Assessment and Screening Flashcards
Assessment of a patient in the genetics clinic involves looking for dysmorphic features. Give examples of these dysmorphic features.
macro or microcephaly palpebral fissures eye spacing ear size, shape, position and rotation nose size and nares philtrum mouth size, lips and teeth limb proportion skin lumps or abnormal pigmentation palmar creases correct number of fingers and toes
What dysmorphic features are present in Rubinstein taybi syndrome?
Down slanting palpebral fissures
Microcephaly
Broad thumbs and toes
Describe the process of PGD.
Involves the removal of one or sometimes two cells from an embryo of 3 days old which is in the blastomere stage and contains 6-10 cells
Then QF-PCR or FISH to look for mutations
Then unaffected embryos can be inserted into the uterus
How successful is pre-implantation diagnosis?
50% chance of working once a healthy embryo has been acquired
What factors could inhibit pre-implantation diagnosis?
Age
AMH level
What is sensitivity?
The number of true positives divided by the total number of affected people
What is specificity?
The number of true negatives divided by the total number of unaffected people
What technique is used for neonatal screening of phenylketonuria and MCADD?
Mass spectrometry
What technique is used for neonatal screening of congenital hypothyroidism and cystic fibrosis?
Immunoassays
What technique is used for neonatal screening of sickle cell disorder?
HPLC
What group of people are offered postnatal screening for tay Sachs disease?
Jewish people
What prenatal genetic diagnostic test can be done in the first trimester?
Chorionic villus sampling
What prenatal genetic diagnostic test can be done in the second trimester?
Amniocentesis
There is a risk of miscarriage associated with CVS and amniocentesis. Which technique carries the biggest risk for miscarriage?
CVS
Non-invasive prenatal diagnostic tests can be done privately to test for Down syndrome. What conditions might this technique be sued to detect in future?
Achondroplasia
Sex determination for x linked conditions
It is possible to detect paternal mutations present in the mothers blood through what genetic diagnostic test?
Non-invasive prenatal diagnostic testing
In the future next generation sequencing of whole exams will be available. How will current knowledge need to change to accommodate this?
We will need a better understanding of variants of uncertain significance and non-coding regions of the genome
How will genetics shape personalised medicine in the future?
Increased efficacy and safety of prescribing based on analysis of patient’s SNPs
May become possible to tailor treatment to a specific disease causing mutation
The advance of genetics will allow the further development of tailored treatments of specific disease causing mutations. What drug is currently used in cystic fibrosis patients with the G551D mutation?
Ivacaftor
What mutation specific drug is current used against certain lung cancers?
Gefitinib
What mutation specific drug is used against breast cancers with the HER2 mutation?
Trastuzumab
The technique of exon skipping may be sued in the future to treat Duchenne’s muscular dystrophy. How does this technique work?
It alters splicing patterns in order to correct the reading frame and convert DMD into the less severe BMD phenotype
Give examples of drugs which permit read-through of premature stop codons.
Ataluren
PTC124
Base editing is a possible future technique for treating genetic conditions. Give an example of a condition which this technique could treat.
Convert G back to an A in beta thalassaemia in embryos
There is a potential for off-target sites to be affected by CRISPR-CAS9 gene therapy techniques. T/F?
True
