8. This family pedigree follows a family afflicted by a trait determined by the R gene IdA 2 9 10 11 12 13 14 15 16 17 18 19 e. What is the genotype of individual 1: f. What is the genotype of individual 6: g. What is the genotype of individual 2: h. What is the genotype of individual 13: i. Is this trait autosomal dominant, recessive, or X-linked recessive? Why? |

8. This family pedigree follows a family afflicted by a trait determined by the R gene IdA 2 9 10 11 12 13 14 15 16 17 18 19 e. What is the genotype of individual 1: f. What is the genotype of individual 6: g. What is the genotype of individual 2: h. What is the genotype of individual 13: i. Is this trait autosomal dominant, recessive, or X-linked recessive? Why? |

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter10: From Proteins To Phenotypes

Section: Chapter Questions

Problem 3CS: A couple was referred for genetic counseling because they wanted to know the chances of having a...

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A couple was referred for genetic counseling because they wanted to know the chances of having a child with dwarfism. Both the man and the woman had achondroplasia (MIM 100800), the most common form of short-limbed dwarfism. The couple knew that this condition is inherited as an autosomal dominant trait, but they were unsure what kind of physical manifestations a child would have if it inherited both mutant alleles. They were each heterozygous for the FGFR3 (MIM 134934) allele that causes achondroplasia. Normally, the protein encoded by this gene interacts with growth factors outside the cell and receives signals that control growth and development. In achrodroplasia, a mutation alters the activity of the receptor, resulting in a characteristic form of dwarfism. Because both the normal and mutant forms of the FGFR3 protein act before birth, no treatment for achrondroplasia is available. The parents each carry one normal allele and one mutant allele of FGRF3, and they wanted information on their chances of having a homozygous child. The counsellor briefly reviewed the phenotypic features of individuals with achondroplasia. These include facial features (large head with prominent forehead; small, flat nasal bridge; and prominent jaw), very short stature, and shortening of the arms and legs. Physical examination and skeletal X-ray films are used to diagnose this condition. Final adult height is approximately 4 feet. Because achondroplasia is an autosomal dominant condition, a heterozygote has a 1-in-2, or 50%, chance of passing this trait to his or her offspring. However, about 75% of those with achondroplasia have parents of average size who do not carry the mutant allele. In these cases, achondroplasia is due to a new mutation. In the couple being counseled, each individual is heterozygous, and they are at risk for having a homozygous child with two copies of the mutated gene. Infants with homozygous achondroplasia are either stillborn or die shortly after birth. The counselor recommended prenatal diagnosis via ultrasounds at various stages of development. In addition, a DNA test is available to detect the homozygous condition prenatally. What is the chance that this couple will have a child with two copies of the dominant mutant gene? What is the chance that the child will have normal height?
A couple was referred for genetic counseling because they wanted to know the chances of having a child with dwarfism. Both the man and the woman had achondroplasia (MIM 100800), the most common form of short-limbed dwarfism. The couple knew that this condition is inherited as an autosomal dominant trait, but they were unsure what kind of physical manifestations a child would have if it inherited both mutant alleles. They were each heterozygous for the FGFR3 (MIM 134934) allele that causes achondroplasia. Normally, the protein encoded by this gene interacts with growth factors outside the cell and receives signals that control growth and development. In achrodroplasia, a mutation alters the activity of the receptor, resulting in a characteristic form of dwarfism. Because both the normal and mutant forms of the FGFR3 protein act before birth, no treatment for achrondroplasia is available. The parents each carry one normal allele and one mutant allele of FGRF3, and they wanted information on their chances of having a homozygous child. The counsellor briefly reviewed the phenotypic features of individuals with achondroplasia. These include facial features (large head with prominent forehead; small, flat nasal bridge; and prominent jaw), very short stature, and shortening of the arms and legs. Physical examination and skeletal X-ray films are used to diagnose this condition. Final adult height is approximately 4 feet. Because achondroplasia is an autosomal dominant condition, a heterozygote has a 1-in-2, or 50%, chance of passing this trait to his or her offspring. However, about 75% of those with achondroplasia have parents of average size who do not carry the mutant allele. In these cases, achondroplasia is due to a new mutation. In the couple being counseled, each individual is heterozygous, and they are at risk for having a homozygous child with two copies of the mutated gene. Infants with homozygous achondroplasia are either stillborn or die shortly after birth. The counselor recommended prenatal diagnosis via ultrasounds at various stages of development. In addition, a DNA test is available to detect the homozygous condition prenatally. Should the parents be concerned about the heterozygous condition as well as the homozygous mutant condition?
