Symptoms vary from one type of the syndrome to another and from one patient to another, but they include:

- Very pale or brilliantly blue eyes, eyes of two different colors (complete heterochromia), or eyes with one iris having two different colors (sectoral heterochromia)

- A forelock of white hair ("poliosis"), or premature graying of the hair

- Appearance of wide-set eyes due to a prominent, broad nasal root ("dystopia canthorum")—particularly associated with Type I) also known as "telecanthus"

- Moderate to profound hearing loss (higher frequency associated with Type II);

- A low hairline and eyebrows that meet in the middle ("synophrys")

- Patches of white skin pigmentation, in some cases

- Abnormalities of the arms, associated with Type III

- neurologic manifestations, associated with Type IV

- Cleft lip, mostly associated with Type I

Waardenburg syndrome has also been associated with a variety of other congenital disorders, such as intestinal and spinal defects, elevation of the scapula and cleft lip and palate. Sometimes this is concurrent with Hirschsprung disease.

Waardenburg syndrome is a rare genetic disorder most often characterized by varying degrees of deafness, minor defects in structures arising from the neural crest, and pigmentation changes. It was first described in 1951. The syndrome was later found to have four types. For example, type II was identified in 1971, to describe cases where dystopia canthorum was not present. Some types are now split into subtypes, based upon the gene responsible for the condition.

Paris syndrome (, , "Pari shōkōgun") is a transient mental disorder exhibited by some individuals when visiting or going on vacation to Paris, as a result of extreme shock derived from their discovery that Paris is not what they had expected it to be. The syndrome is characterized by a number of psychiatric symptoms such as acute delusional states, hallucinations, feelings of persecution (perceptions of being a victim of prejudice, aggression, or hostility from others), derealization, depersonalization, anxiety, and also psychosomatic manifestations such as dizziness, tachycardia, sweating, and others, such as vomiting. Similar syndromes include Jerusalem syndrome and Stendhal syndrome. The condition is commonly viewed as a severe form of culture shock. It is particularly noted among Japanese travelers.

Usher syndrome is responsible for the majority of deaf-blindness. The word "syndrome" means that multiple symptoms occur together, in this case, deafness and blindness. It occurs in roughly 1 person in 23,000 in the United States, 1 in 28,000 in Norway and 1 in 12,500 in Germany. People with Usher syndrome represent roughly one-sixth of people with retinitis pigmentosa.

Usher syndrome is inherited in an autosomal recessive pattern. "Recessive" means both parents must contribute an appropriate gene for the syndrome to appear, and "autosomal" means the gene is not carried on one of the sex chromosomes (X or Y), but rather on one of the 22 other pairs. (See the article on human genetics for more details.)

The progressive blindness of Usher syndrome results from retinitis pigmentosa. The photoreceptor cells usually start to degenerate from the outer to the center of the retina, including the macula. The degeneration is usually first noticed as night blindness (nyctalopia); peripheral vision is gradually lost, restricting the visual field (tunnel vision), which generally progresses to complete blindness. The qualifier 'pigmentosa' reflects the fact that clumps of pigment may be visible by an ophthalmoscope in advanced stages of degeneration.

Although Usher syndrome has been classified clinically in several ways, the prevailing approach is to classify it into three clinical sub-types called Usher I, II and III in order of decreasing severity of deafness. Usher I and II are the more common forms; the fraction of people with Usher III is significant only in a few specific areas, such as Finland and Birmingham. As described below, these clinical subtypes may be further subdivided by the particular gene mutated; people with Usher I and II may have any one of six and three genes mutated, respectively, whereas only one gene has been associated with Usher III. The function of these genes is still poorly understood. The hearing impairment associated with Usher syndrome is better understood: damaged hair cells in the cochlea of the inner ear inhibit electrical impulses from reaching the brain.

Usher syndrome, also known as Hallgren syndrome, Usher-Hallgren syndrome, retinitis pigmentosa-dysacusis syndrome, or dystrophia retinae dysacusis syndrome, is an extremely rare genetic disorder caused by a mutation in any one of at least 11 genes resulting in a combination of hearing loss and visual impairment. It is a leading cause of deafblindness and is at present incurable.

Usher syndrome is classed into three subtypes according to onset and severity of symptoms. All three subtypes are caused by mutations in genes involved in the function of the inner ear and retina. These mutations are inherited in an autosomal recessive pattern.

Professor Hiroaki Ota, a Japanese psychiatrist working in France, is credited as the first person to diagnose the condition in 1986. However, later work by Youcef Mahmoudia, physician with the hospital Hôtel-Dieu de Paris, indicates that Paris syndrome is "a manifestation of psychopathology related to the voyage, rather than a syndrome of the traveller." He theorized that the excitement resulting from visiting Paris causes the heart to accelerate, causing giddiness and shortness of breath, which results in hallucinations in the manner similar to the Stendhal syndrome described by Italian psychiatrist Graziella Magherini in her book "La sindrome di Stendhal".

Craniodiaphyseal dysplasia (also known as CDD or lionitis) is an extremely rare autosomal recessive bone disorder that causes calcium to build up in the skull, disfiguring the facial features and reducing life expectancy.

These calcium deposits decrease the size of cranial foramina, and can also decrease the hole in the cervical spinal canal. In the few cases recorded, most of the sufferers died in childhood.

The underlying genetics are uncertain.

A genetic predisposition is a genetic characteristic which influences the possible phenotypic development of an individual organism within a species or population under the influence of environmental conditions. In medicine, genetic susceptibility to a disease refers to a genetic predisposition to a health problem, which may eventually be triggered by particular environmental or lifestyle factors, such as tobacco smoking or diet. Genetic testing is able to identify individuals who are genetically predisposed to certain diseases.

Chronic radiation syndrome is a constellation of health effects that occur after months or years of chronic exposure to high amounts of ionizing radiation. Chronic radiation syndrome develops with a speed and severity proportional to the radiation dose received, i.e., it is a deterministic effect of radiation exposure, unlike radiation-induced cancer. It is distinct from acute radiation syndrome in that it occurs at dose rates low enough to permit natural repair mechanisms to compete with the radiation damage during the exposure period. Dose rates high enough to cause the acute form (> ~0.1 Gy/h) are fatal long before onset of the chronic form. The lower threshold for chronic radiation syndrome is between 0.7 and 1.5 Gy, at dose rates above 0.1 Gy/yr. This condition is primarily known from the Kyshtym disaster, where 66 cases were diagnosed, and has received little mention in Western literature. A future ICRP publication, currently in draft, may recognize the condition but with higher thresholds.

In 2013, Alexander V. Akleyev described the chronology of the clinical course or CRS while presenting at ConRad in Munich, Germany. In his presentation, he defined the latent period as being 1-5 years, and the formation coinciding with the period of maximum radiation dose. The recovery period was described as being 3-12 months after exposure ceased. He concluded that "CRS represents a systemic response of the body as a whole to the chronic total body exposure in man." In 2014, Akleyev's book "Comprehensive analysis of chronic radiation syndrome, covering epidemiology, pathogenesis, pathoanatomy, diagnosis and treatment" was published by Springer.

Stendhal syndrome, Stendhal's syndrome, hyperkulturemia, or Florence syndrome is a psychosomatic disorder that causes rapid heartbeat, dizziness, fainting, confusion and even hallucinations when an individual is exposed to an experience of great personal significance, particularly viewing art. It is not listed as a recognised condition in the "Diagnostic and Statistical Manual of Mental Disorders".

Among the medical signs are dacryocystitis, seizures, intellectual disability, and paralysis, each of which is a complication resulting from the diminutive foramina. A common sign reported as a result of the disease has been a difference of the size of the eyes.

CDD is a rare condition, with only 1.7 cases per 100,000.

A child affected with childhood disintegrative disorder shows normal development and he/she acquires "normal development of age-appropriate verbal and nonverbal communication, social relationships, motor, play and self-care skills" comparable to other children of the same age. However, between the ages of 2 and 10, skills acquired are lost almost completely in at least two of the following six functional areas:

- Expressive language skills (being able to produce speech and communicate a message)

- Receptive language skills (comprehension of language - listening and understanding what is communicated)

- Social skills and self care skills

- Control over bowel and bladder

- Play skills

- Motor skills

Lack of normal function or impairment also occurs in at least two of the following three areas:

- Social interaction

- Communication

- Repetitive behavior and interest patterns

In her book, "Thinking in Pictures", Temple Grandin argues that compared to "Kanner's classic autism" and to Asperger syndrome, CDD is characterized with more severe sensory processing disorder but less severe cognitive problems. She also argues that compared to most autistic people, persons with CDD have more severe speech pathology and they usually do not respond well to stimulants.

The childhood disintegrative disorder (CDD), also known as Heller's syndrome and disintegrative psychosis, is a rare condition characterized by late onset of developmental delays—or stunning reversals—in language, social function, and motor skills. Researchers have not been successful in finding a cause for the disorder. CDD has some similarity to autism, and is sometimes considered a low-functioning form of it. In May 2013, the term CDD, along with other types of autism, was fused into a single diagnostic term called "autism spectrum disorder" under the new DSM-5 manual. Therefore, CDD is now also called "regressive autism", being that this term can now refer to any type of autism spectrum disorder that involves regression, including CDD.

