Parry–Romberg syndrome appears to occur randomly and for unknown reasons. Prevalence is higher in females than males, with a ratio of roughly 3:2. The condition is observed on the left side of the face about as often as on the right side.

The fact that some people affected with this disease have circulating antinuclear antibodies in their serum supports the theory that Parry–Romberg syndrome may be an autoimmune disease, specifically a variant of localized scleroderma. Several instances have been reported where more than one member of a family has been affected, prompting speculation of an autosomal dominant inheritance pattern. However, there has also been at least one report of monozygotic twins in which only one of the twins was affected, casting doubt on this theory. Various other theories about the cause and pathogenesis have been suggested, including alterations in the peripheral sympathetic nervous system (perhaps as a result of trauma or infection involving the cervical plexus or the sympathetic trunk), as the literature reported it following sympathectomy, disorders in migration of cranial neural crest cells, or chronic cell-mediated inflammatory process of the blood vessels. It is likely that the disease results from different mechanisms in different people, with all of these factors potentially being involved.

In terms of epidemiology, Jackson–Weiss syndrome is a rare genetic disorder; the overall contribution of FGFR mutation to the condition is not clear.

Estimating the mortality rate based on the available literature is difficult. Several case reports have revealed an association between acquired partial lipodystrophy and other diseases.

Nephropathy, in the form of membranoproliferative glomerulonephritis, occurs in about 20% of patients. Usually, patients do not have clinically evident renal disease or abnormalities in renal function until they have had the disease for 8 or more years. Membranoproliferative glomerulonephritis usually presents with asymptomatic proteinuria or hematuria.

The disease may gradually progress. About 40-50% of patients develop end-stage renal disease over the course of 10 years. This condition is responsible for most recurrent hospital admissions in patients with acquired partial lipodystrophy. Rapid progression of renal disease in a pregnant patient was reported. Recurrent disease in transplanted kidneys is common, although there have been reports of successful transplantations.

Associated autoimmune diseases (e.g., systemic lupus erythematosus, thyroiditis) contribute significantly to increased morbidity in these patients compared with the general population. Although uncommon, insulin resistance increases cardiovascular risk. Susceptibility to bacterial infections probably results from a C3 deficiency (due to complement activation and consumption of C3). Low C3 levels may impair complement-mediated phagocytosis and bacterial killing.

Around 250 cases have been reported since the recognition of this syndrome. It is a rare syndrome with no known prevalence, although it is more common than the generalized form of acquired lipodystrophy (Lawrence syndrome).

- Race: No clear relationship exists between incidence and race in this syndrome; however, most reported patients have been of European descent.

- Age: The median age of onset of lipodystrophy has been reported to be around seven years; however, onset occurring as late as the fourth or fifth decade of life also has been reported. The median age at presentation has been about 25 years, and women have been found to present later than men (age 28 for women, age 18 for men).

- Sex: Analysis of the pooled data revealed female patients were affected about four times more often than males.

The condition develops in the fetus at approximately 4 weeks gestational age, when some form of vascular problem such as blood clotting leads to insufficient blood supply to the face. This can be caused by physical trauma, though there is some evidence of it being hereditary . This restricts the developmental ability of that area of the face. Currently there are no definitive reasons for the development of the condition.

Hemifacial microsomia (HFM) is a congenital disorder that affects the development of the lower half of the face, most commonly the ears, the mouth and the mandible. It usually occurs on one side of the face, but both sides are sometimes affected. If severe, it may result in difficulties in breathing due to obstruction of the trachea—sometimes even requiring a tracheotomy. With an incidence in the range of 1:3500 to 1:4500, it is the second most common birth defect of the face, after cleft lip and cleft palate. HFM shares many similarities with Treacher Collins syndrome.

One dental textbook defines it as: “Dollicofacial, there is excess of lower facial height usually associated with lower occlusal and mandibular plane angles.” This is often associated “with vertical maxillary excess and mandibular hypoplasia.” Luc P. M. Tourne, a Fellow in the Department of TMJ and Craniofacial Pain at the University of Minnesota School of Dentistry, noted: "There is a clinically recognizable facial morphology, the long face syndrome, which has been incompletely described in the literature," However, her study of 31 adults with this syndrome, which included "analysis of esthetics, skeletal morphology, and occlusion" confirmed "this basic dentofacial deformity" has associations " with excessive vertical growth of the maxilla." She reported that closed bite and dental open are two pf the syndrome's variants.

