Epidermolysis bullosa simplex (EBS),is a disorder resulting from mutations in the genes encoding keratin 5 or keratin 14.

Blister formation of EBS occurs at the dermoepidermal junction. Sometimes EBS is called "epidermolytic".

Epidermolysis bullosa simplex may be divided into multiple types:

Epidermolysis bullosa (EB) is a group of mainly inherited connective tissue diseases that cause blisters in the skin and mucosal membranes, with an incidence of 20 per million newborns in the United States. It is a result of a defect in anchoring between the epidermis and dermis, resulting in friction and skin fragility. Its severity ranges from mild to lethal.

The condition was brought to public attention in 2004 in the UK through the Channel 4 documentary "The Boy Whose Skin Fell Off", chronicling the life and death of Jonny Kennedy, an Englishman with EB. In the United States, the same could be said of the HBO documentary "My Flesh and Blood" from 2003.

"Butterfly Children" is a term often used to describe younger patients (because the skin is said to be as fragile as a butterfly’s wings), "Cotton Wool Babies", or (in South America) as "Crystal Skin Children".

Epidermolysis bullosa refers to a group of disorders that involve the formation of blisters following trivial trauma. Over 300 mutations have been identified in this condition. They have been classified into the following types:

Phakomatoses are inconsistently defined, and there is a lack of consensus about what conditions are included in this category.

Conditions included are:

- Ataxia telangiectasia

- Incontinentia pigmenti

- Neurofibromatosis

- Nevoid basal cell carcinoma syndrome

- Sturge-Weber syndrome

- Tuberous sclerosis

- Wyburn-Mason syndrome (Bonnet–Dechaume–Blanc syndrome)

- von Hippel-Lindau disease

The first signs of erythema nodosum are often flu-like symptoms such as a fever, cough, malaise, and aching joints. Some people also experience stiffness or swelling in the joints and weight loss.

Erythema nodosum is characterised by nodules (rounded lumps) below the skin surface, usually on the shins. These subcutaneous nodules can appear anywhere on the body, but the most common sites are the shins, arms, thighs, and torso. Each nodule typically disappears after around two weeks, though new one may continue to form for up to six or eight weeks. A new nodule usually appears red and is hot and firm to touch. The redness starts to fade and it gradually becomes softer and smaller until it disappears. Each nodule usually heals completely without scarring over the course of about two weeks. Joint pain and inflammation sometimes continues for several weeks or months after the nodules appear.

Less common variants of erythema nodosum include:

- Ulcerating forms, seen in Crohn's disease

- Erythema contusiforme, when a subcutaneous hemorrhage (bleeding under the skin) occurs with a erythema nodosum lesion, causing the lesion to look like a contusion (bruise)

- Erythema nodosum migrans (also known as subacute nodular migratory panniculitis), a rare form of chronic erythema nodosum characterized by asymmetrical nodules that are mildly tender and migrate over time.

Phakomatoses refers to a group of neuro-oculo-cutaneous syndromes or neurocutaneous disorders involving structures arising from the embryonic ectoderm. These multisystem disorders involve the ectodermal structures like central nervous system, skin and eyes. The lesions have a variable severity. However, it has been subsequently noted that mesodermal and endodermal tissues too are involved.

A number of genetic and acquired diseases come in this category and may affect one or more of these tissues. However, in some conditions, such as von Hippel-Lindau disease, ectodermal presentation is minimal.

Patients present with a slow-growing, painless, solitary mass, usually of the subcutaneous tissues. It is much less frequently noted in the intramuscular tissue. It is not uncommon for symptoms to be present for years.

Benign neoplasm with "BROWN FAT" is noted.

A hibernoma is a benign neoplasm of vestigial brown fat. The term was originally used by Gery in 1914.

The various types of vWD present with varying degrees of bleeding tendency, usually in the form of easy bruising, nosebleeds, and bleeding gums. Women may experience heavy menstrual periods and blood loss during childbirth.

Severe internal bleeding and bleeding into joints are uncommon in all but the most severe type, vWD type 3.

Type 1 vWD (60-80% of all vWD cases) is a quantitative defect which is heterozygous for the defective gene. It can arise from failure to secrete vWF into the circulation or from vWF being cleared more quickly than normal. Decreased levels of vWF are detected at 20-50% of normal, i.e. 20-50 IU.

