It is a genetic developmental disorder with clinical diversity characterized by hypoparathyroidism, sensorineural deafness and renal disease. Patients usually present with hypocalcaemia, tetany, or afebrile convulsions at any age. Hearing loss is usually bilateral and may range from mild to profound impairment. Renal disease includes nephrotic syndrome, cystic kidney, renal dysplasia, hypoplasia or aplasia, pelvicalyceal deformity, vesicoureteral reflux, chronic kidney disease, hematuria, proteinuria and renal scarring.

The main symptoms are given by its name: dry, scaly skin (ichthyosis), absence of hair (atrichia) and excessive sensitivity to light (photophobia). Additional features include short stature, mental retardation, seizures and a tendency for respiratory infections.

It involves numerous anomalies including:

- Post-axial polydactyly

- Congenital heart defects (most commonly an atrial septal defect producing a common atrium, occurring in 60% of affected individuals)

- Teeth present at birth (natal teeth)

- Fingernail dysplasia

- Short-limbed dwarfism, mesomelic pattern

- Short ribs

- Cleft palate

- Malformation of the wrist bones (fusion of the hamate and capitate bones).

Barakat syndrome, is a rare disease characterized by hypoparathyroidism, sensorineural deafness and renal disease, and hence also known as HDR syndrome. It was first described by Amin J. Barakat et al. in 1977.

IFAP syndrome is an extremely rare genetic syndrome. It is also known as Ichthyosis follicularis, alopecia, and photophobia syndrome or simply ichthyosis follicularis. It is extremely rare: there were only 10 known cases (all male) in 1998.

Melkersson–Rosenthal syndrome (also termed "Miescher-Melkersson-Rosenthal syndrome"), is a rare neurological disorder characterized by recurring facial paralysis, swelling of the face and lips (usually the upper lip - cheilitis granulomatosis) and the development of folds and furrows in the tongue (fissured tongue). Onset is in childhood or early adolescence. After recurrent attacks (ranging from days to years in between), swelling may persist and increase, eventually becoming permanent. The lip may become hard, cracked, and fissured with a reddish-brown discoloration. The cause of Melkersson–Rosenthal syndrome is unknown, but there may be a genetic predisposition. It has been noted to be especially prevalent among certain ethnic groups in Bolivia. It can be symptomatic of Crohn's disease or sarcoidosis. Approximately 400 cases have been reported worldwide.

The appearance of people with the disorder is caused by a loss of bone in the mandible which the body replaces with excessive amounts of fibrous tissue. In most cases, the condition fades as the child grows, but in a few even rarer cases the condition continues to deform the affected person's face. Cherubism also causes premature loss of the primary teeth and uneruption of the permanent teeth.

The condition Cherubism is a rare autosomal dominant disease of the maxilla and mandible. Approximately 200 cases have been reported by medical journals with the majority being males. Cherubism is usually first diagnosed around age 7 and continues through puberty and may or may not continue to advance with age. The degrees of Cherubism vary from mild to severe. Osteoclastic and osteoblastic remodeling contributes to the change of normal bone to fibrous tissue and cyst formation. As noted by the name, the patient's face becomes enlarged and disproportionate due to the fibrous tissue and atypical bone formation. The sponge-like bone formations lead to early tooth loss and permanent tooth eruption problems. The condition also affects the orbital area, creating an upturned eye appearance. The cause of cherubism is believed to be traced to a genetic defect resulting from a mutation of the SH3BP2 gene from chromosome 4p16.3. While the condition is rare and painless, the afflicted suffer the emotional trauma of disfigurement. The effects of Cherubism may also interfere with normal jaw motion and speech. Currently, removal of the tissue and bone by surgery is the only treatment available. This condition is also one of the few that unexpectedly stops and regresses. Normal bone remodeling activity may resume after puberty.

Cherubism is displayed with genetic conformation and when excessive osteoclasts are found in the affected areas of the mandible and maxilla. Large cysts will be present with excessive fibrous areas inside the bone. The fibers and cysts will be found among the trabecula of the Coronoid process, the ramus of mandible, the body of mandible and the maxilla regions. The maxilla will be affected up to and including the orbits and sometimes inside the lower orbits. The maxilla and zygomatic bones are depressed and eyes appear to gaze upward. The maxilla has been found to be more severely affected in most cases than the mandible bone. Some patients found with lower inner orbital growths and cysts may lose vision.

