The future of genomic Medicine

Question 1

Describe pre-implantation genetic diagnosis process

Answer 1

1. Stimulation of the ovaries- stimulate the ovaries to produce more eggs. 2. eggs are collected 3. Insemination - either by IVF ( sperm and egg placed together in a culture dish) or ICSI ( intra-cytoplasmic sperm injection - injection of a single sperm into each egg) 4. Fertilisation 5. Embryo Biopsy- once embryo gets to about 8 cells in size, a cell is removed by embryo biopsy 6.Embryo testing 7. Embryo Transfer- embryos that don’t have the genetic condition or are carriers are considered for embryo transfer ( max 2 transferred) 8. Pregnancy test

Question 2

How many base pairs are there in the complete human genome?

Answer 2

6 billion

Question 3

What is the easiest way to diagnose a monogenic disease when we know the mutation, give an example

Answer 3

Cystic fibrosis.
Use PCR;
identify the 3 base deletion.
DeltaF508

Question 4

What happens if we dont know the mutation, what method can we use

Answer 4

Use sanger sequencing:
PCR of the genomic fragment
label them with fluorecent labels
clean 
identify the specific nucleotide in the sequence
and identify specific nucleotide changes

Question 5

When do we use next generation sequencing (NGS) over Sanger sequencing

Answer 5

When we need to sequence a huge amount of fragments we use next generation.

Sanger: only sequence one fragment at a time
Next generation: can sequence a million of sequence at one time
if we need a lot of data we use NGS.
BUT if we know which sequence we need then Sanger sequencing is cheaper.

Question 6

What are SNPs?

Answer 6

Single nucleotide polymorphisms.

Each person has 3 million SNPs.

Question 7

What is Preimplantation genetic diagnosis

Answer 7

PGD is a genetic test carried out on IVF embryos before implantation.

• PGD ensures that only embryos that are free of a certain genetic condition are returned to the womb,
• PGD is available to families at risk of having a child affected by a serious genetic condition.

Question 8

What genetic tests can be done in PGD

Answer 8

• Fluorescence In Situ Hybridisation: detects chromosomal conditions e.g. Down Syndrome
• PCR and DNA sequencing: detects mutations in single genes

Question 9

What are some of the ethical issues of PGD

Answer 9

• involves discarding unused embryos
• disability rights argument
• slippery slope: designer babies
• Eugenics:improving a population by controlling breeding to increase the occurrence of desirable characteristics.

Question 10

What are some of limitations of PGD?

Answer 10

IVF- physically and emotionally demanding: expensive

• only suitable for diseases where the genetic/chromosomal abnormality is known
• can only select for traits that are present/absent in the embryos obtained- cant design the baby