Mutations in the genes for clotting factor VIII and IX cause hemophilia A and B, respectively. A woman may be heterozygous for mutations in both genes, with a mutated factor VIII allele on one X chromosome, and a mutated factor IX allele on the other. All of her sons should have either hemophilia A or B. However, on rare occasions, one of these women gives birth to a son who does not have hemophilia, and his one X chromosome does not have either mutated allele.

Predict the probability (using a Punnett square) of producing an offspring affected by a single gene X-linked mutation given the genotype of the parents. Compare these crosses in two cases: where the mutant allele is “A” vs where the mutant allele is “a” (XAXA x XaY) (XAXa x XAY) (XAXa x XaY) (XaXa x XAY) (XaXa x XaY). Include gender in the phenotype.

Hemophilia, disease in which the blood lacks a clotting factor, is caused by an X linked recessive gene. Joe doe not have hemophilia and Lucille is heterozygous for the condition.  What is the chance that their MALE child will have hemophilia? (Note: you are calculating the probability for their MALE children only, in other words if they have 1 male child, what is the probability that he will be born with the disease?)     0%     1/4 or 25%     2/4 or 50%     3/4 or 75%     4/4 or 100%

Sickle cell anemia is an inheritable red blood cell disorder that results in sickle-shaped red blood cells. The sickle-shaped red blood cells can stick to blood vessel walls and cause a blockage or slow the movement of blood throughout the body.   Individuals who are heterozygous produce both normal and sickle-shaped red blood cells which gives them resistance to malaria but they do not develop sickle cell anemia (so heterozygotes are unaffected on the pedigree).Let HbS be the allele for sickle cell anemia and let HbA be the allele for normal red blood cells. Which of the following rows provides the correct genotypes for individuals I-2, I-4, II-1, and III-1? Select one: a. I-2 I-4 II-1 III-1 HbA_ HbAHbS HbAHbS HbA_ b. I-2 I-4 II-1 III-1 HbA_  HbAHbS HbAHbS HbAHbS c. I-2 I-4 II-1 III-1 HbAHbS HbAHbS HbAHbS HbAHbS d. I-2 I-4 II-1 III-1 HbAHbA HbAHbA HbAHbA HbAHbA

Several genes in humans in addition to the ABO gene () give rise to recognizable antigens on the surface of the red blood cells. The Rh marker is determined by positive (R) and negative alleles () of gene R, where R is completely dominant to r. The presence of M and N surface proteins are controlled by two codominant alleles of gene L (LM and LM. For each mother-child pair, choose the father of the child from among the males in the right column. (Assume that all mothers and fathers are HH; there is no involvement of the Bombay phenotype.) Paternal genotypes maybe used once, more than once, or not at all. Each mother-child pair matches with one or more than one paternal genotype. Maternal phenotype: Child phenotype: Paternal genotype: Reset A, M, Rh(neg) O, M, Rh(pos) B, N, Rh(neg) O, N, Rh(pos) O, M, Rh(neg) A, MN, Rh(pos) A, N, Rh(pos) AB, MN, Rh(pos) B, N, Rh(pos) A, MN, Rh(neg) Genotypes of possible fathers AiLMLN rr BiLMLN RR ii LNLN rr ii LMLM rr AALMLN RR

Give the typical sex-chromosome complement found in the cells of people with Turner syndrome, with Klinefelter syndrome, and with androgen-insensitivity syndrome. What is the sex-chromosome complement of triple-X females?

In blood groups, Rh positive blood is dominant (R) over the gene for Rh negative blood (r). What types of offspring could be expected for an Rh positive AB woman, (whose father was Rh negative), who marries a man with heterozygous A positive blood?

How can the retinoblastoma trait be inherited in a dominant fashion if the deletion of the RB gene is recessive to the wild-type RB+ allele?

How many males have hemopilia? (refer to image).