X-linked recessive ichthyosis

Recessive X-linked ichthyosis (RXLI) steroid sulfatase deficiency STS Xp22.32 308100... 

Recessive X-linked ichthyosis (RXLI) is a dermatological condition that is caused by steroid sulfatase deficiency (STSD), although the mechanism by which the deficiency causes the characteristic scaly skin has not been adequately explained. RXLI is the most common genetic disorder of steroid metabolism, affecting about 1 2000 males. Epstein and workers [16] first demonstrated that serum cholesterol sulfate was elevated in the condition, and this compound has become the preferred analyte for diagnosis. The serum level is more than tenfold greater than normal in the condition. 

Shackleton CH, Reid S (1989) Diagnosis of recessive X-linked ichthyosis quantitative HPLC/ mass spectrometric analysis of plasma for cholesterol sulfate. Clin Chem 35 1906-1910... 

In recessive X-linked ichthyosis, the amount of cholesterol sulfate in the stratum corneum is increased due to a deficiency in cholesterol sulfatase deficiency [69,70], Lipid analysis of scales reveals a nearly 10-fold increase in the cholesterol sulfate to free cholesterol ratio as compared to healthy stratum corneum [71]. Previous x-ray diffraction studies on isolated ceramide mixtures revealed that increased cholesterol sulfate levels induce the formation of a fluid phase, which is likely to reduce the skin barrier function [72]. 

Cholesterol sulfate is another intercellular lipid. Addition of low levels of cholesterol sulfate, as observed in normal healthy stratum corneum, to lipid mixtures has little effect on the phase behavior at room temperature. However, addition of high levels of cholesterol sulfate, at levels similar to that observed in the skin disease recessive X-linked ichthyosis, promotes the formation of the long periodicity phase, induces the formation of a fluid phase, and increases the solubility of cholesterol in the lamellar phases [72,80],... 

Zettersten, E., et al. Recessive x-linked ichthyosis Role of cholesterol-sulfate accumulation in the barrier abnormality. J Invest Dermatol 111 784. 

Rehfeld, S.J., et al. 1988. Calorimetric and electron spin resonance examination of lipid phase transitions in human stratum corneum Molecular basis for normal cohesion and abnormal desquamation in recessive X-linked ichthyosis. J Invest Dermatol 91 499. 

Williams, M.L., and P.M. Elias. 1981. Stratum corneum lipids in disorders of cornification Increased cholesterol sulfate content of stratum corneum in recessive x-linked ichthyosis. J Clin Invest 68 1404. 

An accumulation of scales on the skin surface may be due to either an increased production of corneocytes, such as in psoriasis, or to a delayed desquamation. It may be predicted that conditions with delayed desquamation, once their pathophysiology on the molecular level is understood, will be highly informative with regard to the understanding of desquamation. Two such conditions are recessive X-linked ichthyosis (RXI) and lamellar ichthyosis. 

Ibsen, H., Brandrup, F., Blaabjerg, I., and Lykkesfeldt, G., Lipoprotein electrophoresis in recessive x-linked ichthyosis, Acfa Derm. Venereol., 66, 59, 1986. 

Zettersten, E., Man, M.-Q., Sato, J., Denda, M., Farrell, A., Ghadially, R., Williams, M., Feingold, K., and Elias, R, Recessive x-linked ichthyosis role of cholesterol sulfate accumualtion in the barrier abnormality, J. Invest. Dermatol., Ill, 784, 1998. 

Lykkesfeldt, G. and Hoyer, H., Topical cholesterol treatment of recessive x-linked ichthyosis, Lancet, 2, 1337, 1983. 

The most common forms of ichthyosis — autosomal dominant ichthyosis vulgaris (IV) and X-linked recessive ichthyosis (XRI) — in many countries occur at frequencies a high as 1/300 and 1/2500, respectively. In fact, the genetic traits for IV and XRI are so frequent that the two diseases sometimes coexist in one and the same family, which may cause confusion as to the inheritance pattern. Although the incidence of IV and XRI is probably similar around the world, climate differences in particular will affect the severity of the disease, and hence its notification by the health care system. 

Clinical and Biological Features Distinguishing Ichthyosis vulgaris (IV) from X-linked Recessive Ichthyosis (XRI)... 

FIGURE 8.3 Schematic representation of the pH gradients over stratum corneum in normal skin, Ichthyosis vulgaris (IV), and X-linked Recessive Ichthyosis (XRI) skin, respectively. (Reproduced from Ohman, H. and Vahlquist, A., J. Invest. Dermatol., Ill, 674, 1998. With permission.)... 

Figure 10.3 Comparison of keratohyalin (KH) amount and ultrastructure in autosomal dominant ichthyosis vulgaris (a) and X-linked recessive ichthyosis (b) x31 500...

In most recessive types merely quantitative deviations from the normal keratinization process have been found (X-linked recessive ichthyosis, lamellar... 

Anton-Lamprecht, I. and Hofbauer, M. (1972). Ultrastructural distinction of autosomal dominant ichthyosis vulgaris and X-linked recessive ichthyosis. Humangenetik, 15,261... 

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