Zeichi-Ceide syndrome is a rare disease discovered in 2007. It is named after its discoverer, R.M. Zeichi-Ceide, who observed three siblings born of consanguineous parents with distinctive characteristics, including facial anomalies, large feet, mental deficiency, and occipital atretic cephalocele. The investigators suspected the symptoms were caused by autosomal recessive inheritance.

As a rare disease, Zeichi-Ceide syndrome is registered in the Online Mendelian Inheritance in Man and the U.S. National Institutes of Health's Genetic and Rare Diseases databases.

Males

In males the symptoms of Danon Disease are more severe. Features of Danon Disease in males are:

- An early age of onset of muscle weakness and heart disease (onset in childhood or adolescence)

- Some learning problems or intellectual disability can be present

- Muscle weakness can be severe and can affect endurance and the ability to walk

- Heart disease (cardiomyopathy) can be severe and can lead to a need for medications. It usually progress to heart failure, commonly complicated by atrial fibrillation and embolic strokes with severe neurological disability, leading to death unless heart transplant is performed.

- Cardiac conduction abnormalities can occur. Wolff-Parkinson-White syndrome is a common conduction pattern in Danon disease.

- Symptoms are usually gradually progressive

- Some individuals may have visual disturbances, and/or retinal pigment abnormalities

- Danon Disease is rare and unfamiliar to most physicians. It can be mistaken for other forms of heart disease and/or muscular dystrophies, including Pompe disease.

Females

In females the symptoms of Danon Disease are less severe. Common symptoms of Danon Disease in females are:

- A later age of onset of symptoms. Many females will not have obvious symptoms until late adolescence or even adulthood.

- Learning problems and intellectual disability are usually ABSENT

- Muscle weakness is often absent or subtle. Some females will tire easily with exercise

- Cardiomyopathy) is often absent in childhood. Some women will develop this in adulthood. Cardiomyopathy can be associated with atrial fibrillation and embolic strokes.

- Cardiac conduction abnormalities can occur. Wolff-Parkinson-White syndrome is a common conduction pattern in Danon disease.

- Symptoms in females progress more slowly than in males.

- Some females may have visual disturbances, and/or retinal pigment abnormalities

- Danon Disease is rare and unfamiliar to most physicians. The milder and more subtle symptoms in females can make it more difficult to diagnose females with Danon Disease

A genetic disorder is a genetic problem caused by one or more abnormalities in the genome, especially a condition that is present from birth (congenital). Most genetic disorders are quite rare and affect one person in every several thousands or millions.

Genetic disorders may be hereditary, passed down from the parents' genes. In other genetic disorders, defects may be caused by new mutations or changes to the DNA. In such cases, the defect will only be passed down if it occurs in the germ line. The same disease, such as some forms of cancer, may be caused by an inherited genetic condition in some people, by new mutations in other people, and mainly by environmental causes in other people. Whether, when and to what extent a person with the genetic defect or abnormality will actually suffer from the disease is almost always affected by the environmental factors and events in the person's development.

Some types of recessive gene disorders confer an advantage in certain environments when only one copy of the gene is present.

Retinal lesions, called astrocytic hamartomas (or "phakomas"), which appear as a greyish or yellowish-white lesion in the back of the globe on the ophthalmic examination. Astrocytic hamartomas can calcify, and they are in the differential diagnosis of a calcified globe mass on a CT scan.

Nonretinal lesions associated with TSC include:

- Coloboma

- Angiofibromas of the eyelids

- Papilledema (related to hydrocephalus)

Due to the wide range of genetic disorders that are presently known, diagnosis of a genetic disorder is widely varied and dependent of the disorder. Most genetic disorders are diagnosed at birth or during early childhood, however some, such as Huntington's disease, can escape detection until the patient is well into adulthood.

The basic aspects of a genetic disorder rests on the inheritance of genetic material. With an in depth family history, it is possible to anticipate possible disorders in children which direct medical professionals to specific tests depending on the disorder and allow parents the chance to prepare for potential lifestyle changes, anticipate the possibility of stillbirth, or contemplate termination. Prenatal diagnosis can detect the presence of characteristic abnormalities in fetal development through ultrasound, or detect the presence of characteristic substances via invasive procedures which involve inserting probes or needles into the uterus such as in amniocentesis.

