In the absence of congenital heart defects, individuals with situs inversus are phenotypically normal, and can live normal healthy lives, without any complications related to their medical condition. There is a 5–10% prevalence of congenital heart disease in individuals with situs inversus totalis, most commonly transposition of the great vessels. The incidence of congenital heart disease is 95% in situs inversus with levocardia.

Many people with situs inversus totalis are unaware of their unusual anatomy until they seek medical attention for an unrelated condition, such as a rib fracture or a bout of appendicitis. The condition may also be discovered during the administration of certain medicines or during tests such as a Barium meal or enema. The reversal of the organs may then lead to some confusion, as many signs and symptoms will be on the atypical side. For example, if an individual with situs inversus develops appendicitis, they will present to the physician with lower left abdominal pain, since that is where their appendix lies. Thus, in the event of a medical problem, the knowledge that the individual has situs inversus can expedite diagnosis. People with this rare condition should inform their doctors before an examination, so the doctor can redirect their search for heart sounds and other signs. Wearing a medical identification tag can help inform health care providers in the event the person is unable to communicate.

Situs inversus also complicates organ transplantation operations as donor organs will more likely come from situs solitus (normal) donors. As hearts and livers are chiral, geometric problems arise placing an organ into a cavity shaped in the mirror image. For example, a person with situs inversus who requires a heart transplant needs all the vessels to the transplant donor heart reattached to their existing ones. However, the orientation of these vessels in a person with situs inversus is reversed, necessitating steps so that the blood vessels join properly.

Situs inversus (also called situs transversus or oppositus) is a congenital condition in which the major visceral organs are reversed or mirrored from their normal positions. The normal arrangement of internal organs is known as situs solitus while situs inversus is generally the mirror image of situs solitus. Although cardiac problems are more common than in the general population, most people with situs inversus have no medical symptoms or complications resulting from the condition, and until the advent of modern medicine it was usually undiagnosed.

Situs inversus is found in about 0.01% of the population, or about 1 person in 10,000. In the most common situation, situs inversus totalis, it involves complete transposition (right to left reversal) of all of the abdominal organs. The heart is not in its usual position in the left chest, but is on the right, a condition known as dextrocardia (literally, right-hearted). Because the relationship between the organs is not changed, most people with situs inversus have no medical symptoms or complications, although they should wear a medical identification tag to warn emergency medical staff that the patient's internal organs are reversed from normal so they can act accordingly, e.g. by listening for a heartbeat on the right rather than left side of the chest.

In rarer cases such as situs ambiguus or heterotaxy, situs cannot be determined. In these patients, the liver may be midline, the spleen absent or multiple, and the bowel malrotated. Often, structures are duplicated or absent altogether. This is more likely to cause medical problems than situs inversus totalis.

Impossible Syndrome, or Chondrodysplasia situs inversus imperforate anus polydactyly, is a complex combination of human congenital malformations (birth defects).

The malformations include chondrodysplasia (improper growth of bone and cartilage), situs inversus totalis (chest and abdominal organs all a mirror image of normal), cleft larynx and epiglottis, hexadactyly (six digits) on hands and feet, diaphragmatic hernia, pancreatic abnormalities, kidney abnormal on one side and absent on the other side, micropenis and ambiguous genitalia, and imperforate anus.

Only one case of Impossible Syndrome has been reported; the infant was premature and stillborn.

Aglossia (aglossia congenita) is a congenital defect resulting in a partial development or complete absence of a tongue.

Aglossiais commonly associated with craniofacial and limb defects (Adactylia syndrome) and is thought to belong to a family of oromandibular limb hypogenesis syndrome or OLHS. It is believed to be caused by heat-induced vascular disruption near the fourth week of embryonic development.

The first known case was reported in the early 18th century by a member of the prominent De Jussieu family in France and cases to this day remain rare.

There are frequent associated congenital anomalies all related to deviations in the development of anatomical asymmetries in early embryonic stages. These conditions considered together are called "polysplenia syndrome".

