Ellis–Van Creveld syndrome (also called  mesoectodermal dysplasia but see Nomenclature section below) is a rare genetic disorder of the skeletal dysplasia type. Signs and symptoms
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). Genetics
Ellis–Van Creveld syndrome often is the result of founder effects in isolated human populations, such as the Amish and some small island inhabitants. Although relatively rare, this disorder does occur with higher incidence within founder-effect populations due to lack of genetic variability. Observation of the inheritance pattern has illustrated that the disease is autosomal recessive, meaning that both parents have to carry the gene in order for an individual to be affected by the disorder.Ellis–Van Creveld syndrome is caused by a mutation in the EVC gene, as well as by a mutation in a nonhomologous gene, EVC2, located close to the EVC gene in a head-to-head configuration. The gene was identified by positional cloning. The EVC gene maps to the chromosome 4 short arm (4p16). The function of a healthy EVC gene is not well understood at this time. Relation to other rare disorders:  genetic ciliopathy
Until recently, the medical literature did not indicate a connection among many genetic disorders, both genetic syndromes and genetic diseases, that are now being found to be related.
First degree
First degree frostbite is superficial, surface skin damage that is usually not permanent. Early on, the primary symptom is loss of feeling in the skin. In the affected areas, the skin is numb, and possibly swollen, with a reddened border. In the weeks after injury, the skins surface may slough off. Second degree
In second degree frostbite, the skin develops clear blisters early on, and the skins surface hardens. In the weeks after injury, this hardened, blistered skin dries, blackens, and peels. At this stage, lasting cold sensitivity and numbness can develop. Third degree
In third degree frostbite, the layers of tissue below the skin freeze. Symptoms include blood blisters and "blue-grey discoloration of the skin". In the weeks after injury, pain persists and a blackened crust (eschar) develops. There can be longterm ulceration and damage to growth plates. Fourth degree
In fourth degree frostbite, structures below the skin are involved like muscles, tendon, and bone. Early symptoms include a colorless appearance of the skin, a hard texture, and painless rewarming. Later, the skin becomes black and mummified. The amount of permanent damage can take one month or more to determine. Autoamputation can occur after two months. Causes
Risk factors
The major risk factor for frostbite is exposure to cold through geography, occupation and/or recreation. Inadequate clothing and shelter are major risk factors. Frostbite is more likely when the bodys ability to produce or retain heat is impaired. Physical, behavioral, and environmental factors can all contribute to the development of frostbite.