Coexistence of two types of clinical lesions in childhood-onset mastocytosis.

The vast majority of mastocytosis appear in childhood, urticaria pigmentosa (UP) and mastocytomas being the most common types. Terms such as "xanthelasmoid mastocytosis", "pseudoxanthomatous mastocytosis" or "nodular mastocytosis" have been introduced in the literature to describe the presence of yellowish papular or nodular lesions. We describe two children with cutaneous mastocytosis showing yellowish lesions in combination with other skin lesions.

Phylogenetics of worldwide human populations as determined by polymorphic Alu insertions.

Alu elements, the largest family of interspersed repeats, mobilize throughout the genomes of primates by retroposition. Alu are present in humans in an excess of 500 000 copies per haploid genome. Since some of the insertion alleles have not reached fixation, they remain polymorphic and can be used as biallelic DNA marker systems in investigations of human evolution.