Date: 06/05/2014

Announcement from GeneDX:  New genetic test,  congenital ichthyosis XomeDxSlice, to screen 38 different genes for mutations causing congenital ichthyosis

Congenital ichthyosis and related disorders of cornification of the skin are a clinically and genetically very heterogeneous group of genetic disorders. It can be challenging, if not impossible to predict the disease-causing gene in a patient with congenital ichthyosis based on initial presentation and clinical features alone. It is often necessary to perform diagnostic tests requiring an invasive skin biopsy and/or genetic analysis of multiple genes (concurrently or as reflex tests) to pinpoint the underlying genetic cause. Moreover, genetic testing is currently not available for a number of newly discovered ichthyosis genes.

To overcome these limitations of traditional gene sequencing, GeneDX has developed a new test based on whole exome capture (WEC), Next Generation sequencing (NGS), andconcurrent, targeted analysis of 38 genes associated with congenital ichthyosis or related disorders of cornification. The test could be used for a work-up of newborns with collodion membrane or harlequin ichthyosis, or patients with suspected epidermolytic ichthyosis, KID, Netherton, Sjögren-Larsson, ichthyosis-prematurity syndrome, neutral lipid storage disease and other skin disorders.

What is different about this test?  The test is based on WEC and NGS, and analyzes 38 different disease genes. Therefore, it is a much more comprehensive test, and provides substantial savings in both cost and time compared to traditional sequencing of multiple genes. However, Congenital Ichthyosis XomeDxSlice has a somewhat lower technical sensitivity (97%) compared to Sanger sequencing (>99%), which means in about 3% of tests performed, a mutation may be present, but the test will not detect it.

How to order this test?  Those individuals with ichthyosis seeking a molecular diagnosis should consult with their primary care doctor, pediatrician, dermatologist or geneticist. Test information and material can be printed from:                        If the primary care physician is not familiar with genetic testing and how to order a genetic test, it is beneficial to involve a genetic counselor, who can coordinate testing, explain the test and procedure in advance, and obtain consent for testing. One can find a genetic counselor by using this website link from the National Society of Genetic Counselors:

What does the test cost?  This is a common question regarding genetic testing. This depends on the type of medical insurance one carries, and if testing is ordered through a referral lab.  For further information, please submit any billing related questions to

One word of caution: This test will not find all the answers.  Some types of ichthyosis are not included, such as the very common ichthyosis vulgaris. This test also does not target a variety of other genetic skin disorders with hyperkeratosis, such as several forms of palmoplantar keratoderma or Darier disease.  Hence one should always first discuss the situation with a physician or genetic counselor, to see if this test is appropriate.

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