeiffer syndrome have hearing loss, and dental problems are also common.

In people with Pfeiffer syndrome, the thumbs and first (big) toes are wide and bend away from the other digits (pollex varus and hallux varus). Unusually short fingers and toes (brachydactyly) are also common, and there may be some webbing or fusion between the digits (syndactyly).

All types of Griscelli syndrome have distinctive skin and hair coloring.

Type 1 is associated with eurological abnormalities. These include delayed development, intellectual disability, seizures, hypotonia and eye abnormalities.

Type 2 - unlike type 1 - is not associated primary neurological disease but is associated with an uncontrolled T lymphocyte expansion and macrophage activation syndrome. It is often associated with the hemophagocytic syndrome. This latter condition may be fatal in the absence of bone marrow transplantation.

Persons with type 3 have the typical light skin and hair coloring but are otherwise normal.

The RASopathies are developmental syndromes caused by germline mutations (or in rare cases by somatic mosaicism) in genes that alter the Ras subfamily and mitogen-activated protein kinases that control signal transduction, including:

- Capillary malformation-AV malformation syndrome

- Autoimmune lymphoproliferative syndrome

- Cardiofaciocutaneous syndrome

- Hereditary gingival fibromatosis type 1

- Neurofibromatosis type 1

- Noonan syndrome

- Costello syndrome, Noonan-like

- Legius syndrome, Noonan-like

- Noonan syndrome with multiple lentigines, formerly called LEOPARD syndrome, Noonan-like

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.

Orofaciodigital syndrome type 1 is diagnosed through genetic testing. Some symptoms of Orofaciodigital syndrome type 1 are oral features such as, split tongue, benign tumors on the tongue, cleft palate, hypodontia and other dental abnormalities. Other symptoms of the face include hypertelorism and micrognathia. Bodily abnormalities such as webbed, short, joined, or abnormally curved fingers and toes are also symptoms of Orofaciodigital syndrome type 1. The most frequent symptoms are accessory oral frenulum, broad alveolar ridges, frontal bossing, high palate, hypertelorism, lobulated tongue, median cleft lip, and wide nasal bridge. Genetic screening of the OFD1 gene is used to officially diagnose a patient who has the syndrome, this is detected in 85% of individuals who are suspected to have Orofaciodigital syndrome type 1.

Fraser syndrome (also known as Meyer-Schwickerath's syndrome, Fraser-François syndrome, or Ullrich-Feichtiger syndrome) is an autosomal recessive congenital disorder. Fraser syndrome is named for the geneticist George R. Fraser, who first described the syndrome in 1962.

Symptoms for Alström syndrome generally appear during infancy with great variability in age. Some of the symptoms include:

- Heart failure (Dilated cardiomyopathy) in over 60% of cases, usually within the first few weeks after birth, but sometimes the onset is in adolescence or adulthood.

- Light sensitivity and vision problems (Cone-rod dystrophy) in all cases, usually within 15 months of birth and progressively worsening until about 20 years of age

- Delays in early, developmental milestones in 50% of cases, learning disabilities in about 30% of cases

- Obesity in 100% of cases, apparent by 5 years of age, but often apparent in infancy (Alström infants usually have normal birth weights, and by adolescence, weights tend to be in the high-normal to normal range)

- Nystagmus (usually affects the children) one of the first symptoms to occur which causes involuntary rapid eye movement.

- Heart failure (Dilated cardiomyopathy) in over 60% of cases, usually within the first few weeks after birth, but sometimes the onset is in adolescence or adulthood.(chronic)

- Mild to moderate bilateral sensorineural hearing loss.

- Type 2 diabetes usually occurs in early childhood.

- Hyperinsulinemia/ insulin resistance—development of high level of insulin in blood.

- Steatosis (fatty liver) and elevated transaminases (liver enzymes) often develop in childhood and can progress in some patients to cirrhosis and liver failure.

- Endocrine dysfunctions may occur where the patient may experience an under or over active thyroid gland, weak growth hormone, increased androgen in females, and low testosterone in males.

- Slowly progressive kidney failure can occur in the second to fourth decade of life.

Chief markers of Goldenhar syndrome are incomplete development of the ear, nose, soft palate, lip, and mandible on usually one side of the body. Additionally, some patients will have growing issues with internal organs, especially heart, kidneys, and lungs. Typically, the organ will either not be present on one side or will be underdeveloped. Note that while it is more usual for there to be problems on only one side, it has been known for defects to occur bilaterally (approximate incidence 10% of confirmed GS cases).

Other problems can include severe scoliosis (twisting of the vertebrae), limbal dermoids, and hearing loss (see hearing loss with craniofacial syndromes), and deafness or blindness in one or both ears/eyes, Granulosa cell tumors may be associated as well.

McKusick–Kaufman syndrome is a genetic condition associated with MKKS.

The condition is named for Dr. Robert L. Kaufman and Victor McKusick. It is sometimes known by the abbreviation MKS. In infancy it can be difficult to distinguish between MKS and the related Bardet–Biedl syndrome, as the more severe symptoms of the latter condition rarely materialise before adulthood.

49,XXXXY syndrome is an extremely rare aneuploidic sex chromosomal abnormality. It occurs in approximately 1 out of 85,000 to 100,000 males.

Children with Pfeiffer syndrome types 2 and 3 "have a higher risk for neurodevelopmental disorders and a reduced life expectancy" than children with Pfeiffer syndrome type 1, but if treated, favorable outcomes are possible. In severe cases, respiratory and neurological complications often lead to early death.