The treatment for young patients troubled by long face syndrome is to halt and control descent of the lower jaw and to prevent the eruption of posterior teeth. In severe cases of deformity, a mixture of orthodontics and orthognathic surgery may be the only effective solution. The long term (more than 6 years) effectiveness of surgical treatments for long face syndrome has been subject to study.

"In the American literature, the terms long-face syndrome and short-face syndrome are often used." To be sure, there are reported "long and the short face anomalies" and open bite cases. However, in the opinion of Hugo Obwegeser, there is no medical justification for naming theme as a "syndrome" the signs and symptoms do not meet the definitional threshold.

There is controversy concerning the use of the descriptor "long-face syndrome." While increased anterior "total and lower face height" in many ages, combined with vertical maxillary excess in adults has been observed, the causes are controversial. Specifically, there is disagreement about possible potential environmental influences on genetic components.

Anecdotally, it was said to be a genetic condition, which could only be corrected with “massive amounts” of debilitating, frequent and long dental and facial reconstructive surgery.

For children, there is a concern that mouth breathing can contribute to the development of long face syndrome. A recent study finds that it is a growing problem which should be treated as "It won't just go away." In addition to mouth breathing, it may be associated with sleep apnea.

Because of Long face syndrome's sometime association with pediatric obstructive sleep apnea (OSA) and allergic reactions, it is essential that treating physicians differentiate the conditions and the treatments; treating one may not cure the other. Multilevel coblation surgery is sometimes used to correct moderate to severe OSA, and Long Face Syndrome can be a rare factor in considering surgery.

Long face syndrome, also referred to as skeletal open bite, is a relatively common condition experienced by orthodontic patients which caused excessive vertical facial development. Its causes may be either genetic or environmental. Long face syndrome is “a common dentofacial abnormality.” Its diagnosis, symptomology and treatments are complex and controversial. Indeed, even its existence as a "syndrome" is disputed.

TCS occurs in about one in 50,000 births in Europe. Worldwide, it is estimated to occur in one in 10,000 to one in 50,000 births.

In 2016, interferon gamma/CXCL10 axis was hypothesized to be a target for treatments that reverse inflammation. Apremilast is undergoing investigation as a potential treatment .

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

The overall prevalence of lichen planus in the general population is about 0.1–4.0%. It generally occurs more commonly in females, in a ratio of 3:2, and most cases are diagnosed between the ages of 30 and 60, but it can occur at any age.

Oral lichen planus is relatively common, It is one of the most common mucosal diseases. The prevalence in the general population is about 1.27–2.0%, and it occurs more commonly in middle aged people. OLP in children is rare. About 50% of females with oral lichen planus were reported to have undiagnosed vulvar lichen planus.

The disorder can be associated with a number of psychological symptoms, anxiety, depression, social phobia, body image disorders, and patients may be subjected to discrimination, bullying and name calling especially when young. A multi-disciplinary team and parental support should include these issues.

Jackson–Weiss syndrome (JWS) is a genetic disorder characterized by foot abnormalities and the premature fusion of certain bones of the skull (craniosynostosis), which prevents further growth of the skull and affects the shape of the head and face. This genetic disorder can also sometimes cause intellectual disability and crossed eyes as well, it was characterized in 1976.

Face distortion derived from the term "distorting the face," refers to the condition of the human face when it comes into contact with an object moving at high enough speed to distort the face. This could result in anything from a concussion, to a broken jaw, to a fractured skull depending on the force of the object while it's moving to when it comes into contact with the face. Most face distortions are shown to be visible only in slow motion, as seen in popular showings of the event.

Sun avoidance, avoidance of tanning booths, and usage of broad spectrum sunscreen that blocks both UVA and UVB.

Identification and avoidance of the offending drug.

For a person to flush is to become markedly red in the face and often other areas of the skin, from various physiological conditions. Flushing is generally distinguished, despite a close physiological relation between them, from blushing, which is milder, generally restricted to the face, cheeks or ears, and generally assumed to reflect emotional stress, such as embarrassment, anger, or romantic stimulation. Flushing is also a cardinal symptom of carcinoid syndrome—the syndrome that results from hormones (often serotonin or histamine) being secreted into systemic circulation.

