Lamellar ichthyosis
Lamellar ichthyosis is a skin disorder present from birth, characterized by large, dark, plate-like scales and a compromised skin barrier.
Overview
Infants with lamellar ichthyosis are typically born with a tight, clear sheath called a collodion membrane. Once this peels off during the first few weeks of life, the characteristic scaly skin becomes apparent. The condition affects the outermost layer of the skin, the epidermis, impairing the body's ability to regulate temperature, retain water, and resist infections.
Symptoms
- Skin: Large, dark, plate-like scales covering most of the body.
- Facial features: Eyelids and lips that are turned outward.
- Additional features: Hair loss (alopecia), abnormally formed fingernails and toenails (nail dystrophy), decreased ability to sweat (hypohidrosis), heat sensitivity, and thickening of the skin on the palms and soles (keratoderma).
- Infant complications: Risk of infection, dehydration, and respiratory problems.
Causes
Mutations in several genes can cause the condition, most notably the TGM1 gene, which accounts for approximately 90 percent of cases. The TGM1 gene provides instructions for the enzyme transglutaminase 1, which is essential for forming the cornified cell envelope—a protective barrier for skin cells. When this enzyme is absent or reduced, the skin cannot form this barrier properly.
Inheritance
Lamellar ichthyosis is inherited in an autosomal recessive pattern. This means both copies of the gene in each cell must have mutations for the condition to occur. Parents of an affected individual each carry one copy of the mutated gene but typically do not exhibit symptoms of the disorder.