Two mothers give birth to sons at the same time at a busy urban hospital. The son of mother 1 is afflicted with hemophilia, a disease caused by an X-linked recessive allele. Neither parent has the disease. Mother 2 has a normal son, despite the fact that the father has hemophilia. Several years later, couple 1 sues the hospital, claiming that these two newborns were swapped in the nursery following their birth. As a genetic counselor, you are called to testify. What information can you provide the jury concerning the allegation?

Hemophilia is a genetic disorder caused by a mutation in a gene on the X chromosome. It is an X-linked recessive disease, meaning that it predominantly affects males who have inherited one affected X chromosome from their carrier mother. Females can also be affected if they inherit the affected X chromosome from both their mother and their father, but this is very rare.

In order to determine if the newborns could have been swapped at birth, we first need to know the genotypes of the parents: Couple 1: Mother 1: Normal (likely carrier of hemophilia) => X^HX^h (X^H - normal X chromosome, X^h - X chromosome carrying hemophilia) Father 1: Normal => X^HY (Y chromosome, since he is a male) Couple 2: Mother 2: Normal => X^HX^H Father 2: Hemophilia => X^hY

Next, we will predict the possible genotypes of the offspring from each couple using a Punnett square. Offspring of Couple 1: The possible genotypes are X^HX^H (normal), X^HX^h (normal, carrier), X^HY (normal), and X^hY (hemophilia) Offspring of Couple 2: The possible genotypes are X^HX^h (normal, carrier), X^HY (normal), X^hX^h (hemophilia, female), and X^hY (hemophilia)

Now, let's analyze the results. Couple 1 claims that their son, who has hemophilia, was swapped with the son of couple 2, who does not have hemophilia. Considering that the son of couple 1 does have a genotype that could lead to hemophilia (X^hY), it is possible that they are indeed the biological parents. The son with hemophilia from couple 2 could also be their biological son, as that genotype is also plausible in offspring from couple 2 (X^hY). Similarly, the son without hemophilia being the biological child of couple 2 is also a possibility (X^HY). Based on this genetic analysis, it can be concluded that the claim of the newborns being swapped at birth is plausible but not definitive. Additional genetic testing would be needed to provide more compelling evidence and confirm the true parentage of these children.