Microlissencephaly Type B or Barth microlissencephaly syndrome: is a microlissencephaly with thick cortex, severe cerebellar and brainstem hypoplasia. The Barth-type of MLIS is the most severe of all the known lissencephaly syndromes.

This phenotype consists of polyhydramnios (probably due to poor fetal swallowing), severe congenital microcephaly, weak respiratory effort, and survival for only a few hours or days. Barth described two siblings with this type as having a very low brainweight, wide ventricles, a very thin neopallium, absent corpus callosum and absent olfactory nerve.

Microlissencephaly with mildly to moderately thick (6–8 mm) cortex, callosal agenesis

The initial description of AGS suggested that the disease was always severe, and was associated with unremitting neurological decline, resulting in death in childhood. As more cases have been identified, it has become apparent that this is not necessarily the case, with many patients now considered to demonstrate an apparently stable clinical picture, alive in their 4th decade. Moreover, rare individuals with pathogenic mutations in the AGS-related genes can be minimally affected (perhaps only with chilblains) and are in mainstream education, and even affected siblings within a family can show marked differences in severity.

In about ten percent of cases, AGS presents at or soon after birth (i.e. in the neonatal period). This presentation of the disease is characterized by microcephaly, neonatal seizures, poor feeding, jitteriness, cerebral calcifications (accumulation of calcium deposits in the brain), white matter abnormalities, and cerebral atrophy; thus indicating that the disease process became active before birth i.e. "in utero". These infants can have hepatosplenomegaly and thrombocytopaenia, very much like cases of transplacental viral infection. About one third of such early presenting cases, most frequently in association with mutations in "TREX1", die in early childhood.

Otherwise the majority of AGS cases present in early infancy, sometimes after an apparently normal period of development. During the first few months after birth, these children develop features of an encephalopathy with irritability, persistent crying, feeding difficulties, an intermittent fever (without obvious infection), and abnormal neurology with disturbed tone, dystonia, an exaggerated startle response, and sometimes seizures.

Glaucoma can be present at birth, or develop later. Many children retain apparently normal vision, although a significant number are cortically blind. Hearing is almost invariably normal. Over time, up to 40% of patients develop so-called chilblain lesions, most typically on the toes and fingers and occasionally also involving the ears. They are usually worse in the winter.

The acronym CHILD stands for the symptoms of the syndrome:

- CH = Congenital Hemidysplasia—One side of the body, most of the time the right side, is poorly developed. The right ribs, neck, vertebrae, etc. may be underdeveloped and the internal organs may be affected.

- I - Ichthyosiform Erythroderma—At birth or shortly after birth, there are red, inflamed patches (erythroderma), and flaky scales (ichthyosis) on the side of the body that is affected. Hair loss on the same side may also be possible.

- LD - limb defects—Fingers on the hand or toes on the foot of the affected side may be missing. An arm or leg may also be shortened or even missing.

Congenital hemidysplasia with ichthyosiform erythroderma and limb defects (also known as "CHILD syndrome") is a genetic disorder with onset at birth seen almost exclusively in females. The disorder is related to CPDX2, and also has skin and skeletal abnormalities, distinguished by a sharp midline demarcation of the ichthyosis with minimal linear or segmental contralateral involvement.

The acronym was introduced in 1980.

Aicardi–Goutières syndrome (AGS), which is completely distinct from the similarly named Aicardi syndrome, is a rare, usually early onset childhood, inflammatory disorder most typically affecting the brain and the skin (neurodevelopmental disorder). The majority of affected individuals experience significant intellectual and physical problems, although this is not always the case. The clinical features of AGS can mimic those of "in utero" acquired infection, and some characteristics of the condition also overlap with the autoimmune disease systemic lupus erythematosus (SLE). Following an original description of eight cases in 1984, the condition was first referred to as 'Aicardi–Goutières syndrome' (AGS) in 1992, and the first international meeting on AGS was held in Pavia, Italy, in 2001.

