Suggest Remedy For Itchy And Red Spots On The Skin

Hi I have a genetic problem which my mom n grandma having the samething. V r having spots on our whole body . Spots that expose to sun are dark n remaining are white .They are very deep into the skin. I didnt get this by birth .At the age of 12 they started n going on increase upto certain age.They r very itchy n become red when expose to sun without any sunscreen.Is there any solution for this ?