Chromosome Analysis, DNA Analysis and Clinical Genomics

Question 1

• How is PCR undertaken?

Answer 1

• Two oligonucleotide primers direct repeated cycles of localised DNA replication to produce an exponential increase in the number of copies of a target sequence
• Each cycle contains three steps; denaturation (renders DNA single stranded), primer annealing and strand elongation

Question 2

How are PCR products checked?

Answer 2

• QF-PCR (abnormal number of chromosomes)
• ARMS (detection of point mutations)
• MLPA (detection of sub-microscopic duplications and deletions)

Question 3

• What is Sanger DNA sequencing?

Answer 3

• PCR-like reaction with single primer
• Utilises DNA template to generate series of detachable single-stranded fragments of increasing length which can be split and identified
• Can only look for one known sequence at a time

Question 4

What is aCGH?

Answer 4

• Microassays of thousands of DNA sequences, spaced at intervals along chromosomes, spotted onto slides
• Subject’s DNA labelled green and reference gene labelled red
• Mixture is hybridised and scanner by a laser with the green:red ratio indicating abundance of subject vs reference