AGS can occur due to mutations in any one of a number of different genes, of which seven have been identified to date, namely: TREX1, RNASEH2A, RNASEH2B, RNASEH2C (which together encode the Ribonuclease H2 enzyme complex), SAMHD1, ADAR1, and IFIH1 (coding for MDA5). This neurological disease occurs in all populations worldwide, although it is almost certainly under-diagnosed. To date (2014) at least 400 cases of AGS are known.

Patients typically present with low frequency hearing loss detectable via an audiogram. Headaches are frequently present in addition to roaring tinnitus and often some degree of paranoia. Partial vision loss is often present and caused by branch retinal artery occlusions. The presence of refractile or non-refractile yellow Gass plaques in the retinal arterioles is near pathognomonic for the disease. Fluorescein angiography may demonstrate leakage in areas remote from the retinal infarctions.

In a recent analysis (Susac et al., 2003), MRI images from 27 patients fulfilling the diagnostic criteria of Susac's syndrome were reviewed. Multifocal supratentorial lesions were present in all patients. Most lesions were small (3 to 7 mm), though some were larger than 7 mm. All 27 patients had corpus callosum lesions. These all had a punched-out appearance on follow up MRI. Though most commonly involving white matter, many patients also had lesions in deep grey matter structures, as well as leptomeningeal enhancement. Multiple sclerosis (MS) and acute disseminated encephalomyelitis (ADEM) can mimic the MRI changes seen in patients with Susac's syndrome. However, the callosal lesions in Susac's syndrome are centrally located. In comparison, patients with MS and ADEM typically have lesions involving the undersurface of the corpus callosum. Deep gray matter involvement commonly occurs in ADEM but is very rare in MS. Leptomeningeal involvement is not typical of either MS or ADEM. What this means is that if 10 lesions are found in the brain of an MS patient, a lesion may be found in the corpus callosum. If you have 10 lesions in a Susac patient, more than half will be in the corpus callosum.

A concern about this illness is that it mimics multiple sclerosis when looking at the vision loss and brain lesions. If close attention is not paid to the retina of a patient with vision loss and brain lesions, their symptoms may be mistaken for MS instead of Susac's syndrome. This may account for the low prevalence of the illness. There is also a pathological similarity between the endotheliopathy in Susac's syndrome with that seen in juvenile dermatomyositis.

KWE is characterized by a number of anomalies affecting the skin. Erythema causes redness of the skin, which is generally associated with inflammation and irritation. Including erythema and hyperkeratosis (thickening of the stratum corneum), naturally occurring keratolytic peeling and scaling, with increased manifestation in winter, are prevailing features of the disorder.

Erythema in KWE has been attributed to necrobiosis (cellular death) within the malpighian layer (the innermost layer of the epidermis). Peeling and scaling are caused by spreading dissection of the stratum corneum, correlating to the underlying necrobiosis.

The effects of KWE appear intermittently as patches on the skin of the palms and soles, with these patches appearing on the limbs, buttocks and torso in severe cases. Facial lesions of this type have also been reported with the disorder, though this is considered to be an extremely rare occurrence.

Onset and cyclical recurrence of KWE have shown to be associated with the arrival of winter, or winter-like weather. Worsening of symptoms during this time may be considered as an indicator of recurrent onset in patients known to have the disorder, and age of initial onset can be from early childhood to young adulthood, with attenuation of symptoms sometimes happening after age 30. Patients first exhibiting the disorder at a younger age may also experience worsened symptoms. Currently, no specific correlating factor or reason for winter-related manifestation has been established, though the coldness and dryer air common to winter conditions may be suspect. Winter onset is, however, considered to be a distinguishing feature of KWE among other erythematic skin disorders.

When peeling of skin occurs, the newly exposed layer of skin underneath is moist, raw and very sensitive. While this may result in minor discomfort and inconvenience, in severe cases of KWE where large areas of raw skin are present, it is often life-altering and debilitating.