Zamzam–Sheriff–Phillips syndrome is a rare autosomal recessive congenital disorder. It is characterized by aniridia, ectopia lentis, abnormal upper incisors and intellectual disability. Not a lot of research has been undertaken of this particular disease so thus far there is no known gene that affects this condition. However it has been hypothesised that the symptoms described are found at a particular gene, though intellectual disability is believed to be due to a different genetic cause.

Consanguinuity (intermarrying among relatives such as cousins), often associated with autosomal recessive inheritance, has been attributed to the inheritance of this disease.

Ichthyosis is a family of rare genetic skin disorders characterized by dry, thickened, scaly skin.

There are more than 20 types of ichthyosis which range in severity of symptoms, outward appearance, underlying genetic cause, and mode of inheritance (e.g., whether the abnormal gene inherited is dominant, recessive, autosomal, or X-linked). Ichthyosis comes from the , since dry, scaly skin is the defining feature of all forms of ichthyosis.

The severity of symptoms can vary enormously, from the mildest, most common, type such as ichthyosis vulgaris which may be mistaken for normal dry skin up to life-threatening conditions such as harlequin type ichthyosis. Ichthyosis vulgaris accounts for more than 95% of cases.

Conradi–Hünermann syndrome is a form of chondrodysplasia punctata, a group of rare genetic disorders of skeletal development involving abnormal accumulations of calcium salts within the growing ends of long bones. Conradi–Hünermann syndrome is commonly associated with mild to moderate growth deficiency, disproportionate shortening of long bones, particularly those of the upper arms and the thigh bones, short stature, and/or curvature of the spine. In rare cases, intellectual disability may also be present. While evidence suggests that Conradi–Hünermann syndrome predominantly occurs in females and is usually inherited as an X-linked dominant trait, rare cases in which males were affected have also been reported.

The genetics of Conradi–Hünermann syndrome has perplexed medical geneticists, pediatricians and dermatologists for some time, but a number of perplexing features of the genetics of the syndrome have now been resolved, including the fact that the disease is caused by mutations in a gene, and these mutations are simple substitutions, deletions or insertions and are therefore not "unstable". Scientists are still trying to understand exactly where the mutation occurs so that they can correct it.

Diagnosis is mainly based on clinical features. However, biopsy has been useful in diagnosis as well as in differentiating between the different types of the disease.

Conradi–Hünermann syndrome (also known as "Conradi–Hünermann–Happle syndrome", "Happle syndrome," and "X-linked dominant chondrodysplasia punctata") is a type of chondrodysplasia punctata. It is associated with the gene EBP (gene) and affects between one in 100,000 and one in 200,000 babies.

Some form of dermatological sign is present in 96% of individuals with TSC. Most cause no problems, but are helpful in diagnosis. Some cases may cause disfigurement, necessitating treatment. The most common skin abnormalities include:

- Facial angiofibromas ("adenoma sebaceum"): A rash of reddish spots or bumps, which appears on the nose and cheeks in a butterfly distribution, they consist of blood vessels and fibrous tissue. This potentially socially embarrassing rash starts to appear during childhood and can be removed using dermabrasion or laser treatment.

- Periungual fibromas: Also known as Koenen's tumors, these are small fleshy tumors that grow around and under the toenails or fingernails and may need to be surgically removed if they enlarge or cause bleeding. These are very rare in childhood, but common by middle age. They are generally more common on toes than on fingers, develop at 15–29 years, and are more common in women than in men. They can be induced by nail-bed trauma.

- Hypomelanic macules ("ash leaf spots"): White or lighter patches of skin, these may appear anywhere on the body and are caused by a lack of melanin. They are usually the only visible sign of TSC at birth. In fair-skinned individuals, a Wood's lamp (ultraviolet light) may be required to see them.

- Forehead plaques: Raised, discolored areas on the forehead

- Shagreen patches: Areas of thick leathery skin that are dimpled like an orange peel, and pigmented, they are usually found on the lower back or nape of the neck, or scattered across the trunk or thighs. The frequency of these lesions rises with age.

- Other skin features are not unique to individuals with TSC, including molluscum fibrosum or skin tags, which typically occur across the back of the neck and shoulders, "café au lait" spots or flat brown marks, and poliosis, a tuft or patch of white hair on the scalp or eyelids.