CDD was originally described by Austrian educator Theodor Heller (1869–1938) in 1908, 35 years before Leo Kanner and Hans Asperger described autism. Heller had previously used the name "dementia infantilis" for the syndrome.

An apparent period of fairly normal development is often noted before a regression in skills or a series of regressions in skills. The age at which this regression can occur varies, but typically after 3 years of normal development. The regression can be so dramatic that the child may be aware of it, and may in its beginning even ask, vocally, what is happening to them. Some children describe or appear to be reacting to hallucinations, but the most obvious symptom is that skills apparently attained are lost.

Many children are already somewhat delayed when the disorder becomes apparent, but these delays are not always obvious in young children. This has been described by many writers as a devastating condition, affecting both the family and the individual's future. As is the case with all pervasive developmental disorder categories, there is considerable controversy about the right treatment for CDD.

A brainstem stroke syndrome is a condition involving a stroke of the brainstem. Because of their location, they often involve impairment both of the cranial nuclei and of the long tracts.

A person may have vertigo, dizziness and severe imbalance without the hallmark of most strokes – weakness on one side of the body. The symptoms of vertigo, dizziness or imbalance usually occur together; dizziness alone is not a sign of stroke. Brainstem stroke can also cause diplopia, slurred speech and decreased level of consciousness. A more serious outcome is locked-in syndrome.

Visual release hallucinations, also known as Charles Bonnet syndrome (CBS), is the experience of complex visual hallucinations in a person with partial or severe blindness. First described by Charles Bonnet in 1760, it was first introduced into English-speaking psychiatry in 1982.

Factitious disorder imposed on self, also known as Munchausen syndrome, is a factitious disorder wherein those affected feign disease, illness, or psychological trauma to draw attention, sympathy, or reassurance to themselves. Munchausen syndrome fits within the subclass of factitious disorder with predominantly physical signs and symptoms, but patients also have a history of recurrent hospitalization, travelling, and dramatic, extremely improbable tales of their past experiences. The condition derives its name from Baron Munchausen.

Factitious disorder imposed on self is related to factitious disorder imposed on another, which refers to the abuse of another person, typically a child, in order to seek attention or sympathy for the abuser. This drive to create symptoms for the victim can result in unnecessary and costly diagnostic or corrective procedures.

In factitious disorder imposed on self, the affected person exaggerates or creates symptoms of illnesses in themselves to gain examination, treatment, attention, sympathy, and/or comfort from medical personnel. In some extreme cases, people suffering from Munchausen syndrome are highly knowledgeable about the practice of medicine and are able to produce symptoms that result in lengthy and costly medical analysis, prolonged hospital stays, and unnecessary operations. The role of "patient" is a familiar and comforting one, and it fills a psychological need in people with this syndrome. This disorder is distinct from hypochondriasis and other somatoform disorders in that those with the latter do not intentionally produce their somatic symptoms. Munchausen syndrome is distinct from other psychiatric disorders such as malingering in that Munchausen does not fabricate symptoms for material gain such as financial compensation, absence from work, or access to drugs.

Risk factors for developing factitious disorder include childhood traumas, growing up with parents/caretakers who were emotionally unavailable due to illness or emotional problems, a serious illness as a child, failed aspirations to work in the medical field, personality disorders, and low self-esteem. Factitious disorder is more common in men and is seen in young or middle-aged adults. Those with a history of working in healthcare are also at greater risk of developing it.

Arrhythmogenic Munchausen syndrome describes individuals who simulate or stimulate cardiac arrhythmias to gain medical attention.

A similar behavior called factitious disorder imposed on another has been documented in the parent or guardian of a child. The adult ensures that his or her child will experience some medical affliction, therefore compelling the child to suffer through treatments and spend a significant portion of their youth in hospitals. Furthermore, a disease may actually be initiated in the child by the parent or guardian. This condition is considered distinct from Munchausen syndrome. There is growing consensus in the pediatric community that this disorder should be renamed "medical abuse" to highlight the harm caused by the deception and to make it less likely that a perpetrator can use a psychiatric defense when harm is done.

Gay bowel syndrome was a medical term first used by Henry L Kazal and colleagues in 1976 to describe the various sexually transmitted perianal and rectal diseases and sexual traumas seen in Kazal's proctology practice, which had many gay patients.

CBS predominantly affects people with visual impairments due to old age, diabetes or other damage to the eyes or optic pathways. In particular, central vision loss due to a condition such as macular degeneration combined with peripheral vision loss from glaucoma may predispose to CBS, although most people with such deficits do not develop the syndrome.

