About ichthyosis hystrix gravior

What is ichthyosis hystrix gravior?

Epidermal nevus syndromes (ENSs) are a group of rare complex disorders characterized by the presence of skin lesions known as epidermal nevi associated with additional extra-cutaneous abnormalities, most often affecting the brain, eye and skeletal systems. Epidermal nevi are overgrowths of structures and tissue of the epidermis, the outermost layer of the skin. The different types of epidermal nevi can vary in size, number, location, distribution and appearance. Neurological abnormalities that can be associated with ENSs can include seizures, cognitive impairment, developmental delays and paralysis of one side of the body (hemiparesis). Skeletal abnormalities can include abnormal curvature of the spine, malformation of the hip and abnormalities of the arms and legs (e.g., underdevelopment or absence or overgrowth of limbs). Ocular abnormalities may include cataracts, clouding (opacity) of the cornea or partial absence of tissue of the iris or retina (colobomas). Endocrine abnormalities such as vitamin D-resistant rickets have been associated with Schimmelpenning syndrome. The specific symptoms and severity of ENSs can vary greatly from one person to another. Most ENSs occur randomly for no apparent reason (sporadically), most likely due to a gene mutation that occurs after fertilization (postzygotic mutation) and is present in only some of the cells of the body (mosaic pattern).

The term "epidermal nevus syndrome" has generated significant controversy and confusion in the medical literature. Originally, the term was used to denote a disorder that was actually several different disorders erroneously grouped together. In the recent past, the term was used to denote a specific disorder now known as Schimmelpenning syndrome. However, the term epidermal nevus syndrome could be correctly applied to several different disorders. Therefore, the umbrella term "epidermal nevus syndromes" now represents a group of distinct disorders that have in common the presence of one of the various types of epidermal nevi. However, there is so far no general agreement how to classify the types of this diverse group of disorders, adding to the confusion within the medical literature. These disorders are quite different from one another and are not "variants" of each other as is sometimes mistakenly stated in the medical literature. In the future, as the genetic molecular basis of these disorders is better understood, the classification may change or expand. This report follows the classification from a review by Happle (J Am Acad Dermatol 2010).

Two other terms that have been used to describe ENSs are "organoid nevus syndrome" and "keratinocytic nevus syndrome". However, it is inappropriate to use these terms to denote a single disorder or interchangeably with epidermal nevus syndromes. Organoid nevus syndrome is a general term that could be applied to at least five different types of ENS. Keratinocytic nevus syndrome is a general term that could be applied to four different types of ENS.

NORD has individual reports on specific ENSs including Schimmelpenning syndrome, Proteus syndrome, and CHILD syndrome.

What are the symptoms for ichthyosis hystrix gravior?

Ichthyosis hystrix, Curth-Macklin type is characterized by patches of abnormally thick, hard skin that may appear almost anywhere on the body. Some clinicians describe the skin as “horn-like”. With treatment, the patches may be considerably reduced. Under examination by electron microscopy, numerous cells (keratinocytes) with two nuclei are found. Frequently, the nuclei are surrounded by shells of a primitive, precursor protein of the skin.

What are the causes for ichthyosis hystrix gravior?

The cause of ichthyosis hystrix, Curth Macklin type is a defect in the development of the precursor, structural protein (tonofilaments). The defect occurs as a result of a change (mutation) in the gene that produces (codes for) these proteins. The faulty gene has been mapped to chromosome 12q13.

Ichthyosis Hystrix, Curth-Macklin type is an inherited disorder, transmitted as an autosomal dominant trait.

Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 12q13” refers to band 13 on the long arm of chromosome 12. The numbered bands specify the location of the thousands of genes that are present on each chromosome.

Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.

All individuals carry a few abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child.

What are the treatments for ichthyosis hystrix gravior?

Ichthyosis hystrix, Curth-Macklin type is treated by applying skin softening (emollient) ointments, preferably plain petroleum jelly. This can be especially effective after bathing while the skin is still moist. Salicylic acid gel is another particularly effective ointment. The skin should be covered at night with an airtight, waterproof dressing when this ointment is used. Lactate lotion can also be an effective treatment for this disorder.

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