Last updated:
December 01, 2004
Years published: 1988, 1989, 1991, 1992, 1993, 1997, 2004
NORD gratefully acknowledges the members of the Medical and Scientific Advisory Board of the Foundation for Ichthyosis & Related Skin Types for assistance in the preparation of this report.
X-linked ichthyosis is a genetic skin disorder that affects males. It is an inborn error of metabolism characterized by a deficiency of the enzyme steroid sulfatase. Under normal conditions, this enzyme breaks down (metabolizes) cholesterol sulfate, a member of the chemical family of steroids. Cholesterol sulfate plays a role in maintaining the integrity of the skin. If steroid metabolism is interrupted and cholesterol sulfate accumulates in the skin cells, the skin cells stick together more strongly than usual. The normal shedding of dead skin cells is inhibited and the skin cells build up and clump into scales.
Boys with X-linked ichthyosis appear normal at birth. The skin symptoms generally appear within the first year of life. Brownish scales that adhere to the skin are among the first signs of the disorder. The back and legs are most frequently involved early. The face, scalp, palms and soles, and hollows of the elbows and knees are usually spared.
In about half of adult males, comma-shaped corneal opacities occur in the eyes (seen on exam by an ophthalmologist), but they do not interfere with vision. Symptoms can improve markedly in the summer months and warm humid climates.
A small percentage of males may experience undescended testes (crytpchordism). These men may be at increased risk for contracting malignancies of the testes.
Women who are carriers of X-linked ichthyosis and give birth to sons with the disorder may experience a delay in labor or failure of labor to initiate. The enzyme defect can cause a decrease in production of maternal estriol in late pregnancy, which may affect labor and delivery. Low serum estriol levels detected by prenatal screening suggest the presence of a fetus with X-linked ichthyosis.
X-linked recessive disorders are conditions that are coded on the X chromosome. Females have two X chromosomes; males have one X chromosome and one Y chromosome. Therefore, in females, the normal gene on one X chromosome can mask disease traits on the other X chromosome. Since males have only one X chromosome, if they inherit the gene for a disease present on the X they will express the disease. Men with X-linked disorders transmit the gene to all their daughters, who are carriers, but never to their sons. Women who are carriers of an X-linked disorder have a 50 percent chance of transmitting the carrier condition to their daughters and a 50 percent risk of transmitting the disease to their sons.
X-linked ichthyosis is a rare disorder affecting one in 6,000 males.
X-linked ichthyosis can be diagnosed before birth by amniocentesis or chorionic villus sampling. Low maternal estriol levels can suggest the presence of X-linked ichthyosis.
X-linked ichthyosis is treated by applying skin softening creams and lotions. This can be especially effective after bathing while the skin is still moist. X-linked ichthyosis responds relatively well to topical treatment with alpha-hydroxy acids, which accelerate the shedding of the dead skin cells. Cholesterol containing emollients may also improve the scaling. Alpha-hydroxy acids may sting the skin of babies and young children and should be used cautiously or in combination with another mild emollient product.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com
Oral retinoids, drugs derived from vitamin A, can be effective against some forms of ichthyosis. However, X-linked ichthyosis is not considered severe enough to warrant the use of oral retinoids.
JOURNAL ARTICLES
Elias, PM, Williams, ML. Enlightened Therapy of the Disorders of Cornification. Clinics in Dermatology. 2003; 21: 269 / 273.
DiGiovanna, JJ, Robinson-Bostom, L. Ichthyosis: etiology, diagnosis, and management. Am J Clin Dermatol. 2003;4: 81-95.
Zettersen, E, Man, MQ, Sato, J, et al. Recessive x-linked ichthyosis: role of cholesterol sulfate accumulation in the barrier abnormality. J Invest Dermatol. 1998; 111: 784-90.
Williams, ML, et al. Genetically Transmitted, Generalized Disorders of Cornification. The Ichthyoses. Dermatol Clin. January 1987; 5(1): 155-78.
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The Genetic and Rare Diseases Information Center (GARD) has information and resources for patients, caregivers, and families that may be helpful before and after diagnosis of this condition. GARD is a program of the National Center for Advancing Translational Sciences (NCATS), part of the National Institutes of Health (NIH).
View reportOrphanet has a summary about this condition that may include information on the diagnosis, care, and treatment as well as other resources. Some of the information and resources are available in languages other than English. The summary may include medical terms, so we encourage you to share and discuss this information with your doctor. Orphanet is the French National Institute for Health and Medical Research and the Health Programme of the European Union.
View reportOnline Mendelian Inheritance In Man (OMIM) has a summary of published research about this condition and includes references from the medical literature. The summary contains medical and scientific terms, so we encourage you to share and discuss this information with your doctor. OMIM is authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine.
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