People with the other type, NPS-type, do not have extensive palmoplantar hyperkeratosis, but do have hyperkeratosis on other areas of the body.Epidermolytic hyperkeratosis is part of a group of conditions called ichthyoses, which refers to the scaly skin seen in individuals with related disorders. However, in epidermolytic hyperkeratosis, the skin is thick but not scaly as in some of the other conditions in the group. http://ghr.nlm.nih.gov/condition/epidermolytic-hyperkeratosis

Genetics
It is possible to classify epidermolytic hyperkeratosis based upon palm and sole hyperkeratosis.This is a dominant genetic condition caused by mutations in the genes encoding the proteins keratin 1 or keratin 10. Keratin 1 is associated with the variants affecting the palms and soles. Keratin 10 is associated with the variants in which these are unaffected. Diagnosis
The condition can be diagnosed via exam that reveals; generalized redness; thick, generally dark, scales that tend to form parallel rows of spines or ridges, especially near large joints; the skin is fragile and blisters easily following trauma; extent of blistering and amount of scale is variable. Treatment
Oral retinoids have proven effective in treating this disorder. Depending on the side effects they may improve the quality of life. Examples are etretinate, acitretin, isotretinoin

Gene therapy
Gene therapy is really the only true therapy on the horizon for sufferers of EHK. Over the past 10 years since the first EHK mouse model was developed, many ideas have been discussed about how best to cure EHK. Back as far as 1994 researchers were discussing new promising ideas such as topical lotions that would deliver ribozymes in a liposome cream.
Epidermolytic ichthyosis (EI), also known as bullous epidermis ichthyosis (BEI), epidermolytic hyperkeratosis (EHK), bullous congenital ichthyosiform erythroderma (BCIE), bullous ichthyosiform erythroderma: 482  or bullous congenital ichthyosiform erythroderma Brocq, is a rare and severe form of ichthyosis this skin disease affects around 1 in 300,000 people. The condition is caused by a genetic mutation, so it cannot be completely cured without some form of gene therapy. While some research has been done into possible gene therapy treatments, the work hasnt yet been successfully developed to the stage where it can be routinely given to patients. The condition involves the clumping of keratin filaments. : 562

Presentation
Epidermolytic hyperkeratosis is a skin disorder that is present at birth. Affected babies may have very red skin (erythroderma) and severe blisters. Because newborns with this disorder are missing the protection provided by normal skin, they are at risk of becoming dehydrated and developing infections in the skin or throughout the body (sepsis). As affected individuals get older, blistering is less frequent, erythroderma becomes less evident, and the skin becomes thick (hyperkeratotic), especially over joints, on areas of skin that come into contact with each other, or on the scalp or neck. This thickened skin is usually darker than normal. Bacteria can grow in the thick skin, often causing a distinct odor. Epidermolytic hyperkeratosis can be categorized into two types :-

People with PS-type epidermolytic hyperkeratosis have thick skin on the palms of their hands and soles of their feet (palmoplantar or palm/sole hyperkeratosis) in addition to other areas of the body.