While the majority of HSP patients belongs to the SPG4 group and SPG3 incidence rates are occupying the 2nd place in our DNA screening (as SPG4 cases were collected for a longer period), which is corresponding to the world data, the proportion of AD SPG30 has unexpectedly appeared as the 3rd most common SPG form in Russian cohort (8.4%; for the subgroup of AD forms 10.3%). The gene discussed is SPAST; the disease is Alzheimer disease.