▁th ir teen ▁anonymous ▁volunte ers . ▁ ▁As ▁the ▁cost ▁of ▁DNA ▁sequ encing ▁falls , ▁and ▁new ▁full ▁gen ome ▁sequ encing ▁techn ologies ▁emer ge , ▁more ▁gen ome ▁sequences ▁continue ▁to ▁be ▁generated . ▁Reference ▁genom es ▁are ▁typically ▁used ▁as ▁a ▁guide ▁on ▁which ▁new ▁genom es ▁are ▁built , ▁en abling ▁them ▁to ▁be ▁assemble d ▁much ▁more ▁quickly ▁and ▁cheap ly ▁than ▁the ▁initial ▁Human ▁Gen ome ▁Project . ▁Most ▁individuals ▁with ▁their ▁entire ▁gen ome ▁sequ enced , ▁such ▁as ▁James ▁D . ▁Watson , ▁had ▁their ▁gen ome ▁ ▁assemble d ▁in ▁this ▁manner . ▁For ▁much ▁of ▁a ▁gen ome , ▁the ▁reference ▁provides ▁a ▁good ▁approximation ▁of ▁the ▁DNA ▁of ▁any ▁single ▁individual . ▁But ▁in ▁regions ▁with ▁high ▁alle lic ▁divers ity , ▁such ▁as ▁the ▁major ▁h isto compat ibility ▁complex ▁in ▁humans ▁and ▁the ▁major ▁ur inary ▁prote ins ▁of ▁m ice , ▁the ▁reference ▁gen ome ▁may ▁differ ▁significantly ▁from ▁other ▁individuals . ▁Com parison ▁between ▁the ▁reference ▁( build ▁ 3 6 ) ▁and ▁Watson ' s ▁gen ome ▁revealed ▁ 3 . 3   mill ion ▁single ▁nucle ot ide ▁polym orphism ▁differences , ▁while ▁about ▁ 1 . 4 ▁percent ▁of ▁ ▁his ▁DNA ▁could ▁not ▁be ▁matched ▁to ▁the ▁reference ▁gen ome ▁at ▁all . ▁For ▁regions ▁where ▁there ▁is ▁known ▁to ▁be ▁large ▁scale ▁variation , ▁sets ▁of ▁alternate ▁lo ci ▁are ▁assemble d ▁alongside ▁the ▁reference ▁loc us . ▁ ▁Reference ▁genom