▁modified ▁by ▁cogn itive ▁imp air ment : ▁it ▁may ▁be ▁close ▁to ▁ 2 : 1 ▁with ▁mental ▁ret ard ation ▁and ▁more ▁than ▁ 5 . 5 : 1 ▁without . ▁Rec ent ▁studies ▁have ▁found ▁no ▁association ▁with ▁so cio e conom ic ▁status , ▁and ▁have ▁reported ▁incons istent ▁results ▁about ▁associations ▁with ▁race ▁or ▁eth nic ity . ▁ ▁R OR A ▁def ic iency ▁may ▁explain ▁some ▁of ▁the ▁difference ▁in ▁frequency ▁between ▁males ▁and ▁females . ▁R OR A ▁protein ▁levels ▁are ▁higher ▁in ▁the ▁bra ins ▁of ▁typically ▁developing ▁females ▁compared ▁to ▁typically ▁developing ▁males , ▁providing ▁females ▁with ▁a ▁buffer ▁against ▁R OR A ▁def ic iency . ▁This ▁is ▁known ▁as ▁the ▁Fem ale ▁protect ive ▁effect . ▁R OR A ▁def ic iency ▁has ▁previously ▁been ▁proposed ▁as ▁one ▁factor ▁that ▁may ▁make ▁males ▁more ▁vulner able ▁to ▁aut ism . ▁ ▁Com orb id ▁conditions ▁ ▁Aut ism ▁is ▁associated ▁with ▁several ▁other ▁conditions : ▁Gen etic ▁dis orders . ▁About ▁ 1 0 – 1 5 % ▁of ▁aut ism ▁cases ▁have ▁an ▁ident ifiable ▁M end elian ▁( single - g ene ) ▁condition , ▁chrom os ome ▁ab normal ity , ▁or ▁other ▁gen etic ▁synd rome , ▁and ▁AS D ▁is ▁associated ▁with ▁several ▁gen etic ▁dis orders . ▁Intel lect ual ▁dis ability . ▁The ▁fraction ▁of ▁aut istic ▁individuals ▁who ▁also ▁meet ▁criteria ▁for ▁intellectual ▁dis ability ▁has ▁been ▁reported ▁as ▁anywhere ▁from ▁ 2