Melorheostosis may originate as a type 2 segmental manifestation of osteopoikilosis

Melorheostosis is a non-hereditary disorder involving the bones in a segmental pattern, whereas osteopoikilosis is a rather mild disseminated bone disorder inherited as an autosomal dominant trait. Interestingly, melorheostosis and osteopoikilosis may sometimes occur together. In analogy to various autosomal dominant skin disorders for which a type 2 segmental manifestation has been postulated, melorheostosis may be best explained in such cases as a type 2 segmental osteopoikilosis, resulting from early loss of the corresponding wild type allele at the gene locus of this autosomal dominant bone disorder.