Ichthyosis x-linked recessiveQ80.1

X-linked recessive ichthyosis due to mutation in the steroid sulfatase gene (almost exclusively affecting the male sex). Rarely collodion skin at birth. Disease symptomatology is often present at birth or breaks out in the first months of life. The course is progressive until puberty and then remains stationary.

Worldwide & panethnic distribution. Incidence: 1/2000-6,000 male births. Prevalence in the general population is 1:4,000.

X-linked recessive mutations of the steroid sulfatase gene(STS gene; gene locus: Xp22.3). The genetic defect is 90% a deletion of the STS gene. This leads to a deficiency of microsomal steroid sulfatase, an enzyme that removes sulfate residues, including cholesterol sulfate and dehydroepinandrosterone. This leads to an increase in cholesterol sulphate, e.g. in keratinocytes, fibroblasts and leukocytes. The gene mutation can also extend to neighboring genes, which can lead to more complex disease associations.

• XRI + Kallmann syndrome
• XRI + X-linked recessive form of chondrodysplasia punctata
• XRI+ Recessive epidermolysis bullosa dystrophica (Hernández-Martín A et al. 2010)
• XRI + cryptorchidism (20% of cases)
• XRI + ADHD (20-30% of cases of XRI patients)
• XRI + autism (25% of cases)

X-linked ichthyosis is frequently associated with atopic diseases(bronchial asthma, allergic rhinitis, allergic conjunctivitis, atopic dermatitis). The investigations revealed a microdeletion of the steroid sulphatase region (Xp22.3), an increased total IgE value and polysensitization. It appears that steroid sulfatase deficiency in ichthyosis plays a role in the development of atopic diseases (Harangi F et al. 2000).

Onset in infancy with relatively light-colored scaling, initially on the lower legs. Compared to autosomal dominant ichthyosis vulgaris, the scaling is more pronounced, the skin scales themselves are larger and relatively firm. With increasing age, the scaling becomes darker, more adherent and is later dirty gray, thick and coarse-fielded, rhombic. As with the autosomal dominant form, the large body flexion creases are usually omitted. The palms of the hands and soles of the feet show no increased line pattern. Comma-shaped, deep-seated corneal opacities are common. The accumulation of birth complications is also striking. Furthermore, around one in five of those affected have undescended testicles (cryptorchidism).

X-linked ichthyosis is often associated with atopic diseases(bronchial asthma, allergic rhinitis, allergic conjunctivitis, atopic dermatitis). The investigations revealed a microdeletion of the steroid sulphatase region (Xp22.3), an increased total IgE value and polysensitization. It appears that steroid sulfatase deficiency in ichthyosis plays a role in the development of atopic diseases (Harangi F et al. 2000).

The activity of the enzyme steroid sulfatase can be determined by a blood test, making this ichthyosis the only one to date that can be reliably detected by a simple blood sample.

Increase of cholesterol sulfate (approx. 10 times normal value) in blood cells and serum. Cholesterol in serum is decreased up to 50%.

Lipoprotein electrophoresis: Increased mobility of HDL and VLDL.

Retention hyperkeratosis with preserved, slightly widened stratum granulosum, distinct papillomatosis, 10-fold thickened interfollicular orthohyperkeratotic stratum corneum.

Electron microscopy: decreased number of keratinosomes.

• Adults: Initial 10-35 mg/day for 4 weeks, lowest possible maintenance dose after clinic (10-50 mg/day)
• In children, acitretin therapy only under strict consideration of benefit and risk: initial 0.5 mg/kg bw/day, maintenance dose: 0.1-0.2 mg/kg bw/day.

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