2.4 Flashcards
what are antenatal screening methods used to do
to identify the risk of disorders in a foetus or embryo before it’s born
when are dating scans carried out
at 8-14 weeks
what do dating scans do
determine the pregnancy stage and due date
when are anomaly scans carried out
18-20 weeks
what do anomaly scans do
detect serious physical abnormalities in the foetus
why are routine blood and urine tests carried out throughout pregnancy
to monitor concentrations of marker chemicals
what does measuring a chemical at the wrong time lead to
a false positive result
what can atypical chemical concentrations lead to
diagnostic testing to determine if the foetus has a medical condition
when would a diagnostic test be carried out
after a screening test
why would a diagnostic test be carried out
to definitely establish whether or not the person has the condition or disorder
what is a karyotype
an image of an individuals chromosomes arranged in homologous pairs
how are karyotypes produced
cells from samples can be cultured to obtain sufficient cells
what would a karyotype be used for
to diagnose a range of conditions
what does postnatal screening involve
health checks which are carried out after the birth of a baby
how would you detect PKU in a baby
postnatal screening
what causes pku
a substitution mutation meaning that the enzyme which converts phenylalanine into tyrosine is non functional
what happens to individuals with high levels of phenylalanine (pku)
they are placed on a restricted diet
what is a pedigree chart
a family tree
what are pedigree charts used to do
to analyse patterns of inheritance in genetic screening and counselling
why do genetic counsellors use pedigree charts
to advise parents of the possibility of passing on a genetic condition to their child
which chromosome is the sex chromosome
the 23rd pair
what is the name for the other 22 chromosomes
autosomes
