The pedigree shows history from both the Maretta and Dupree families.
This pedigree shows that this case of Severe Combined Immunodeficiency Syndrome is a sex-linked recessive trait. This is present because only women are heterozygous and carriers. Sex-linked traits are traits that are only present on the x chromosome. Men have one x chromosome while women have two. That's why, when the sex-linked trait is recessive, the trait is more common in men, and women are usually carriers. The pedigree shows that the mother, Terese Dupree, is a carrier. This means that she has one x chromosome that is affected with the gene while she has another x chromosome that is normal. Therefore, she does not show the gene, but she can pass it on to her children. Because the baby is a boy, there is a higher possibility for the baby to receive SCID, and he has a fifty percent chance of receiving either a normal x chromosome or an x chromosome that is affected with the sex-linked trait from the mother. It is recommended that Terese Dupree goes through a newborn screening test to see whether or not the child will have SCID with the family history. With early diagnosis, treatments can be done earlier to help the child live a healthy normal life.
Lawrence and Terese Dupree's Punnett Square for Their Baby Boy
The Dupree's punnett square shows the possibility that there baby boy will be affected with SCID. Males have one x and one y chromosome; therefore, the two boxes in the bottom row of the punnett square shows the possibility that the offspring will be affected. The genotypic ratios for the couple is as follows: xBy- 50%, xby-50%. This means that there is a 50% chance that the baby will receive the normal x chromosome from mom, and there is a 50% chance that the baby will receive an x-chromosome that is affected with the sex-linked gene of severe combined immunodeficiency syndrome. However, these are just possibilities, but if the Dupree family want to know for certain whether or not their child will be diagnosed, they should get a prenatal testing.