Lonakan, osu kan si meta gbodo waye laarin oogun lilo akoko ti osu maarun si mejila yoo tele ki o to lo oogun ti o kehin.. 
Protein tí ó ń kóòddù fún SPG21 gene ní ìrẹ́pọ̀ pẹ̀lú ALDH16A1 enzyme enzyme.Àwọn ìtọ́kasí àyọkà àkurú.. 