301-519-2100 • FAX 301-519-2892 • 207 PERRY PARKWAY GAITHERSBURG, MD 20877
SEARCH
Harlequin Ichthyosis (HI)
Lamellar ichthyosis, type 2 (LI-2)
ABCA12 (ATP binding cassette (ABC) transporter, subfamily A, member 12)
Harlequin ichthyosis (HI) and lamellar ichthyosis, type 2 (LI2) are different types of congenital recessive ichthyosis (CRI). Harlequin ichthyosis is a life-threatening and often fatal disorder. Infants are born prematurely encased in a thick, armor-like cast that severely restricts movements and deforms facial features and distal extremities. Various abnormalities of inner organs have also been reported. Postnatal complications include respiratory distress, dehydration, feeding problems and bacterial infections. In surviving children, the armor-like plates are shed and replaced by intense redness and whitish scale covering the entire body, resembling severe non-bullous congenital ichthyosiform erythroderma (NBCIE). There is ectropium and eclabium (out-turning of the eyelids and mouth) due to tautness of the skin, alopecia, thickening of the skin on palms and soles, heat intolerance and growth delay. Harlequin ichthyosis is very rare. Most patients have autosomal recessive mutations in the ABCA12 gene on chromosome 2q34 that completely prevent the production of this cellular lipid transport protein.
In lamellar ichthyosis, babies are born with a taut collodion membrane causing ectropium and eclabium. After the membrane is shed, the patient develops white or brown, plate-like scale with no or little redness over the entire body. The majority of patients with LI have mutations in the transglutaminase-1 gene (TGM1) and it is recommended that this gene be tested first. (
Click here to see the listing for lamellar ichthyosis
). Some but not all LI patients without TGM1 mutations, especially those of Northern African decent, may have mutations of the ABCA12 gene.
In HI, mutations of ABCA12 are identified by complete sequence analysis of the entire coding region of the gene (53 exons). In LI patients in whom TGM1 mutations have been ruled out, sequence analysis is done for 5 exons (exon 28-32) containing all mutations that have been reported in LI to date. Analysis is performed from a peripheral blood sample in EDTA or buccal (cheek) swabs. Carrier testing of relatives and prenatal diagnosis in at-risk pregnancies is available once the mutations in a family have been defined.
Information Sheet, including prices and CPT codes
Consent Document
Genetic Test Sample Submission Form (Test Requisition Form) including Payment Options
ichthyosis, CRI, lamellar, erythroderma, erythrodermic, congenital ichthyosiform erythroderma, NBCIE, collodion membrane, ABCA12, ABC transporter, TGM1, lipids, fatal, premature, Harlequin fetus, ectropium, eclabium, infections, respiratory distress
© 2000 - 2010 GeneDx. All rights reserved.