Associated conditions include heterotaxy syndrome, intestinal malrotation, situs inversus, biliary atresia, and several cardiac malformations. Associated cardiac conditions include dextrocardia, atrial situs ambiguus, ventricular inversion, and VA concordance with left posterior aorta.

Although present, the multiple small spleens are often ineffective; this is termed functional asplenia.

Hanhart syndrome (also known as Aglossia adactylia; Hypoglossia-hypodactylia syndrome; Peromelia with micrognathia) is a congenital disorder that causes an undeveloped tongue and malformed extremities and fingers.

Polysplenia or Chaudhrey's disease is a congenital disease manifested by multiple small accessory spleens, rather than a single, full-sized, normal spleen. Polysplenia sometimes occurs alone, but it is often accompanied by other developmental abnormalities. Conditions associated with polysplenia include gastrointestinal abnormalities, such as intestinal malrotation or biliary atresia, as well as cardiac abnormalities, such as dextrocardia.

The inheritance of Impossible syndrome is suspected to be autosomal recessive, which means the affected gene is located on an autosome, and two copies of the gene - one from each parent - are required to have an infant with the disorder.

In addition to small palpebral fissures, features include epicanthus inversus (fold curving in the mediolateral direction, inferior to the inner canthus), low nasal bridge, ptosis of the eyelids and telecanthus.

Blepharophimosis syndrome is an autosomal dominant characterized by blepharophimosis (horizontal shortening of the palpebral fissures), ptosis (upper eyelid drooping, usually with the characteristics of congenital ptosis), epicanthus inversus (skin folds by the nasal bridge, more prominent lower than upper lid), and telecanthus (widening of the distance between the medial orbital walls). This syndrome is caused by mutations in the FOXL2 gene, either with premature ovarian failure (BPES type I) or without (BPES type II). It may also be associated with lop ears, ectropion, hypoplasia of superior orbital rims, and hypertelorism.

The most prominent symptoms of BPES are horizontally narrow eyes (blepharophimosis), drooping eyelids (ptosis), and a fold of skin running from the side of the nose to the lower eyelid (epicanthus inversus). Other common symptoms include lack of an eyelid fold, widely spaced eyes (telecanthus), low nose bridge, and ear malformations (including cupping and incomplete development). Rare symptoms include microphthalmos (abnormally small eyes), tear ducts in the wrong location, and high arched palate. Female infertility can occur with type I BPES.

Michels syndrome is a syndrome characterised by intellectual disability, craniosynostosis, blepharophimosis, ptosis, epicanthus inversus, highly arched eyebrows, and hypertelorism. And vary in other symptoms such as asymmetry of the skull, eyelid, and anterior chamber anomalies, cleft lip and palate, umbilical anomalies, and growth and cognitive development.

Twenty to 27% of individuals with a laryngeal cleft also have a tracheoesophageal fistula and approximately 6% of individuals with a fistula also have a cleft. Other congenital anomalies commonly associated with laryngeal cleft are gastro-oesophageal reflux, tracheobronchomalacia, congenital heart defect, dextrocardia and situs inversus. Laryngeal cleft can also be a component of other genetic syndromes, including Pallister-Hall syndrome and G syndrome (Opitz-Friaz syndrome).

Laryngeal cleft is usually diagnosed in an infant after they develop problems with feeding, such as coughing, cyanosis (blue lips) and failing to gain weight over time. Pulmonary infections are also common. The longer the cleft, the more severe are the symptoms. Laryngeal cleft is suspected after a video swallow study (VSS) shows material flowing into the airway rather than the esophagus, and diagnosis is confirmed through endoscopic examination, specifically microlaryngoscopy and bronchoscopy. If a laryngeal cleft is not seen on flexible nasopharyngoscopy, that does not mean that there is not one there. Laryngeal clefts are classified into four types according to Benjamin and Inglis. Type I clefts extend down to the vocal cords; Type II clefts extend below the vocal cords and into the cricoid cartilage; Type III clefts extend into the cervical trachea and Type IV clefts extend into the thoracic trachea. Subclassification of type IV clefts into Type IVA (extension to 5 mm below the innomate artery) and Type IV B (extension greater than 5 mm below the innominate artery) may help with preoperative selection of those who can be repaired via transtracheal approach (Type IV A) versus a cricotracheal separation approach (type IV B).

