The following pedigree shows inheritance of Huntington's disease, a fatal genetic disorder that causes neurodegeneration. Since signs and symptoms usually do not appear until adulthood, many who are carriers may not realize their risk of passing a the disease-causing allele. The following pedigree represents a family in which some people are affected by Huntington's disease. Reeesslve Trait pically రాంి m Domin

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**Pedigree and Inheritance of Huntington's Disease**

The following pedigree illustrates the inheritance pattern of Huntington's disease, a fatal genetic disorder characterized by neurodegeneration. As the signs and symptoms often do not manifest until adulthood, carriers may unknowingly pass on the disease-causing allele. The pedigree below reflects a family with members affected by Huntington's disease.

**Key Features of the Pedigrees:**

(a) *Autosomal Recessive Trait*
- The diagram displays a typical autosomal recessive inheritance pattern, where individuals must inherit two copies of the recessive allele to express the trait.
- Important notes in the diagram:
  - Either I-2 or I-4 must be heterozygous.
  - Recessive traits often skip generations.
  - Recessive patterns generally show up only when both parents carry the recessive allele.

(b) *Autosomal Dominant Trait*
- This portion shows an autosomal dominant trait, where only one copy of the allele is needed to express the disorder.
- Important notes in the diagram:
  - I-1 is heterozygous for the dominant allele.
  - Dominant traits seldom skip generations, with affected individuals appearing in each generation.
  - Every affected individual possesses at least one affected parent.
  - Affected individuals will all have the dominant allele.
  - The dominant allele displays readily in both sexes across generations.

These diagrams illustrate genetic inheritance patterns crucial for understanding Huntington’s disease in families.
Transcribed Image Text:**Pedigree and Inheritance of Huntington's Disease** The following pedigree illustrates the inheritance pattern of Huntington's disease, a fatal genetic disorder characterized by neurodegeneration. As the signs and symptoms often do not manifest until adulthood, carriers may unknowingly pass on the disease-causing allele. The pedigree below reflects a family with members affected by Huntington's disease. **Key Features of the Pedigrees:** (a) *Autosomal Recessive Trait* - The diagram displays a typical autosomal recessive inheritance pattern, where individuals must inherit two copies of the recessive allele to express the trait. - Important notes in the diagram: - Either I-2 or I-4 must be heterozygous. - Recessive traits often skip generations. - Recessive patterns generally show up only when both parents carry the recessive allele. (b) *Autosomal Dominant Trait* - This portion shows an autosomal dominant trait, where only one copy of the allele is needed to express the disorder. - Important notes in the diagram: - I-1 is heterozygous for the dominant allele. - Dominant traits seldom skip generations, with affected individuals appearing in each generation. - Every affected individual possesses at least one affected parent. - Affected individuals will all have the dominant allele. - The dominant allele displays readily in both sexes across generations. These diagrams illustrate genetic inheritance patterns crucial for understanding Huntington’s disease in families.
a. Using just the information on this pedigree, is Huntington's disease caused by a dominant allele or recessive alleles?

b. What are the genotypes of the grandparents (I-1 and I-2)?

c. What are the genotypes of the parents (II-6 and II-7)?

d. If the parents above have another child, what is the chance that they will be affected by the Huntington’s disease allele?

e. What are the genotypes of the unaffected children (III-8, 9, 10)?

f. What is the chance that the unaffected children above will pass on a Huntington’s disease allele to their children?

g. What is the genotype of the affected child (III-11)?

h. What is the chance that the affected child above will pass on the Huntington’s disease allele to a child?
Transcribed Image Text:a. Using just the information on this pedigree, is Huntington's disease caused by a dominant allele or recessive alleles? b. What are the genotypes of the grandparents (I-1 and I-2)? c. What are the genotypes of the parents (II-6 and II-7)? d. If the parents above have another child, what is the chance that they will be affected by the Huntington’s disease allele? e. What are the genotypes of the unaffected children (III-8, 9, 10)? f. What is the chance that the unaffected children above will pass on a Huntington’s disease allele to their children? g. What is the genotype of the affected child (III-11)? h. What is the chance that the affected child above will pass on the Huntington’s disease allele to a child?
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