Chromosome Analysis

Question 1

What are some methods of detecting point mutations?

Answer 1

• DNA sequencing which can be done via Sanger sequencing (looks at 1 gene at a time, older method) or Next Generation/Massively Parallel sequencing (newer method which looks at many genes).
• ARMS PCR (Analysis specific known mutation points)

Question 2

What are some methods of looking at sub-microscopic duplications and deletions?

Answer 2

Needed when under 4 million base pairs.
- MLPA (PCR method that targets groups of specific known positions - must know position)
- Chromosomal micro-array (genome wide - used when don’t know position)
- FISH (specific DNA probe that binds to some location on chromosome, however this requires knowledge of position on chromosome where gene may be missing)

Question 3

Describe methods of rapid detection of aneuploidies

Answer 3

-QF PCR (rapidly looks for specific aneuploidies)
-Karyotyping (examining chromosomes under microscope)

Question 4

What can next generation sequencing analyse?

Answer 4

• Single gene,
• Several genes,
• Exomes (protein coding regions)
• Entire genome

Question 5

Explain in a bit more detail how next generation sequencing can be carried out

Answer 5

DNA is analysed via NGS using a machine such as illumina. This produced a FASTQ file (raw data), a computer programme will align the sequence against a referencing genome to produce a BAM file. Variants are identified and a VCF file is produced. Data filtering removes common variants