Conflicts of interest None declared.
Analysis of the VCX3A, VCX2 and VCX3B genes shows that VCX3A gene deletion is not sufficient to result in mental retardation in X-linked ichthyosis
Article first published online: 12 DEC 2007
© 2007 The Authors
British Journal of Dermatology
Volume 158, Issue 3, pages 483–486, March 2008
How to Cite
Cuevas-Covarrubias, S.A. and González-Huerta, L.M. (2008), Analysis of the VCX3A, VCX2 and VCX3B genes shows that VCX3A gene deletion is not sufficient to result in mental retardation in X-linked ichthyosis. British Journal of Dermatology, 158: 483–486. doi: 10.1111/j.1365-2133.2007.08373.x
- Issue published online: 12 DEC 2007
- Article first published online: 12 DEC 2007
- Accepted for publication 25 April 2007
- mental retardation;
- steroid sulphatase;
- STS gene;
- VCX3A gene;
- X-linked ichthyosis
Background X-linked ichthyosis (XLI), an inborn error of metabolism, is due to steroid sulphatase (STS) deficiency. Most patients with XLI harbour complete deletion of the STS gene and flanking sequences. The presence of low copy number repeats on either side of the STS gene seems to have a major role in the high frequency of these deletions. Some patients with XLI with terminal deletions of Xp22.3 involving marker DXS1139 and the STS gene show mental retardation (MR); VCX3A is the only gene located on this critical region.
Objectives To analyse the VCX3A, VCX, VCX2 and VCX3B genes in 80 unrelated Mexican patients with XLI with normal intelligence.
Methods STS activity was measured in the leucocytes using 7-[3H]-dehydroepiandrosterone sulphate as a substrate. Amplification of the regions from telomeric DXS89 to centromeric DXS1134 including both extremes of the STS and the VCX3A, VCX, VCX2 and VCX3B genes was performed using polymerase chain reaction.
Results No STS activity was detected in the patients with XLI (0·00 pmol mg−1 protein h−1). We observed two different deletion patterns: the first group included 62 patients with deletion of VCX3A and VCX genes. The second group included 18 patients with breakpoints at several regions on either side of the STS gene not including the VCX3A gene.
Conclusions These data indicate that more complex mechanisms, apart from possible VCX3A gene participation, are occurring in the genesis of MR in XLI, at least in the sample of Mexican patients analysed.