Abstract
We studied the expression of the X-linked steroid sulphatase (STS) gene in single hair roots of patients with X-linked ichthyosis, obligate heterozygotes and controls. STS activity was expressed as the amount of radiolabeled dihydro-epiandrosterone (DHEA) literated from DEAH-S per hair root in 5 hours. Nine patients with X-linied ichthyosis had an STS activity < 0.3 pmole DHEA per hair root in 5 hours. This is far below the activity of 12 male controls (4.6±1.8 pmole DHEA per hair root in 5 hours) and allows the reliable detection of the patient by means of the assay of single hair roots. Each hair root of 7 obligate heterozygotes had an STS activity in the control range (3.0±0.9) and the frequency distribution of the STS activities did not show a bimodal distribution, which would have been compatible with X-inactivation. The STS activity of 12 control females (6.0±1.8), on the other hand, was significantly higher than that of the control males (4.6±1.8) and the heterozygotes (3.0±0.9). The STS activity ratio between control females and males, calculated from these mean values (1.3) is compatible with partial gene dosage compensation of the STS locus. Both the absence of a subpopulation of hair follicles with deficient STS activity in obligate heterozygotes and the gene dosage effect suggest incomplete X-inactivation of the steroid sulphatase gene.
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Willems, P., De Bruijn, H., Groenhuis, A. et al. Expression of the X-linked steroid sulphatase gene in single hair roots. Pediatr Res 18, 803 (1984). https://doi.org/10.1203/00006450-198408000-00071
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DOI: https://doi.org/10.1203/00006450-198408000-00071