KWE is inherited in an autosomal dominant manner. This means that the defective gene responsible for the disorder is located on an autosome (chromosome 8 is an autosome), and one copy of the defective gene is sufficient to cause the disorder when inherited from a parent who also has the disorder.

KWE can begin as a spontaneous mutation, first appearing in an individual with no previous family history of the disorder. This may be due to a genetic predisposition for the disorder, possibly connected to the Oudtshoorn ancestral line.

Keratolytic Winter erythema ( Oudtshoorn disease and Oudtshoorn skin, }is a rare autosomal dominant skin disease of unknown cause which causes redness and peeling of the skin on the palms and soles. Onset, increased prominence and severity usually occurs during winter. It is a type of genodermatosis.

The name "Oudtshoorn skin" derives from the town of Oudtshoorn in the Western Cape province of South Africa, where the disorder was first described. It is one of several genetic disorders known to be highly prevalent among the Afrikaner population.

Asymmetric periflexural exanthem of childhood (APEC) (also known as "unilateral laterothoracic exanthem") is a rare, self-limited and spontaneously resolving skin rash of the exanthem type with unknown cause that occurs in children. It occurs primarily in the late winter and early spring, most common in Europe, and affecting girls more often than boys.

It is probably viral, but no virus has yet been associated with the condition.

A number of conditions may cause the appearance of livedo reticularis:

- Cutis marmorata telangiectatica congenita, a rare congenital condition

- Sneddon syndrome – association of livedoid vasculitis and systemic vascular disorders, such as strokes, due to underlying genetic cause

- Idiopathic livedo reticularis – the most common form of livedo reticularis, completely benign condition of unknown cause affecting mostly young women during the winter: It is a lacy purple appearance of skin in extremities due to sluggish venous blood flow. It may be mild, but ulceration may occur later in the summer.

- Secondary livedo reticularis:

- Vasculitis autoimmune conditions:

- Livedoid vasculitis – with painful ulceration occurring in the lower legs

- Polyarteritis nodosa

- Systemic lupus erythematosus

- Dermatomyositis

- Rheumatoid arthritis

- Lymphoma

- Pancreatitis

- Chronic pancreatitis

- Tuberculosis

- Drug-related:

- Adderall (side effect)

- Amantadine (side effect)

- Bromocriptine (side effect)

- Beta IFN treatment, "i.e." in multiple sclerosis

- Livedo reticularis associated with rasagiline

- Methylphenidate and dextroamphetamine-induced peripheral vasculopathy

- Gefitinib

- Obstruction of capillaries:

- Cryoglobulinaemia – proteins in the blood that clump together in cold conditions

- Antiphospholipid syndrome due to small blood clots

- Hypercalcaemia (raised blood calcium levels which may be deposited in the capillaries)

- Haematological disorders of polycythaemia rubra vera or thrombocytosis (excessive red cells or platelets)

- Infections (syphilis, tuberculosis, Lyme disease)

- Associated with acute renal failure due to cholesterol emboli status after cardiac catheterization

- Arteriosclerosis (cholesterol emboli) and homocystinuria (due to Chromosome 21 autosomal recessive Cystathionine beta synthase deficiency)

- Intra-arterial injection (especially in drug addicts)

- Ehlers-Danlos syndrome – connective tissue disorder, often with many secondary conditions, may be present in all types

- Pheochromocytoma

- Livedoid vasculopathy and its association with factor V Leiden mutation

- FILS syndrome (polymerase ε1 mutation in a human syndrome with facial dysmorphism, immunodeficiency, livedo, and short stature)

- Primary hyperoxaluria, oxalosis (oxalate vasculopathy)

- Cytomegalovirus infection (very rare clinical form, presenting with persistent fever and livedo reticularis on the extremities and cutaneous necrotizing vasculitis of the toes)

- Generalized livedo reticularis induced by silicone implants for soft tissue augmentation

- As a rare skin finding in children with Down syndrome

- Idiopathic livedo reticularis with polyclonal IgM hypergammopathy

- CO angiography (rare, reported case)

