In humans, hemophilia is an X-linked recessive gene and will only be expressed in females if they are homozygous for this gene. However, in some rare cases, a heterozygote becomes hemophilic. Explain thoroughly how this happened.

In humans, hemophilia is an X-linked recessive gene and will only be expressed in females if they are homozygous for this gene. However, in some rare cases, a heterozygote becomes hemophilic. Explain thoroughly how this happened.

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Description: In humans, hemophilia is an X-linked recessive gene and will only be expressed in females if they are homozygous for this gene. However, in some rare cases, a heterozygote becomes hemophilic.Explain thoroughly how this happened.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter11: Genome Alterations: Mutation And Epigenetics

Section: Chapter Questions

Problem 16QP: Familial retinoblastoma, a rare autosomal dominant defect, arose in a large family that had no prior...

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Human females who are heterozygous for an X-linked recessive allele sometimes exhibit mild expression of the trait. However, such mild expression of X-linked traits in females who are heterozygous for Xlinked alleles is not seen in Drosophila. What might cause this difference in the expression of X-linked genes between human females and female Drosophila? (Hint: In Drosophila, dosage compensation is accomplished by doubling the activity of genes on the X chromosome of males.)
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. Explain.
Colorblindness and hemophilia are both X-linked traits in humans. Explain how a female who has a defective color vision gene on one X chromosome and a defective blood clotting gene causing hemophilia on the other X chromosome can be neither a hemophiliac nor colorblind? Please discuss the effect of Gene dosage compensation in your answer and in your answer describe the molecular process by which this occurs.
The gene causing Coffin-Lowry syndrome (OMIM 303600) was recently identified and mapped on the human X chromosome. Coffin-Lowry syndrome is a rare disorder affecting brain morphology and development. It also produces skeletal and growth abnormalities, as well as abnormalities of motor control. Coffin-Lowry syndrome affects males who inherit a mutation of the X-linked gene. Most carrier females show no symptoms of the disease but a few carriers do. These carrier females are always less severely affected than males. Offer an explanation for this finding.
Lauren reports that she had a maternal male cousin (through a maternal aunt) and a maternal great uncle (maternal grandmother’s brother) both pass away from the same x-linked lethal condition. Both affected individuals did not have genetic testing. Lauren has a normal carrier screen for x-linked lethal conditions, which you know identifies 40% of causative mutations. If Lauren is currently pregnant with a male child, what is the chance that this child will have the condition?
One of the most famous cases of an X-linked recessive mutation in humans is that of hemophilia found in the descendants of Britain’s Queen Victoria. The pedigree of the royal family indicates that Victoria was heterozygous for the trait; however, her father was not affected, and no other member of her maternal line appeared to carry the mutation. What are some possible explanations of how the mutation arose? What types of mutations could lead to the disease?
In humans, hemophilia is an X-linked recessive disorder that affects the gene for factor VIII protein, which is essential for blood clotting. The dominant and recessive alleles for the factor VIII gene are represented by H and h. Albinism is an autosomal recessive condition involving the tyrosinase enzyme which synthesizes pigment. Alleles of tyrosinase are represented by A and a. The provided pedigree shows a new marriage between Clara and Charles. A) Review the pedigree, filling in any genotypes that can be determined from the displayed traits. B) What is the probability that their first child will display hemophilia, albinism, or BOTH hemophilia AND albinism.C) If Clara and Charles first child has albinism, what is the probability that the second child will also display albinism?
. In humans, hemophilia is an X-linked recessive gene and will only be expressed in females if they are homozygous for this gene. However, in some rare cases, a heterozygote becomes hemophilic. Explain how this incident happens and why will there be skewed X-inactivation?
Males of many diploid species (like us) have X and Y sex chromosomes. They are hemizygous for most X- linked genes. Thus, males express most X-linked alleles, whether they are dominant or recessive in females. In the fruit fly Drosophila, it is common to achieve the equivalent of a test cross of X-linked genes in females by assessing the readily observed phenotypes of their male progeny. Since males do not receive X-linked genes from their father, sires of these crosses can be normal or wild-type flies. In fly genetics, it is conventional to name a gene after the mutant phenotype that enabled its discovery. Your challenge is to establish gene order and map distances between three X-linked genes in Drosophila. Each gene is represented by recessive mutant alleles that express rather distinctive phenotypes relative to their dominant wild-type alternative alleles. Flies expressing fruitless (f) are bisexual, lush (1) have a heightened responses to ethanol, and ken&barbie (kb) lack external…
Anhidrotic ectodermal dysplasia is an X-linked recessive disorder in humans characterized by small teeth, no sweat glands, and sparse body hair. This trait is usually seen in men, but women who are heterozygous carriers of the trait often have irregular patches of skin with few or no sweat glands (see the illustration below). a. Explain why women who are heterozygous carriers of a recessive gene for anhidrotic ectodermal dysplasia have irregular patches of skin lacking sweat glands. b. Why does the distribution of the patches of skin lacking sweat glands differ among the females depicted in the illustration, even between the identical twins?
Familial retinoblastoma, a rare autosomal dominant defect, arose in a large family that had no prior history of the disease. Consider the following pedigree (the darkly colored symbols represent affected individuals): a. Circle the individual(s) in which the mutation most likely occurred. b. Is the person who is the source of the mutation affected by retinoblastoma? Justify your answer. c. Assuming that the mutant allele is fully penetrant, what is the chance that an affected individual will have an affected child?
Duchenne Muscular Dystrophy (DMD) is a disorder that primarily affects the function of skeletal muscles used for movement and cardiac muscles used for heart beating. Dystrophin is a protein encoded by a single gene, DMD, that is expressed in skeletal and cardiac muscle. Some forms of muscular dystrophy may be caused by different mutations in the DNA sequence of the DMD gene. Because the DMD locus is on the X chromosome, males are affected at higher rates. Two brothers, one of whom has DMD and one of whom does not, worked with their genetic counselor (Links to an external site.) to have their DMD gene sequenced to identify genetic variation that may explain why one brother was affected and the other not. Because DMD is a very long gene, a fictionalized, simplified model of the results is presented here (Figure 1). The actual DMD mRNA is about 16,000 base-pairs!------Consider single nucleotide polymorphism (SNP) #1 (Figure 1). Is this mutation likely to cause Duchenne muscular…