Reduced penetrance in a family with X-linked dominant chondrodysplasia punctata.

X-linked dominant chondrodysplasia punctata (Conradi-Hünermann disease, CDPX2) is characterised by short stature, stippled epiphyses, cataracts, ichthyosiform erythroderma and patchy alopecia of the scalp. The disorder is caused by mutations within the emopamil binding protein (EBP) gene encoding a 3beta-hydroxysteroid-Delta(8),Delta(7)-isomerase. The intrafamilial variation of disease severity is a known feature of CDPX2 probably caused by skewed X-inactivation.