MPL and thrombocytopenia-absent radius syndrome: Due to the developmental changes in Mpl expression in the SVZ of the telencephalon and in the cerebellum (downregulation in the white matter; upregulation in Purkinje cells) as well as structural and functional abnormalities in the brain of some patients with impaired Mpl function (CAMT, TAR syndrome) affecting particularly the cerebellum [16,19-21], we expected structural abnormalities in the brain of mutant mice with homozygous Mpl deficiency.