However, as DDHD1 expression was found to be suppressed in embryos and expressed on postnatal day 8 (data not shown), the time when striking development of the brain’s fiber tracts as well as remodeling of cortical and subcortical structure occurs, DDHD1 may have some functions in brain development, especially in humans in which its mutation causes HSP (Tesson et al., 2012). The gene discussed is DDHD1; the disease is hereditary spastic paraplegia.