Blepharophimosis, ptosis, epicanthus inversus syndrome or BPES is a rare disease characterized by the conditions it is named after: blepharophimosis, ptosis, and epicanthus inversus.

Examples of congenital disorders which affect the tongue include:

- Aglossia - complete absence of the tongue at birth

- Ankyloglossia (tongue tie) - where the lingual frenum tethers the tongue to the floor of the mouth. If it interferes with oral hygiene and feeding, frenectomy may be indicated.

- Hypoglossia - congenitally short tongue

- Microglossia

- Macroglossia - an abnormally large tongue, seen in some disorders such as Down syndrome (although macroglossia can be an acquired condition as well).

- Hamartomata - for example Leiomyomatous hamartoma

- Glossoptosis

- Choristomata - For example, osseous choristoma of the tongue, a very rare condition characterized by a nodule on the dorsum of the tongue containing mature lamellar bone without osteoblastic or osteoclastic activity. Cartilagenous (chondroid), and glial choristomas may also very rarely occur on the tongue.

- Lingual thyroid

- Cleft tongue (bifid tongue) - completely cleft tongue is a rare condition caused by a failure of the lateral lingual swellings to merge. More common is an incompletely cleft tongue, appearing as midline fissure. This is normally classed as fissured tongue.

Situs ambiguus or situs ambiguous, also known as heterotaxy or heterotaxia, is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen. Heterotaxy in general refers to any defect of left-right laterality and arrangement of the visceral organs. This does not include the congenital defect situs inversus, which results when arrangement of the organs in the abdomen and chest are mirrored, so the positions are opposite the normal placement. Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs. Patients with situs ambiguous are considered isomeric in that they have organs with two right-sides or two left-sides, most commonly observed in relation to the atria of the heart.

Individuals with situs inversus or situs solitus do not experience fatal dysfunction of their organ systems, as general anatomy and morphology of the abdominothoracic organ-vessel systems are conserved. Due to abnormal arrangement of organs in situs ambiguous, orientation across the left-right axis of the body is disrupted early in fetal development, resulting in severely flawed cardiac development and function in 50–80% of cases. They also experience complications with systemic and pulmonary blood vessels, significant morbidity, and sometimes death. All patients with situs ambiguus lack lateralization and symmetry of organs in the abdominal and thoracic cavities and are clinically considered to have a form of heterotaxy syndrome.

Heterotaxy syndrome with atrial isomerism occurs in 1 out of every 10,000 live births and is associated with approximately 3% of congenital heart disease cases. Additional estimation of incidence and prevalence of isomerism proves difficult due to failure to diagnose and underestimation of the disease by clinicians. Furthermore, right isomerism is much more easily recognized than left isomerism, contributing to the failure to diagnose.

Situs ambiguous is a growing field of research with findings dating back to 1973.

There are a variety of clinical manifestations of situs ambiguous. Acute symptoms can be due to both cardiac and non-cardiac defects. Cyanosis or blue skin coloration, primarily affecting the lips and fingernails, can indicate a systemic or circulatory issue. Poor feeding, failure to thrive, and rapid shallow breathing may also be observed due to poor circulation. Upon examination, arrhythmia and heart murmur may raise further suspicion of a cardiac abnormality. Non-cardiac symptoms include impairments of the liver and gastrointestinal tract. Biliary atresia, or inflammation and destruction of the bile ducts, may lead to jaundice. Vomiting and swelling of the abdominal region are features that suggest improper positioning of the intestines. Poor positioning of the intestine also makes it more prone to blockage, which can result in numerous chronic health issues. Asplenia and polysplenia are also possible features of heterotaxy syndrome.

