Striation of bones in focal dermal hypoplasia: manifestation of functional mosaicism?

Striation of the metaphyseal regions of the long bones, a characteristic feature of the focal dermal hypoplasia syndrome, may be explained by functional X chromosome mosaicism. The following arguments are in favour of this hypothesis: (I) The striation of bones coincides with the zones of osteogenesis. (2) The skin lesions are distributed in a linear pattern as well. (3) The syndrome is probably inherited as an X-linked dominant trait. Thus, the linear pattern of both skin and bone lesions could be due to random X inactivation.