Alternative Names
scaly skin
Symptoms & Characteristics
The ichthyoses are a group of over 20 conditions that are characterized by dry, thickened, scaly or flaky skin on part or all of the body. In some of these conditions, additional abnormalities are also present. In most cases, ichthyosis is apparent at birth (congenital) or becomes apparent in early childhood.
The different ichthyoses are classified based on their clinical appearance (i.e. color and quality) and location of skin lesions, the presence of additional findings, inheritance pattern, and sometimes, genetic cause and/or histopathology. Some ichthyoses are mild, while others are severe. The severity of symptoms can even vary among affected individuals with the same form. Some of the more common forms of ichthyosis include:
- Ichthyosis vulgaris (Common ichthyosis)
- Harlequin type ichthyosis
- Epidermolytic hyperkeratosis and variants (such as ichthyosis hystrix, ichthyosis bullosa of Siemens, and bullous congenital ichthyosiform erythroderma)
- Lamellar ichthyosis (non-bullous congenital ichthyosiform erythroderma) and variants
- Erythrokeratoderma variablis (Mendes da Costa disease; Giroux-Barbeau syndrome)
Ichthyosis can also occur as part of a genetic syndrome. These syndromes are characterized by ichthyosis with additional physical and mental abnormalities. Some of the ichthyosis syndromes include:
Trichothiodystrophy (Tay syndrome) - characterized by brittle hair and nails, ichthyosis, and physical and mental retardation
Sjögren-Larsson syndrome - characterized by congenital ichthyosiform erythroderma, neurologic and eye abnormalities
Chanarin-Dorfman syndrome - a neural lipid storage disease with ichthyosis
Keratitis-ichthyosis-deafness syndrome (KID syndrome) - characterized by eye abnormalities, ichthyosis and deafness
CHILD syndrome - primarily characterized by congenital hemidysplasia with ichthyosiform erythroderma and limb defects
Conradi-Hünermann syndrome - a skeletal disorder with ichthyosis
Rud syndrome - characterized by ichthyosis and male hypogonadism (sex glands produce little or no hormones)
CHIME syndrome - characterized by oculo-colobomas (an eye abnormality), heart disease (congenital), ichthyosis, mental retardation and ear anomalies. The "E" can also stand for epilepsy.
Darier disease - characterized by wart-like blemishes on the body, nail abnormalities and less frequently, neurologic abnormalities
Netherton syndrome - characterized by ichthyosis linearis circumflexa; spiky, brittle hair with hair-shaft defects ("bamboo hair"); and a predisposition to allergies
Refsum disease (phytanic acid storage disease) - characterized by retinitis pigmentosa (a disorder in which there is progressive damage to retinal cells), deafness, problems with balance and coordination, weakness or numbness in peripheral extremities (peripheral neuropathy), ichthyosis, and cardiac arrhythmias (heartbeat abnormalities).
Treatment
Treatment for ichthyosis often includes topical oils, creams and ointments. Retinoids are also used for some forms. Early diagnosis, routine surveillance and treatment may help to manage some of the symptoms.
How Common Is It?
The combined incidence of all ichthyoses is unknown.
- Some ichthyoses are rare and have only been reported in a few families.
- Ichthyosis vulgaris is the most common form affecting 1 in 250 to 1 in 5,000 people.
Genetics & Inheritance
Ichthyoses and ichthyosis syndromes are typically genetic diseases. Over 20 causative genes have currently been identified. In some cases, mutations in the same gene cause different forms, while in other cases, mutations in different genes cause the same form. As such, one form may have multiple modes of genetic inheritance. Some people have late-onset, acquired ichthyosis that is not inherited and is a secondary manifestation of other diseases or conditions (such as cancer, infections and certain medications).
- Some ichthyoses (and associated syndromes) have autosomal dominant inheritance, which means that having a mutation in a single gene copy is sufficient to cause disease. An affected person has a 50% chance with each pregnancy to have an affected child. Some people with autosomal dominant ichthyoses have no history of the condition in their family, and their condition is caused by new (sporadic) mutation.
- Some ichthyoses (and associated syndromes) have autosomal recessive inheritance, which means that two mutations are necessary to cause disease, one from each parent. Both parents of an affected person are always both obligate carriers (each have only one mutation). Two carriers have a 25% chance with each pregnancy to have an affected child, but typically do not have symptoms themselves.
- Some ichthyoses have X-linked recessive inheritance. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation must be present in both copies of the gene to cause the disorder. As such, males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. In X-linked recessive inheritance, a female with one altered copy of the gene in each cell is called a carrier.
A genetic consultation with a trained genetic professional is important for a complete evaluation, accurate diagnosis, as well as discussion of the benefits and limitations of testing and recurrence risk.
Genetic Testing
Clinical genetic testing for some ichthyoses (and associated ichthyosis syndromes) may be available through an in person
genetic consultation for people who are considered at risk. Use our
find a genetic professional directory to locate a trained genetic professional in your area.
Support & More Information
More information can be found at:
Support can be found at: