Question 1

Which of the following is the correct HGVS nomenclature for a substitution of adenine to thymine at nucleotide 67 in the coding DNA sequence?

Accepted Answer

$$c.67A\u003eT$$

Question 2

A patient is found to have a variant described as p.(Gly144Val) in the FH gene. What does this notation indicate?

Accepted Answer

A glycine at position 144 in the protein is replaced by valine.

Question 3

Which of the following best describes a frameshift mutation?

Accepted Answer

An insertion or deletion of nucleotides not divisible by three, altering the reading frame.

Question 4

A variant is described as c.76_78del. What does this mean?

Accepted Answer

Nucleotides 76 to 78 are deleted.

Question 5

Which of the following is a possible consequence of a nonsense mutation?

Accepted Answer

Premature introduction of a stop codon, leading to a truncated protein.

Question 6

What is the effect of a mutation at a splice donor site (e.g., c.77+1G\u003eT)?

Accepted Answer

It can disrupt normal splicing, potentially leading to exon skipping or intron retention.

Question 7

Which of the following is the correct description for a variant at the protein level that does not change the amino acid sequence?

Accepted Answer

Silent (synonymous) mutation

Question 8

A variant is described as c.485_488del. What is the most likely effect at the protein level?

Accepted Answer

Frameshift

Question 9

Which of the following codons is a stop codon in the standard genetic code?

Accepted Answer

$$\mathrm{UAA}$$

Question 10

A patient has a variant described as c.76_77insT. What does this mean?

Accepted Answer

A T is inserted between nucleotides 76 and 77.

Question 11

Which of the following best describes the effect of a missense mutation?

Accepted Answer

A single amino acid is changed to another.

Question 12

What is the correct nomenclature for a duplication of T at position 76 in the coding sequence?

Accepted Answer

$$c.76dupT$$

Question 13

Which of the following is a possible outcome of a mutation that activates a cryptic splice site?

Accepted Answer

Partial exon deletion or inclusion of intronic sequence in mRNA

Question 14

A variant is described as c.586_588dup. What is the most likely effect at the protein level?

Accepted Answer

In-frame duplication

Question 15

Which of the following is the correct description for a variant that changes an arginine to a stop codon at position 196?

Accepted Answer

Nonsense mutation

Genetic Variant Nomenclature and Interpretation: Study Notes for Genetics Students

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