Clinical Genetics and pregnancy 2

Question 1

generally speaking what are:

• Chromosome Analysis or Array CGH
• FISH or DNA analysis

Answer 1

• general analysis of the genome (suspect diagnosis)

- need to know a diagnosis, this tells you where to look

Question 2

at which US scans might different abnormalities be detected? (4)

Answer 2

booking scan 10-12 wks
detailed scan at 20 wks
Cardiac (12-20)
Microcephaly (after 22 wks)
Short limbs (after 22 wks)
brain malformations

Question 3

what is pre implantation genetic diagnosis?

• describe the process
• disadvantages
• advantages
• when is it considered?

Answer 3

to perform a genetic test on an embryo before re-implanting one with the correct genotype

-down regulation
Ovarian stimulation-FSH
US and follicular assessment 
Oocyte retrieval
Fertilisation by ICSI
do an embryo biopsy at day 3 post fertilisation 
can determine sex using FISH

-IVF like procedure: expensive & invasive
Overall 30% take home baby rate per cycle

-less likely to have TOP
pregnancy less likely to be affected from outset

-robertsonian/reciprocal translocation
X-linked disorders
CF, Huntingtons, spinal muscular atrophy

Question 4

state the options available to parents at risk of a pregnancy affected by a genetic disorder

Answer 4

Have no further children
Take a chance
Prenatal testing
Gamete donation
Adoption
Preimplantation diagnosis