Lamellar ichthyosis (LI) is an autosomal recessive disorder that is apparent at birth and is present throughout life. The newborn is born encased in a collodion membrane that sheds within 10-14 days. The shedding of the membrane reveals generalized scaling with variable redness of the skin. The scaling may be fine or platelike, resembling fish skin. Although the disorder is not life threatening, it is quite disfiguring and causes considerable psychological stress to affected patients. 
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Patients with lamellar ichthyosis have accelerated epidermal turnover with proliferative hyperkeratosis, in contrast to retention hyperkeratosis. This involves a mutation in the gene for transglutaminase 1 (TGM1). There are at least 14 identified different TGM1 mutations.  The transglutaminase 1 enzyme is involved in the formation of the cornified cell envelope. The formation of the cornified cell envelope is an essential scaffold upon which normal intercellular lipid layer formation in the stratum corneum occurs. Thus, mutations in the TGM1 secondarily cause defects in the intercellular lipid layers in the stratum corneum, leading to defective barrier function of the stratum corneum and to the ichthyotic phenotype seen in lamellar ichthyosis patients and in transglutaminase 1 knockout mice. How much a defective cornified cell envelope alone contributes to the barrier abnormality in ichthyoses remains unclear. 
To date, six genes for lamellar ichthyosis have been localized and 5 of them identified, as follows  :
Prevalence is less than 1 case per 300,000 individuals.
Lamellar ichthyosis affects all populations.
Incidence in males and females is equal.
The disease is present at birth and continues throughout life.
A rare phenotype of lamellar ichthyosis has been described in South Africa. The term bathing-suit ichthyosis describes the characteristic distribution of the lesions, which involve the trunk, the proximal parts of the upper limbs, the scalp, and the neck, with sparing of the central face and extremities. This form of lamellar ichthyosis is caused by a homozygous missense mutation in TGM1. [5, 6]
Patients with lamellar ichthyosis have normal life spans.
In the neonatal period, following the shedding of the collodion membrane, the newborn is at risk for secondary sepsis and hypernatremic dehydration.
As the child ages, the hyperkeratosis can interfere with normal sweat gland function, which can predispose to heat intolerance and possible heat shock. Ectropion may result in the inability to fully close the eyelids and can cause exposure keratitis.
External auditory canal stenosis and tympanic membrane blunting may result in a conductive hearing loss. Osseointegrated hearing devices may effectively bypass this hearing defect.
Less common associations include orthopedic abnormalities such as genu valgum, other ocular problems such as corneal perforation, and rickets. 
The family should be aware of these patient and family support groups:
National Registry for Ichthyosis and Related Disorders, University of Washington, Dermatology Department, Rm. BB1353, Box 356524, 1959 NE Pacific St., Seattle, WA 98195-6524; telephone: (206) 616-3179 or (800) 595-1265, www.skinregistry.org, email: firstname.lastname@example.org
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