Lactose Intolerance 

The pedigree above of American Indian families ilustrates the lost and persistence of lactase. As we can see in the  pedigree, it is shown that since the first generation both grandpas and sons are lactose intolerant proving that these disease is present in many descendents of the American Indian Family.  

 

Lactose Intolerance is inherited as an autosomal recessive trait. Looking at the pedigree we can say that in the first pedigree, the parents genotype is lct: homozygous recessive and their offspring code for lct: homozygous reccesive. In the second pedigree sample we can see that in the first generation the mother is affected meaning that her gebotype is lct: homozygous recessive and the parent is lactose tolerant meaning that his genotype is LCT: homozigous dominant and 4 of their offspring are affected meaning that their genotype is recessive, three are unknown and 2 are lactose tolerant. Finally the third pedigree is more diverse cause both parents are lactose tolerant but the grand  is a carrier cause two of their offspring are lactose intolerant, two are lactose tolerant, one is unknown and other its sex is unknown;  the third generation eight are lactose intolerant so their genotype is recessive, six are lactose tolerant meaning that their genotype is dominant and the other its sex is unknown so the information is unavalable