Prenatal Flashcards
% major Fetal abns related to Chr abnormalities
20-25%
% improvement the detection rate of Chr abns using aCGH over largo typing
4-6%
Study comparing 5 array platforms
Huang and Crolla. 2010. Comp 5 array platforms and software- 12 samples- all needed comparable Dan concn. and DR=93-100%
Key aim with use of aCGH in prenatal setting
Need balance of optimal resolution and coverage. Targeted/low res array will miss abns and higher density will increase cnvous
Advantage of using aCGH in prenatal so
No culture req- increase tat, decrease cultural artefact, better DR, pick up cryptics
Disadvantage of prenatal aCGH
Poor quality and quantity of dna , miss balanced rea, miss lower level mosaic, triploidy missed,still need culture for f/u fish, cnvous->anxiety, counselling issues ass with cnvous and inc penetrance
How many extra cyto cryptic abnormalities are seen on aCGH
1-3% in some studies
What are prenatal aCGH best practice guidelines
None specifically, guidelines based on results of EACh study
Hillman et al 2011 reviewed outcomes of pCNV in prenatal setting- what are they?
12% cnv seen in all foetuses (3.6% were pathogenic), 11.2% cnv seen in abscan referrals (5.2% pathogenic)
When should a deletion of an autosomal recessive condition be reported
Only if carrier freq is high. Consider late onset with clinical utility
Definition of screening
Process to ID apparently healthy people at an increased risk of a condition. Can then be offered further tests or treatment to decrease risk and/or complications
3 considerations of effective screening
High DR, low FPR, low FNR
By 2010 all nhs trusts were expected to provide what DR and FPR for aneuploidy screen
> 90% dr and
What is the FASP
Fetal anomaly screening prog.overseen by uknsc.
Risk of trisomy 21 at 49 years
1:85
Risk if T21 at 30
1:940
Risk if T21 at 20
1:1450
Risk if T21 at 35
1:350
What was the DR for a 5% FPR when using maternal age only
DR 30%
What is the current DS screening uptake (according to RAPID)
66%
What is national target for timescale of offering one for high risk screen patients
97% in 3 days
what is MoM
Multiple of mean
How is MoM calculated
Concentration of marker for a patient divided by concentration of that marker in general popn
What is measured in triple test
Afp, beta hcg and uE3