6. Identify the mode of inheritance for the following pedigree. Provide the genotypes of indicated individuals. ? Genotypes: Il-1 IV-1 V-6 Il-2 IV-2 V-12 Il-3 IV-3 V- 14 III-1 IV-4 V-16 III-13 V- 1 V-19
6. The pedigree below traces the inheritance of a particular disorder. Circles are females, squares are males. Shaded symbols are affected with the disorder (NOTE: "half-shaded" symbols are NOT used here, for heterozygous individuals). What is the mode of inheritance of this disorder: is it dominant or recessive? Autosomal or X-linked? What is the genotype of the three numbered individuals? 1 2. 3.
11. Below is a pedigree chart of an autosomal recessive disorder. Answer the following questions using the correct genetic terminology (do not just write letters like “Ee”). A. What is the genotype of individual 1 in generation II? B: What is the genotype of individual 2 in generation I?C: Is it true that individuals 6, 7, 8, 9, and 10 in generation III all have the same genotype? Why or why not?
re ||| E 6. Label the genotypes for this pedigree of an X-linked recessive disorder (red- green colorblindness). (a) 2 2 3 1 3 a. How do you know? b. Label the genotypes. 4 O To 2 4 5 5 6 6 7. Is the following pedigree autosomal recessive, autosomal dominant or X-linked recessive? 2 8 O T 58
10. Examine the pedigree from a family with a genetic disease and answer the questions below: 1:1 1:2 I1:1 II:2 I1:3 Il:4 II:5 I1:6 II:1 III:2 II:3 I:4 III:5 II:6 a) Does this pedigree indicate autosomal dominant, recessive or sex- linked type of inheritance? Give reasons for your choice. b) Assuming that B and b are the normal and mutant alleles respectively, what would be the genotypes of the individuals: II.1, II.2 and III.3 ? c) Individual II.3 requested genetic counselling. What is the probability that her child would be affected. Explain why.
II. Given the following pedigree below, use Punnett squares for each of the following possibilities: a) X- linked dominant and b) X-linked recessive in order to determine what is the mode of transmission of this trait. Disease allele = XA or Xª, depending on mode of transmission of the disease respectively. *Unaffected/No carrier-Normal Unaffected X chromosome = X I || III 1 1 2 a) X-linked recessive 9 III 6 genotype (circle one): XX * 1 2 3 11x12 4 ΧΑΧΑ 2 5 xaxa *4 6 7 8 b) X-linked dominant 11 x 12 오 XAX хах
9. Explain, giving reasons, whether the following pedigrees are compatible with autosomal dominant, autosomal recessive or X-linked dominant and X-linked recessive inheritance. (Note that a pedigree may be compatible with more than one type of inheritance.) 1:1 12 1:1 12 1:1 1:2 I12 I:4 IIS II:1 I12 II:1 I1:2 Il:3 I1:4 II2 II:1 III3 II:1 II:2 III:3 III:4 a. b. c.
1 pts The pedigree below shows the expression of Huntington's disease in a family. Huntington's disease is a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain. It deteriorates a person's physical and mental abilities usually during their prime working years and has no cure. Huntington's is inherited as a dominant allele (H). Examine the pedigree below and determine the genotype for individual "2" DODO0O 2. O HH O Hh О h O either HH or Hh
5. The pedigree below traces the inheritance of Albinism, a genetic disorder. Affected individuals, indicated here by the coloured circles and squares, are unable to make a normal amount of melanin, the chemical that is responsible for eye, skin, and hair colour. Does Albinism appear to be caused by a dominant allele or by a recessive allele? Fill in the genotypes of the individuals whose genotypes can be deduced. What genotypes are possible for each of the other individuals? Explain! Naruto Hinata Reiner Asta Hange Mikasa Eren Historia Luffy Nezuko Zenitsu Tanjiro Son Goku
1. In the pedigree below, Use "A" for the allele associated with the dominant phenotype, and lowercase "a" for the allele associated with the recessive phenotype. Determine what is the most likely mode of inheritance of this disease (whether it is inherited as the result of an autosomal dominant or autosomal recessive trait). Write the most probable genotype for each individual based on the mode of inheritance you have determined. Show how all the partners are crossed and the expected offspring produced (You may use Punnett Square) 1 dró || IV