The syndrome was first reported in an eight-year-old boy, but very few cases have been reported since then. The syndrome is detected by abnormalities noted at birth involving the head, limbs, heart, ears, and skin. It is characterized by premature closure of the fibrous joints between certain bones of the skull in a process known as craniosynostosis. As documented in the first case, the victim tends to suffer from cyanosis and other respiratory and breathing infections, all before the age of one. Body development subsequently slows down, but some problems can be fixed under proper guidance, such as learning to walk with special crutches by five years of age. Craniofacial problems are present that have no effect on the patient's intelligence and mental growth.

Most problems resulting from the syndrome are physical. It causes acrocephaly, making the head appear pointed, and webbing or syndactyly of certain toes or fingers.

The chemical imbalance is usually diagnosed when dental abnormalities are found. These abnormalities include premature deciduous teeth and abnormal growth of permanent teeth due to displacement by cysts and lesions. The only definite way to correctly diagnose the condition is by sequence analysis of the SH3BP2 gene. The gene has been found to have missense mutation in exon 9. Initial study of the patient is usually conducted using x-ray and CT scans. Neurofibromatosis may resemble Cherubism and may accompany the condition. Genetic testing is the final diagnosis tool.

There are three main disorders caused by Hermansky–Pudlak syndrome, which result in these symptoms:

- Albinism and eye problems: Individuals will have varying amounts of skin pigment (melanin). Because of the albinism there are eye problems such as light sensitivity (photophobia), strabismus (crossed eyes), and nystagmus (involuntary eye movements). Hermansky–Pudlak syndrome also impairs vision.

- Bleeding disorders: Individuals with the syndrome have platelet dysfunction. Since platelets are necessary for blood clotting, individuals will bruise and bleed easily.

- Cellular storage disorders: The syndrome causes a wax-like substance (ceroid) to accumulate in the body tissues and cause damage, especially in the lungs and kidneys.

It is also associated with granulomatous colitis, an inflammation of the colon, and with pulmonary fibrosis, a potentially fatal lung disease.

The three most common symptoms of Opitz G/BBB syndrome (both type I & II) are hypertelorism (exceptionally wide-spaced eyes), laryngo-tracheo-esophalgeal defects (including clefts and holes in the palate, larynx, trachea and esophagus) and hypospadias (urinary openings in males not at the tip of the penis) (Meroni, Opitz G/BBB syndrome, 2012). Abnormalities in the larynx, trachea and esophagus can cause significant difficulty breathing and/or swallowing and can result in reoccurring pneumonia and life-threatening situations. Commonly, there may be a gap between the trachea and esophagus, referred to as a laryngeal cleft; which can allow food or fluid to enter the airway and make breathing and eating a difficult task.

Genital abnormalities like a urinary opening under the penis (hypospadias), undescended testes (cryptorchidism), underdeveloped scrotum and a scrotum divided into two lobes (bifid scrotum) can all be commonplace for males with the disease.

Developmental delays of the brain and nervous system are also common in both types I and II of the disease. 50% of people with Opitz G/BBB Syndrome will experience developmental delay and mild intellectual disability. This can impact motor skills, speech and learning capabilities. Some of these instances are likened to autistic spectrum disorders. Close to half of the people with Opitz G/BBB Syndrome also have a cleft lip (hole in the lip opening) and possibly a cleft palate (hole in the roof of the mouth), as well. Less than half of the people diagnosed have heart defects, imperforate anus (obstructed anal opening), and brain defects. Of all the impairments, female carriers of X-linked Type I Opitz G/BBB Syndrome usually only have ocular hypertelorism.

Familial progressive hyperpigmentation is characterized by patches of hyperpigmentation, present at birth, which increase in size and number with age. This is a genetic disease, however the gene that accounts for this spotty darkening of the skin has yet to be discovered. Although rare, the congenital disease is most prevalent among populations originating from China.

"Maffucci syndrome" is a sporadic disease characterized by the presence of multiple enchondromas associated with multiple simple or cavernous soft tissue hemangiomas. Also lymphangiomas may be apparent.

Patients are normal at birth and the syndrome manifests during childhood and puberty. The enchondromas affect the extremities and their distribution is asymmetrical.

There are many types of ichthyoses and an exact diagnosis may be difficult. Types of ichthyoses are classified by their appearance and their genetic cause. Ichthyosis caused by the same gene can vary considerably in severity and symptoms. Some ichthyoses do not appear to fit exactly into any one type. Different genes can produce ichthyoses with similar symptoms. Of note, X-linked ichthyosis is associated with Kallmann syndrome (close to "KAL1" gene). The most common or well-known types are as follows: