QuestionSBA
QuestionChoice
This is incorrect. There are times when a person will be the first person in their family to have the specific mutation (de novo). This can occur due to a sporadic mutation.
10025793
d
There is always a family history of autosomal dominant disorders
QuestionChoice
This is incorrect. If one parent carries the abnormal allele of an autosomal dominant condition, the chance of a child inheriting the allele and becoming a carrier is 50%. If Aa is the affected parent and aa is the unaffected parent: Aa, Aa, aa and aa are the possible allele combinations. 2 out of 4 of these are affected and therefore the chance is 50%.
10025792
c
There is 100% chance of a child inheriting an autosomal dominant condition if only one parent carries the gene
QuestionChoice
This is incorrect. Males and females are equally affected. This statement would be true of x-linked recessive conditions; as males only have one x chromosome, if they inherit a pathogenic variant of x-linked recessive condition then they will be affected.
10025794
e
Only males can be affected
QuestionChoice
This is correct. In autosomal dominant conditions, only one copy of the gene is needed for the individual to be symptomatic. This means that any patient with the abnormal allele will always be both a carrier and a sufferer. It also means that only one parent has to be a sufferer to pass on the condition.
10025790
a
Only one abnormal copy of a gene is needed for an individual to be symptomatic
QuestionChoice
This is incorrect. In autosomal dominant conditions, if one parent carries the faulty gene there is a 50% chance that their offspring will inherit it, and in turn become symptomatic.
10025791
b
Both parents must have a copy of the abnormal gene for the child to be symptomatic
Concept
Chapter
2693
5863
Autosomal dominant conditions
Topic
156
Medical Genetics
17556
A 20 year old woman receives a new diagnosis of Ehlers-Danlos syndrome. Her GP explains that this is an autosomal dominant condition.

Which of the following is true of autosomal dominant conditions?
a