- A less common skin lesion of Churg-Strauss syndrome

- Erythema nodosum-like cutaneous lesions of sarcoidosis showing livedoid changes in a patient with sarcoidosis and Sjögren's syndrome

- Livedo vasculopathy associated with IgM antiphosphatidylserine-prothrombin complex antibody

- Livedo vasculopathy associated with plasminogen activator inhibitor-1 promoter homozygosity and prothrombin G20210A heterozygosity

- As a first sign of metastatic breast carcinoma (very rare)

- Livedo reticularis associated with renal cell carcinoma (rare)

- Buerger's disease (as an initial symptom)

- As a rare manifestation of Graves hyperthyroidism

- Associated with pernicious anaemia

- Moyamoya disease (a rare, chronic cerebrovascular occlusive disease of unknown cause, characterized by progressive stenosis of the arteries of the circle of Willis leading to an abnormal capillary network and resultant ischemic strokes or cerebral hemorrhages)

- Associated with the use of a midline catheter

- Familial primary cryofibrinogenemia.

Livedo reticularis is a common skin finding consisting of a mottled reticulated vascular pattern that appears as a lace-like purplish discoloration of the skin. The discoloration is caused by swelling of the venules owing to obstruction of capillaries by small blood clots. The blood clots in the small blood vessels can be a secondary effect of a condition that increases a person's risk of forming blood clots, including a wide array of pathological and nonpathological conditions . Examples include hyperlipidemia, microvascular hematological or anemia states, nutritional deficiencies, hyper- and autoimmune diseases, and drugs/toxins.

The condition may be normal or related to more severe underlying pathology. Its differential diagnosis is broadly divided into possible blood diseases, autoimmune (rheumatologic) diseases, cardiovascular diseases, cancers, and endocrine disorders. It can usually (in 80% of cases) be diagnosed by biopsy.

It may be aggravated by exposure to cold, and occurs most often in the lower extremities.

The condition's name derives from the Latin "livere" meaning bluish and "reticular" which refers to the net-like appearance.

Polar T syndrome is a condition found in polar explorers, caused by a reduction in levels of the thyroid hormone T. Its effects include forgetfulness, cognitive impairment and mood disturbances. It can exhibit itself in a fugue state known as the "Antarctic stare".

It is regarded as one of the contributory causes of winter-over syndrome.

Most women with this condition present in third trimester with itching without a rash. Typically, the itching is localized to the palms of the hands and soles of the feet but can be anywhere on the body.

Hallmarks of ICP include the following symptoms:

Most common:

- Itching, in particular but not limited to that of the palms of the hands and soles of the feet, without presence of a rash

- Itching that increases in the evening

- Itching that does not respond favorably to anti-histamines or other anti-itch remedies

- Often, elevated LFT results as well as serum bile acid counts

Less common:

- Darker urine

- Lighter stools

- Increased clotting time (due to possibly associated vitamin K deficiency)

- Fatigue

- Increased nausea

- Decrease in appetite

- Jaundice

- Upper right quadrant pain

It is important to note that not all ICP sufferers have all of the above symptoms. For example, Jaundice only occurs in relatively small subset of cases, and in some cases abnormal lab results were not seen until 15 weeks or more after the onset of symptoms.

The condition is usually seen in athletic individuals typically between 10–14 years of age. Following a strain or partial rupture of patellar ligament the patient develops a traction ‘tendinitis’ characterized by pain and point tenderness at the inferior (lower) pole of the patella associated with focal swelling.

Children with cerebral palsy are particularly prone to SLJ 4.

Livedoid vasculopathy (also known as "livedoid vasculitis", "livedo reticularis with summer/winter ulceration" and "segmental hyalinizing vasculitis") is a chronic cutaneous disease seen predominantly in young to middle-aged women. One synonym used to describe its features is "Painful purpuric ulcers with pattern of the lower extremities" (PURPLE).

It can be divided into a primary (or idiopathic) form and a secondary form, which has been associated with a number of diseases, including chronic venous hypertension and varicosities.