FACES syndrome is a syndrome of unique facial features, anorexia, cachexia, eye and skin anomalies.

It is a rare disease and estimated to occur in less than 1 in 1 million people.

Noonan syndrome with multiple lentigines (NSML) which is part of a group called Ras/MAPK pathway syndromes, is a rare autosomal dominant, multisystem disease caused by a mutation in the protein tyrosine phosphatase, non-receptor type 11 gene ("PTPN11"). The disease is a complex of features, mostly involving the skin, skeletal and cardiovascular systems, which may or may not be present in all patients. The nature of how the mutation causes each of the condition's symptoms is not well known; however, research is ongoing. It is a RASopathy.

Noonan syndrome with multiple lentigines is caused by a different missense mutation of the same gene. Noonan syndrome is fairly common (1:1,000 to 1:2,500 live births), and neurofibromatosis 1 (which was once thought to be related to NSML) is also common (1:3500); however, no epidemiological data exists for NSML.

Recognised symptoms up till now are:

- Autism or autistic behaviors

- ADHD

- Learning disability

- Large head

- Dysmorphic facial appearance - mild

- Prominent forehead

- Wide-set eyes (hypertelorism)

- Schizophrenia

- Loose joints

- GERD

- Sleep disturbances

- Sleep Apnea

- Underdeveloped parts of brain - corpus callosum and cerebellar vermis

- Neuroblastoma

- Speech & developmental delays

- Chiari malformation of the brain

- Congenital heart defects

- Hypotonia

It is not clear whether the list of symptoms is complete. Very little information is known about the syndrome. The symptomology may be different among individuals, even in the same family.

Orofaciodigital syndrome 1 (OFD1), also called Papillon-League and Psaume syndrome, is an X-linked congenital disorder characterized by malformations of the face, oral cavity, and digits with polycystic kidney disease and variable involvement of the central nervous system.

1q21.1 duplication syndrome or 1q21.1 (recurrent) microduplication is a rare aberration of chromosome 1.

In a common situation a human cell has one pair of identical chromosomes on chromosome 1. With the 1q21.1 duplication syndrome one chromosome of the pair is over complete, because a part of the sequence of the chromosome is duplicated twice or more. In 1q21.1, the '1' stands for chromosome 1, the 'q' stands for the long arm of the chromosome and '21.1' stands for the part of the long arm in which the duplication is situated.

Next to the duplication syndrome, there is also a 1q21.1 deletion syndrome. While there are two or three copies of a similar part of the DNA on a particular spot with the duplication syndrome, there is a part of the DNA missing with the deletion syndrome on the same spot. Literature refers to both the deletion and the duplication as the 1q21.1 copy-number variations (CNV).

The CNV leads to a very variable phenotype and the manifestations in individuals are quite variable. Some people who have the syndrome can function in a normal way, while others have symptoms of mental retardation and various physical anomalies.

Recognised symptoms are:

- Only one set of genes on the two chromosomes function (Haploinsufficiency)

- Thrombocytopenia-absent radius (TAR syndrome), in case of a class II-deletion

- Neurological-psychiatric problems: Autism; schizophrenia; epilepsy; learning problems; cognitive disabilities — mild to moderate; developmental delay — mild to moderate (milestones like sitting, standing and walking; come at a later period in childhood); children show an ataxic gait and fall down a lot

- Dysmorphism: Slightly unusual facial appearance; disturbed growth; skeletal malformations; small head (microcephaly); prominent forehead; bulbous nose; deep-set eyes; broad thumbs; broad toes; squint; very flexible joints; clavicular pseudoarthrosis (the collarbone doesn't develop normally) (Class II-deletion); An extra transverse crease of the fifth finger (Class II-deletion)); Problems with the development of the vagina (Müllerian aplasia)

- Eyes: Cataracts

- Heart abnormalities and cardiovascular anomalies (30% of the cases): Anomalous origin of the coronary artery (Class II-deletion)

- Kidneys: Missing kidney or floating kidneys

- Cancer: Neuroblastoma

- Sleep disturbances

It is not clear whether the list of symptoms is complete. Very little information is known about the syndrome. The syndrome can have completely different effects on members of the same family.

A common deletion is between 1.0–1.9Mb. Mefford states that the standard for a deletion is 1.35Mb. The largest deletion seen on a living human is over 5 Mb.

Acrocephalosyndactylia (or acrocephalosyndactyly) is the common presentation of craniosynostosis and syndactyly.

The most striking sign of Timothy syndrome is the co-occurrence of both syndactyly (~0.03% of births) and long QT syndrome (1% per year) in a single patient. Other common symptoms of Timothy syndrome are cardiac arrhythmia (94%), heart malformations (59%), autism or an autism spectrum disorder (80% who survive long enough for evaluation). Facial dysmorphologies such as flattened noses also occur in approximately half of patients. Children with this disorder have small teeth which, due to poor enamel coating, are prone to dental cavities and often require removal. The average age of death due to complications of these symptoms is 2.5 years.

Atypical Timothy syndrome has largely the same symptoms as the classical form. Differences in the atypical form are the lack of syndactyly, the presence of musculoskeletal problems (particularly hyperflexible joints), and atrial fibrillation. Patients with atypical Timothy syndrome also have more facial deformities, including protruding foreheads and tongues. Finally, one patient with atypical Timothy syndrome had a body development discrepancy wherein her upper body was normally developed (that of a 6-year-old) while her lower half resembled a 2- or 3-year-old.

Children with Timothy syndrome tend to be born via caesarean section due to fetal distress.