clinical genetics and pregnancy Flashcards
which types of DNA analysis are available, from large mutation to small mutation
chromosome analysis
aCGH - for deletions/duplications
PCR and Sanger sequencing
next generation sequencing
when does the booking scan normally take place
10-12 weeks
wen does the detailed ‘anomaly’ scan take place
20 weeks
what does the detailed scan detect
specific anomalies cardiac microcephaly short limbs brain malformations
what is the risk of a new child being affected by an x-linked disease
1 in 4
1 in 2 if male
what is the risk of a new child being affected by an autosomal dominant disease
50%
what is the risk of a new child being affected by an autosomal recessive disease
1 in 4
when can chorionic villus biopsy be performed
11.5 weeks
when can amniocentesis be performed
at 16 weeks
how long do PCR results take
2-3 days
what is PGD
pre-implantation genetic diagnosis
perform genetic test o an embryo before implanting one with the ‘correct’ genotype
what are the current options available if you are at risk of having a child affected by a genetic disorder
have no children take a chance prenatal testing gamete donation adoption preimplantation diagnosis
who offers PGD
centres must be licensed by the HFEA in accordance with the HFE ACT 1990
how can PGD be carried out
FISH
different coloured probes to label chromosome X, Y and 18 (control)
individual chromosomes are not visible
what are the cons of PGD
requires an IVF-like procedure
30% success rate per cycle
DNA analysis less reliable than prenatal testing (analysis of a single cell)
multiple pregnancy risk