It has several different types:

- type 1 - Apert syndrome

- type 2 - Crouzon syndrome

- type 3 - Saethre-Chotzen syndrome

- type 5 - Pfeiffer syndrome

A related term, "acrocephalopolysyndactyly" (ACPS), refers to the inclusion of polydactyly to the presentation. It also has multiple types:

- type 1 - Noack syndrome; now classified with Pfeiffer syndrome

- type 2 - Carpenter syndrome

- type 3 - Sakati-Nyhan-Tisdale syndrome

- type 4 - Goodman syndrome; now classified with Carpenter syndrome

- type 5 - Pfeiffer syndrome

It has been suggested that the distinction between "acrocephalosyndactyly" versus "acrocephalopolysyndactyly" should be abandoned.

AGL with autoimmune origin is responsible for about 25% of all AGL reports. Those with autoimmune origin stems from other autoimmune diseases, most commonly with juvenile dermatomyositis and autoimmune hepatitis, but also occurs with rheumatoid arthritis, systemic lupus erythematous, and Sjogren syndrome.

Commonly referred to as the sex flush, vasocongestion (increased blood flow) of the skin can occur during all four phases of the human sexual response cycle. Studies show that the sex flush occurs in approximately 50–75% of females and 25% of males, yet not consistently. The sex flush tends to occur more often under warmer conditions and may not appear at all under lower temperatures.

During the female sex flush, pinkish spots develop under the breasts, then spread to the breasts, torso, face, hands, soles of the feet, and possibly over the entire body. Vasocongestion is also responsible for the darkening of the clitoris and the walls of the vagina during sexual arousal. During the male sex flush, the coloration of the skin develops less consistently than in the female, but typically starts with the epigastrium (upper abdomen), spreads across the chest, then continues to the neck, face, forehead, back, and sometimes, shoulders and forearms.

The sex flush typically disappears soon after reaching orgasm, but in other cases it may take up to two hours or so, and sometimes intense sweating occurs simultaneously.

Although= pseudoporphyria has no predilection toward any one race, it has been shown that fair-skinned children who are highly prone to sunburn are more likely to develop naproxen-induced pseudoporphyria than those children with skin types III or higher. Wallace et al. demonstrated that even in the absence of a history of blistering, children with light skin and blue or green eyes are at an increased risk of developing shallow scars on the face while taking naproxen.

Harlequin syndrome is a condition characterized by asymmetric sweating and flushing on the upper thoracic region of the chest, neck, and face. Harlequin syndrome is considered an injury to the autonomic nervous system (ANS). The ANS controls some of the body's natural processes such as sweating, skin flushing, and pupil response to stimuli. Such individuals with this syndrome have an absence of sweat skin flushing unilaterally; usually on the one side of the face, arms, and chest. It is an autonomic disorder that may occur at any age. Harlequin syndrome affects fewer than 200,000 people in the United States.

Symptoms associated with Harlequin syndrome are more likely to appear when a person has been in the following conditions: exercising, warm environment, and intense emotional situation. Since one side of the body sweats and flushes appropriately to the condition, the other side of the body will have an absence of such symptoms. This syndrome has also been called the "Harlequin sign," and thought to be one of the spectrum of diseases that may cause Harlequin syndrome.

It can also be the outcome of a one sided endoscopic thoracic sympathectomy (ETS) or endoscopic sympathetic blockade (ESB) surgery.

Harlequin syndrome can also be seen as a complication of VA (veno-arterial) extracorporeal membrane oxygenation (ECMO). This involves differential hypoxemia (low oxygen levels in the blood) of the upper body in comparison to the lower body.

The medical aspect of a face distortion is usually the case involving the skull, neck, or brain. whatever treatment for the aftermath of a face distortion depends on the condition of the receiver after the event occurs.

Harlequin syndrome is not debilitating so treatment is not normally necessary. In cases where the individual may feel socially embarrassed, contralateral sympathectomy may be considered, although compensatory flushing and sweating of other parts of the body may occur. In contralateral sympathectomy, the nerve bundles that cause the flushing in the face are interrupted. This procedure causes both sides of the face to no longer flush or sweat. Since symptoms of Harlequin syndrome do not typically impair a person’s daily life, this treatment is only recommended if a person is very uncomfortable with the flushing and sweating associated with the syndrome.