Mutations and Genetic Analysis

Question 1

Types of mutations

Answer 1

1. Non-coding
2. Coding; silent/synonymous (CGA (Arg) to CGC (Arg)), missence (CGA (Arg) to GGA (Gly)), nonsense (CGA (Arg) to TGA (stop)), frameshift deletion or insertion (CGA (Arg) to CCGA (pro, out of frame).
3. Point mutations; transitions (purine to purine or pyrimidine to pyrimidine) or transversions (purine to pyramidine.

Question 2

Effects of mutations

Answer 2

1. Numerical abnormalities; too few or too many chromosomes. E.g. trisomy - 21 chromosome - Down Syndrome. These lead to dysmorphic features, mental retardation, developmental problems, sex chromosome aneuploidy syndromes e.g. Turner syndrome - 45X
2. Structural abnormalities; (un)balanced rearrangements, deletions, inversions, reciprocal or Robertsonian translocations, insertions.
3. Genetic mutations; germline or somatic, gene disrupted/disease associated, polymorphism (no phenotypic effect, frequency less that 1%).

Question 3

Molecular genetic technology used to identify genetic mutations.

Answer 3

1. Polymerase Chain reactions (PCR); 3 steps denature, anneal, extend.
2. Gel electrophoresis
3. Restriction fragment length polymorphism (RFLP) analysis
4. Amplification refractory mutation system (ARMS)
5. DNA sequencing