Your mother has Huntington's disease, an autosomal dominant disorder. Your father is not diseased. You get tested and find out you are homozygous recessive. Your mother's genotype was: 1) HH 2) Hh 3) hh

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**Understanding Huntington's Disease and Genetic Inheritance**

Huntington's disease is an autosomal dominant disorder, meaning that only one copy of the defective gene, inherited from an affected parent, is necessary for a person to be at risk of developing the disease. If your mother has Huntington's disease and your father is not diseased, and you are found to be homozygous recessive (having two copies of the normal gene), this provides insight into your mother’s genotype.

**Question:**
Given that your mother has Huntington's disease, an autosomal dominant disorder, and your father is not diseased, and you find out that you are homozygous recessive, what was your mother’s genotype?

1. HH
2. Hh
3. hh
4. XHXH
5. XHXh
6. XhXh
7. XHY
8. XhY
9. Cannot be determined from information provided

**Detailed Explanation:**
- HH: This option represents a genotype where the individual possesses two copies of the dominant allele. Since Huntington’s disease is dominant, an individual with this genotype would not pass any normal (recessive) allele to their offspring. Since you are homozygous recessive, your mother cannot be HH.
- Hh: This option represents a genotype where the individual possesses one copy of the dominant allele (H) and one copy of the recessive allele (h). Given that you are homozygous recessive (hh), your mother must have passed one recessive allele (h) to you. This is consistent with a mother having the Hh genotype.
- hh: This genotype represents an individual possessing two copies of the recessive allele, meaning they would not have Huntington's disease. Thus, this cannot be your mother’s genotype.
- XHXH, XHXh, XhXh, XHY, XhY: These options represent genotypes related to X-linked disorders, which are not relevant to the autosomal dominant inheritance pattern of Huntington's disease.

**Conclusion:**
Based on the given information, your mother's genotype was most likely **Hh** (Option 2), as this is the only scenario that aligns with both her having Huntington's disease and the possibility of you being homozygous recessive.

This understanding is vital when studying human genetics and the inheritance of autosomal dominant disorders such as Huntington's disease.
Transcribed Image Text:**Understanding Huntington's Disease and Genetic Inheritance** Huntington's disease is an autosomal dominant disorder, meaning that only one copy of the defective gene, inherited from an affected parent, is necessary for a person to be at risk of developing the disease. If your mother has Huntington's disease and your father is not diseased, and you are found to be homozygous recessive (having two copies of the normal gene), this provides insight into your mother’s genotype. **Question:** Given that your mother has Huntington's disease, an autosomal dominant disorder, and your father is not diseased, and you find out that you are homozygous recessive, what was your mother’s genotype? 1. HH 2. Hh 3. hh 4. XHXH 5. XHXh 6. XhXh 7. XHY 8. XhY 9. Cannot be determined from information provided **Detailed Explanation:** - HH: This option represents a genotype where the individual possesses two copies of the dominant allele. Since Huntington’s disease is dominant, an individual with this genotype would not pass any normal (recessive) allele to their offspring. Since you are homozygous recessive, your mother cannot be HH. - Hh: This option represents a genotype where the individual possesses one copy of the dominant allele (H) and one copy of the recessive allele (h). Given that you are homozygous recessive (hh), your mother must have passed one recessive allele (h) to you. This is consistent with a mother having the Hh genotype. - hh: This genotype represents an individual possessing two copies of the recessive allele, meaning they would not have Huntington's disease. Thus, this cannot be your mother’s genotype. - XHXH, XHXh, XhXh, XHY, XhY: These options represent genotypes related to X-linked disorders, which are not relevant to the autosomal dominant inheritance pattern of Huntington's disease. **Conclusion:** Based on the given information, your mother's genotype was most likely **Hh** (Option 2), as this is the only scenario that aligns with both her having Huntington's disease and the possibility of you being homozygous recessive. This understanding is vital when studying human genetics and the inheritance of autosomal dominant disorders such as Huntington's disease.
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