The syndrome can also develop after bilateral optic nerve damage due to methyl alcohol poisoning.

The 1951 Pont-Saint-Esprit mass poisoning, also known as Le Pain Maudit, occurred on 15 August 1951, in the small town of Pont-Saint-Esprit in southern France. More than 250 people were involved, including 50 persons interned in asylums and resulted in 7 deaths. A foodborne illness was suspected, and among these it was originally believed to be a case of "cursed bread" ("pain maudit").

Most academic sources accept ergot poisoning as the cause of the epidemic, while a few theorize other causes such as poisoning by mercury, mycotoxins, or nitrogen trichloride.

Blain was an animal disease of unknown etiology that was well known in the eighteenth- and nineteenth centuries. It is unclear whether it is still extant, or what modern disease it corresponds to.

According to Ephraim Chambers' eighteenth-century "Cyclopaedia, or an Universal Dictionary of Arts and Sciences", blain was "a " (in the archaic eighteenth-century sense of the word, meaning "disease") occurring in animals, consisting in a "Bladder growing on the Root of the Tongue against the Wind-Pipe", which "at length swelling, stops the Wind". It was thought to occur "by great chafing, and heating of the Stomach".

Blain is also mentioned in "Cattle: Their Breeds, Management, and Diseases", published in 1836, where it is also identified as "gloss-anthrax". W. C. Spooner's 1888 book "The History, Structure, Economy and Diseases of the Sheep" also identifies blain as being the same as gloss-anthrax.

Modern scholarship suggests that "gloss-anthrax" was not the same disease as modern-day anthrax, but instead could have been foot-and-mouth disease, or a viral infection with a secondary "Fusobacterium necrophorum" infection. It has also been suggested that it may have been due to a variant strain of true anthrax that is no longer in existence. Other sources also report epizootics known as "blain" or "black-blain" in the 13th and 14th centuries, but it is not clear if the disease involved was the same as "gloss-anthrax".

Senile osteoporosis, formerly known as osteoporosis type II, has been recently recognized as a geriatric syndrome with a particular pathophysiology.

It has been pointed out that senile osteoporosis is the product of a skeleton in an advanced stage of life and also due to a deficiency caused by calcium, but physicians are also coming to the conclusion that multiple mechanisms in the development stages of the disease interact together and the product is an osteoporotic bone, regardless of age.

Pneumonoultramicroscopicsilicovolcanoconiosis () is a word invented by the president of the National Puzzlers' League as a synonym for the disease known as silicosis. It is the longest word in the English language published in a dictionary, the "Oxford English Dictionary", which defines it as "an artificial long word said to mean a lung disease caused by inhaling very fine ash and sand dust."

Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis.

Victor Khrisanfovich Kandinsky () (1849, Byankino, Siberia - 1889) was a Russian physician, and was 2nd cousin to famed artist Wassily Kandinsky. He was born in Siberia into a large family of extremely wealthy businessmen.

In 1877 as a military physician in the Balkans during the Russo-Turkish War, he began experiencing mood swings and hallucinations. Kandinsky performed self-diagnosis, and he referred to his mental condition as "Primäre Verrücktheit" (primary paranoid psychosis) which has been anachronistically translated into modern terms as a "schizophrenic-like state". In 1885 Kandinsky published a book written in German on "pseudohallucinations" in which he describes and details hallucinations largely based on his personal experiences. In September 1889, feeling that his psychotic symptoms were returning, he took his own life by taking an overdose of morphine. He died as a patient in the institution he had formerly run as the medical superintendent, the St. Nicholas Asylum in St. Petersburg.

In a monograph published posthumously in 1890, Kandinsky described a condition which involved being alienated from one's personal mental processes, combined with delusions of being physically and mentally influenced by external forces. The syndrome he described is now known as Kandinsky-Clérambault syndrome, named along with French psychiatrist Gaëtan Gatian de Clérambault. The syndrome also known as "syndrome of psychic automatism".

Koro is a culture-specific syndrome delusional disorder in which an individual has an overpowering belief that one's genitalia are retracting and will disappear, despite the lack of any true longstanding changes to the genitals. Koro is also known as shrinking penis, and it is listed in the "Diagnostic and Statistical Manual of Mental Disorders". The syndrome occurs worldwide, and mass hysteria of genital-shrinkage anxiety has a history in Africa, Asia, and Europe. In the United States and Europe, the syndrome is commonly known as genital retraction syndrome. The condition can be diagnosed through psychological assessment along with physical examination to rule out genuine disorders of the genitalia that could be causing true retraction.