Female is affected, male is not. Disease is autosomal dominant, what is the chance in children?
**Core Concept:** Autosomal Dominant Disorders
Autosomal dominant disorders are genetic conditions that are inherited in this manner. In such disorders, an affected parent has a 50% chance of passing the abnormal gene to their offspring, regardless of sex. This means that if a female carries the abnormal gene, she has a 50% chance of passing it to her child, regardless of the child's sex.
**Why the Correct Answer is Right:**
In an autosomal dominant inheritance pattern, the sex of the parent does not influence the sex of the child affected. In this case, the disease is affecting females more than males, but the mode of inheritance remains the same. When a mother carries the gene mutation (A), she has a 50% chance of passing the mutation to her child, regardless of the child's sex. Among the offspring, there is an equal distribution of carriers (having the gene mutation) and non-carriers (having normal genes).
**Why Each Wrong Option is Incorrect:**
A. This option suggests that the sex of the parent influences the sex of the affected child, which is incorrect in an autosomal dominant inheritance pattern.
B. This option implies that the sex of the child is affected by the sex of the parent, which is not the case in autosomal dominant disorders.
C. This option suggests that the sex of the child will be the same as the parent, which is incorrect in an autosomal dominant inheritance pattern.
D. This option suggests that the sex of the child will be the same as the parent, which is incorrect in an autosomal dominant inheritance pattern.
**Clinical Pearl:**
In autosomal dominant disorders, the sex of the parent does not affect the chance of the child being affected or having the abnormal gene. Understanding this concept is crucial in genetic counseling and predicting disease risks in families with a history of these disorders. When a parent with an autosomal dominant disorder has a male child, the child has a 50% chance of inheriting the abnormal gene and a 50% chance of receiving two normal genes. Therefore, the sex of the child does not influence the disease risk.