Due to abnormal cardiac development, patients with situs ambiguous usually develop right atrial isomerism consisting of 2 bilaterally paired right atria, or left atrial isomerism consisting of 2 bilaterally paired left atria. Clinical features and symptoms can vary dependent upon assignment of left versus right atrial isomerism. In either instance, the apex of the heart will be poorly positioned, which should alert a clinician of the likelihood of atrial isomerism. It is estimated that 5-10% of isomeric patients have mesocardia, in which the heart is positioned at the center of the thorax, 25-50% have dextrocardia, in which the apex of the heart is pointed toward the right side of the thorax, and 50 - 70% have levocardia, in which the apex of the heart is pointed toward the left side of the thorax.

These are pleomorphic and include

- dolichocephaly (with or without sagittal suture synostosis)

- microcephaly

- pre- and postnatal growth retardation

- brachydactyly

- narrow thorax

- rhizomelic dwarfism

- epicanthal folds

- hypodontia and/or microdontia

- sparse, slow-growing, hyperpigmented, fine hair

- nail dysplasia

- hypohydrosis

- chronic renal failure

- heart defects

- liver fibrosis

- visual deficits

- photophobia

- hypoplasia of the posterior corpus callosum

- aberrant calcium homeostasis

Electroretinography shows gross abnormalities.

Two fetuses of 19 and 23 weeks gestation have also been reported. They showed acromesomelic shortening, craniofacial characteristics with absence of craniosynostosis, small kidneys with tubular and glomerular microscopic cysts, persistent ductal plate with portal fibrosis in the liver, small adrenals, an enlarged cisterna magna and a posterior fossa cyst.

Dextrocardia with situs inversus refers to the heart being a mirror image situated on the right side. For all visceral organs to be mirrored, the correct term is dextrocardia situs inversus totalis.

Although statistically people with dextrocardia do not have any medical problems from the disorder, they may be prone to a number of bowel, esophageal, bronchial and cardiovascular disorders (such as double outlet right ventricle, endocardial cushion defect and pulmonary stenosis). Certain cardiovascular and pulmonary disorders related to dextrocardia can be life-threatening if left unchecked (see reference).

Kartagener syndrome may also be present in patients with dextrocardia but this must be in the setting of situs inversus and may include male infertility.

In this form of dextrocardia, the heart is simply placed further right in the thorax than is normal. It is commonly associated with severe defects of the heart and related abnormalities including pulmonary hypoplasia.

Levocardia is a medical condition where the heart is on the normal side of the body (the left), as opposed to dextrocardia, in which the heart is in the right side of the thoracic cavity. This can be associated with "situs solitus", where the remainder of the organs are on normal side as well; or "situs inversus", in which the viscera (stomach, liver, intestines, lungs, etc.) on the opposite side as normal. The latter condition may or may not be associated with clinically relevant abnormalities.

Pterygium inversum unguis (also known as "Pterygium inversus unguis," and "Ventral pterygium") is characterized by the adherence of the distal portion of the nailbed to the ventral surface of the nail plate. The condition may be present at birth or acquired, and may cause pain with manipulation of small objects, typing, and close manicuring of the nail.

Sensenbrenner syndrome (OMIM #218330) is a rare (less than 20 cases reported by 2010) multisystem disease first described in 1975. It is inherited in an autosomal recessive fashion, and a number of genes appear to be responsible. Three genes responsible have been identified: intraflagellar transport (IFT)122 (WDR10), IFT43 — a subunit of the IFT complex A machinery of primary cilia, and WDR35 (IFT121: TULP4)

It is also known as Sensenbrenner–Dorst–Owens syndrome, Levin Syndrome I and cranioectodermal dysplasia (CED)

Tongue diseases can be congenital or acquired, and are multiple in number. Considered according to a surgical sieve, some example conditions which can involve the tongue are discussed below. Glossitis is a general term for tongue inflammation, which can have various etiologies, e.g. infection.