Many patients are asymptomatic or may have mild symptoms and not have clearly impaired clotting, which might suggest a bleeding disorder. Often, the discovery of vWD occurs incidentally to other medical procedures requiring a blood work-up. Most cases of type 1 vWD are never diagnosed due to the asymptomatic or mild presentation of type I and most people usually end up leading a normal life free of complications, with many being unaware that they have the disorder.

Trouble may, however, arise in some patients in the form of bleeding following surgery (including dental procedures), noticeable easy bruising, or menorrhagia (heavy menstrual periods). The minority of cases of type 1 may present with severe hemorrhagic symptoms.

Ainhum (from Portuguese, pronounced "īn-yoom´", "i´num" or "ān´hum"; also known as dactylolysis spontanea) is a painful constriction of the base of the fifth toe frequently followed by bilateral spontaneous autoamputation a few years later.

The groove begins on the lower and internal side of the base of the fifth toe, usually according to the plantar-digital fold. The groove becomes gradually deeper and more circular. The rate of spread is variable, and the disease may progress to a full circle in a few months, or still be incomplete after years. In about 75 per cent both feet are affected, though not usually to the same degree. There is no case reported where it begins in any other toe than the fifth, while there is occasionally a groove on the fourth or third toe. The distal part of the toe swells and appears like a small “potato”. The swelling is due to lymphatic edema distal to the constriction. After a time crusts can appear in the groove which can be infected with staphylococcus.

While the groove becomes deeper, compression of tendons, vessels and nerves occurs. Bone is absorbed by pressure, without any evidence of infection. After a certain time all structures distal the stricture are reduced to an avascular cord. The toe’s connection to the foot becomes increasingly slender, and if it is not amputated, it spontaneously drops off without any bleeding. Normally it takes about five years for an autoamputation to occur.

Cole describes four stages of ainhum:

Pain is present in about 78% of cases. Slight pain is present in the earliest stage of ainhum, caused by pressure on the underlying nerves. Fracture of the phalanx or chronic sepsis is accompanied with severe pain.

The specific problems produced differ according to the particular abnormal synthesis involved. Common manifestations include ataxia; seizures; retinopathy; liver fibrosis; coagulopathies; failure to thrive; dysmorphic features ("e.g.," inverted nipples and subcutaneous fat pads; and strabismus. If an MRI is obtained, cerebellar atrophy and hypoplasia is a common finding.

Ocular abnormalities of CDG-Ia include: myopia, infantile esotropia, delayed visual maturation, low vision, optic disc pallor, and reduced rod function on electroretinography.

Three subtypes of CDG I (a,b,d) can cause congenital hyperinsulinism with hyperinsulinemic hypoglycemia in infancy.

The presentation of this condition includes a characteristic facies. The cardiac manifestations include patent ductus arteriosus, congenital hypertrophy of the left ventricle, and pericardial effusions.

Neurodevelopmental outcome appears normal, but obsessive traits and anxiety have been reported. It may also be associated with recurrent infections with low immunoglobulin levels and gastric bleeding, and additional possible associations include lymphoedema and heterochromia iridis.

Mutations in several genes have been associated with the traditional clinical syndromes, termed muscular dystrophy-dystroglycanopathies (MDDG). A new nomenclature based on clinical severity and genetic cause was recently proposed by OMIM. The severity classifications are A (severe), B (intermediate), and C (mild). The subtypes are numbered one to six according to the genetic cause, in the following order: (1) POMT1, (2) POMT2, (3) POMGNT1, (4) FKTN, (5) FKRP, and (6) LARGE.

Most common severe types include:

Children affected by nodding disease experience a complete and permanent stunting of growth. The growth of the brain is also stunted, leading to mental handicap. The disease is named for the characteristic, pathological nodding seizure, which often begins when the children begin to eat, or sometimes when they feel cold. These seizures are brief and halt after the children stop eating or when they feel warm again. Seizures in nodding disease span a wide range of severity. Neurotoxicologist Peter Spencer, who has investigated the disease, has stated that upon presentation with food, "one or two [children] will start nodding very rapidly in a continuous, pendulous nod. A nearby child may suddenly go into a tonic–clonic seizure, while others will freeze." Severe seizures can cause the child to collapse, leading to further injury. Sub-clinical seizures have been identified in electroencephalograms, and MRI scans have shown brain atrophy and damage to the hippocampus and glia cells.

