QuestionSBA
QuestionChoice
This is seen in trinucleotide repeat expansion disorders such as Fredrich's ataxia.

This case describes worsening of disease severity and duration with increasing generations. This is due to the expansion of the region of triplet base repeats.
10005876
a
Anticipation
QuestionChoice
The mitochondrial DNA is only inherited from the mother. Therefore if the mother is affected by a condition 100% of offspring will be affected. If the father is affected by the condition, no offspring will be affected.
10005880
e
Mitochondrial Inheritance
QuestionChoice
This is where both alleles for a gene are expressed.

For example a flower that have red and white flowers formed from a purely white flowered plant and purely red flowered plant.

This is different from incomplete dominance, where an intermediate is formed such as pink flowers.
10005879
d
Codominance
QuestionChoice
Fredrich's ataxia is inherited in an autosomal recessive way which means two alleles are required to express the gene and develop this condition.

However, this case is describing anticipation which is where there is an earlier, more severe presentation of the disease with increasing generations due to amplification of the mutation.
10005877
b
Autosomal recessive inheritance
QuestionChoice
This refers to an autosomal dominant trait that is only partially expressed.

For example, if one parent has straight hair and one parent has curly hair, incomplete dominance in the child could be wavy hair. This is an intermediate of the two alleles.
10005878
c
Incomplete dominance
Concept
Chapter
2693
4455
Genetic Mechanisms
Topic
156
Medical Genetics
13722
A 7 year old child is recently diagnosed with Fredrich's ataxia and is struggling to carry out everyday activities such as washing and dressing. The parents are concerned that he may even need a wheelchair in a few years.

The father states that the child's symptoms are developing much faster than his father's.

Why is the boy's symptom onset worse than his grandfather who had the same condition?
a