The winter-over syndrome is a condition found in individuals who "winter-over" throughout the Antarctic (or Arctic) winter. It has been observed in inhabitants of research stations in Antarctica, as well as in polar bases such as Thule, Alert and Eureka. It consists of a variety of behavioral and medical disturbances, including irritability, depression, insomnia, absentmindedness, aggressive behavior, and irritable bowel syndrome.

Possible contributing causes of winter-over syndrome include stress, social isolation, subsyndromal seasonal affective disorder and polar T syndrome.

Asplenia refers to the absence of normal spleen function and is associated with some serious infection risks. Hyposplenism is used to describe reduced ('hypo-') splenic functioning, but not as severely affected as with asplenism.

In an effort to preserve some of the spleen's protective roles, attempts are now often made to preserve a small part of the spleen when performing either surgical subtotal (partial) splenectomy, or partial splenic embolization.

This may be particularly important in poorer countries where protective measures for patients with asplenia are not available.

However, it has been advised that preoperative vaccination is advisable until the remnant splenic tissue can reestablish its function.

Sinding-Larsen and Johansson syndrome, named after Swedish surgeon Sven Christian Johansson (1880-1959), and Christian Magnus Falsen Sinding-Larsen (1866-1930), a Norwegian physician, is an analogous condition to Osgood–Schlatter disease involving the patellar tendon and the lower margin of the patella bone, instead of the upper margin of the tibia, as is the case in Osgood-Schlatter. This variant was discovered in 1908, during a winter indoor Olympic qualifier event in Scandinavia. Sever's disease is a similar condition affecting the heel.

This condition called Sinding-Larsen and Johansson syndrome was described independently by Sinding-Larsen in 1921 and Johansson in 1922.

Intrahepatic cholestasis of pregnancy (ICP), also known as obstetric cholestasis, cholestasis of pregnancy, jaundice of pregnancy, and prurigo gravidarum, is a medical condition in which cholestasis occurs during pregnancy. It typically presents with troublesome itching and can lead to complications for both mother and fetus.

Pruritus (itching) has long been considered to be a common symptom of pregnancy. The vast majority of times, itching is a minor annoyance caused by changes to the skin, especially that of the abdomen. However, there are instances when itching is a symptom of ICP. This is usually most intense on the palms of the hands, and the soles of the feet, but can be widespread.

ICP occurs most commonly in the third trimester, but can begin at any time during the pregnancy.

Juvenile plantar dermatosis (also known as "Atopic winter feet," "Dermatitis plantaris sicca," "Forefoot dermatitis," "Moon-boot foot syndrome," and "Sweaty sock dermatitis") is a condition usually seen in children between the ages of 3 and 14, and involves the cracking and peeling of weight bearing areas of the soles of the feet. One of the earliest descriptions was made by British dermatologist Darrell Wilkinson.

The dry scaling appearance is most noticeable during the winter as a result of dry air inside people's homes. During the summer, tanning of the surrounding normal skin makes the pale patches of pityriasis alba more prominent.

Individual lesions develop through 3 stages and sometimes are itchy:

1. Raised and red – although the redness is often mild and not noticed by parents

2. Raised and pale

3. Smooth flat pale patches

Lesions are round or oval raised or flat, of 0.5–2 cm in size although may be larger if they occur on the body (up to 4 cm), and usually number from 4 or 5 to over 20. The patches are dry with very fine scales. They most commonly occur on the face (cheeks), but in 20% appear also on the upper arms, neck, or shoulders.

The diagnostic differential should consider tinea and vitiligo amongst other causative factors.

Pityriasis alba is a common skin condition mostly occurring in children and usually seen as dry, fine-scaled, pale patches on the face. It is self-limiting and usually only requires use of moisturizer creams.

The condition is so named for the fine scaly appearance initially present (pityriasis) and the pallor of the patches that develop (while "alba" is Latin for white, the patches in this condition are not totally depigmented).