It has been found that no seizures occur when victims are given an unfamiliar or non-traditional food, such as chocolate.

The clinical manifestations present at birth are generalized hypotonia, muscle weakness, developmental delay with mental retardation and occasional seizures. The congenital muscular dystrophy is characterized by hypoglycosylation of α-dystroglycan.

Those born with the disease also experience severe ocular and brain defects. Half of all children with WWS are born with encephalocele, which is a gap in the skull that will not seal. The meninges of the brain protrude through this gap due to the neural tube failing to close during development. A malformation of the a baby's cerebellum is often a sign of this disease.Common ocular issues associated with WWS are abnormally small eyes and retinal abnormalities cause by an underdeveloped light-sensitive area in the back of the eye.

The Mazzotti reaction, first described in 1948, is a symptom complex seen in patients after undergoing treatment of onchocerciasis with the medication diethylcarbamazine (DEC). Mazzotti reactions can be life-threatening, and are characterized by fever, urticaria, swollen and tender lymph nodes, tachycardia, hypotension, arthralgias, oedema, and abdominal pain that occur within seven days of treatment of microfilariasis. The Mazzotti reaction correlates with intensity of infection; however, there are probably multiple infection intensity-dependent mechanisms responsible for mediating this complex reaction.

The phenomenon is so common when DEC is used for the treatment of onchocerciasis that this drug is the basis of a skin patch test used to confirm that diagnosis. The drug patch is placed on the skin, and if the patient is infected with the microfilaria of "O. volvulus", localized pruritus and urticaria are seen at the application site.

A case of the Mazzotti reaction has been reported after presumptive treatment of schistosomiasis and strongyloidiasis with ivermectin, praziquantel and albendazole. The patient had complete resolution of symptoms after intravenous therapy with methylprednisolone.

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.

Cantú syndrome (hypertrychotic osteochondrodysplasia) is a rare condition characterized by hypertrichosis, osteochondrodysplasia, and cardiomegaly. Less than 50 cases have been described in the literature; they are associated with a mutation in the "ABCC9"-gene that codes for the ABCC9-protein.

Walker–Warburg syndrome (WWS), also called Warburg syndrome, Chemke syndrome, HARD syndrome (Hydrocephalus, Agyria and Retinal Dysplasia), Pagon syndrome, cerebroocular dysgenesis (COD) or cerebroocular dysplasia-muscular dystrophy syndrome (COD-MD), is a rare form of autosomal recessive congenital muscular dystrophy. It is associated with brain (lissencephaly, hydrocephalus, cerebellar malformations) and eye abnormalities. This condition has a worldwide distribution. The overall incidence is unknown but a survey in North-eastern Italy has reported an incidence rate of 1.2 per 100,000 live births. It is the most severe form of congenital muscular dystrophy with most children dying before the age of three years.

Nodding disease or nodding syndrome is a recent, little-known disease which emerged in Sudan in the 1960s. It is a mentally and physically disabling disease that only affects children, typically between the ages of 5 and 15. It is currently restricted to small regions in South Sudan, Tanzania, and northern Uganda. Prior to the South Sudan outbreaks and subsequent limited spread, the disease was first described in 1962 existing in secluded mountainous regions of Tanzania, although the connection between that disease and nodding syndrome was only made recently.

In documented BPF cases, the symptoms include high fever (101.3 degrees F or higher), nausea, vomiting, severe abdominal pain, septic shock, and ultimately death. A history of conjunctivitis 30 days prior to the onset of fever was also present in the documented BPF cases.

The physical presentation of children infected with BPF include purpuric skin lesions affecting mainly the face and extremities, cyanosis, rapid necrosis of soft tissue, particularly the hands, feet, nose, and ears. Analysis of the fatalities due to BPF showed hemorrhage in the skin, lungs, and adrenal glands. Histopathology showed hemorrhage, intravascular microthrombi and necrosis in the upper dermis, renal glomeruli, lungs, and hepatic sinusoids.