QuestionSBA
QuestionChoice
In this scenario, the child inherited his condition from his father. Mitochondrial conditions are always inherited from the mother, as all mitochondria of the foetus are maternal.
10006740
e
Mitochondrial
QuestionChoice
With autosomal dominant conditions, the disease can manifest in a heterozygous state. In this scenario, the child is heterozygous and inherited his condition solely from his father.
10006736
a
Autosomal dominant
QuestionChoice
These are caused by a mutation on the X-chromosome. 100% incidence of affected sons from an affected mother suggests X-linked recessive. In this scenario, the child’s brother is unaffected and it was inherited from his father, who would have been unable to pass on his affected X-chromosome.
10006739
d
X-linked recessive
QuestionChoice
These are caused by a mutation on the X-chromosome. 100% incidence of affected daughters from an affected father suggests X-linked dominance. In this scenario, as it is the child’s father who is affected, if it was an X-linked condition he would not be able to pass the affected X-chromosome to his son, as he would receive the Y-chromosome.
10006738
c
X-linked dominant
QuestionChoice
With autosomal recessive conditions, the disease manifests in only a homozygous state. In this scenario, the child is heterozygous and so cannot be autosomal recessive.
10006737
b
Autosomal recessive
Concept
Chapter
2693
3891
Genetic Inheritance
Topic
156
Medical Genetics
13894
A three-month -old boy is found to be positive for a genetic disease. He is heterozygous for the condition, as well as his father who is also affected by the disease. His mother and older brother do not possess the mutated gene.

What is the most likely mode of this genetic inheritance?
a