Pedigrees and Risk Flashcards
What is a pedigree chart?
A diagram which shows the presence or absence of a trait within a family across generations, used to analyse the pattern of inheritence through a family
What symbol is used to show a male?
Square
What symbol is used to show female?
Circle
What is used to show a person who is affected?
Coloured in circle
How is the difference between X linked Carrier and Autosomal carrier shown on a pedigree chart?
X linked carrier has a dot in the middle, autosomal has half the shape shaded
How is a consanguineous couple shown on a pedigree chart?
Double lines connecting the male and female
What is the difference between monozygotic and dizygotic twins?
Monozygotic are identical, dizygotic are not
If only females are affected, which type of inheritance is it ilkely to be?
Mitochondrial
If only males are affected, which type of inheritance is it likely to be?
Y linked
If unaffected parents can have affected children, is the pattern of inheritance for that condition likely to be dominant or recessive?
Recessive
If affected parents can have unaffected children, is the pattern of inheritance for that condition likely to be dominant or recessive?
Dominant
If the condition is more common in females, which type of inheritance does it tend to be?
X-linked dominant - affected males transmit to all daughters
If the condition is more common in males, which type of inheritance is it likely to be?
X-linked recessive - affected females transmits to all sons
Why is calculating risk useful?
It allows parents to make an informed decision as to whether they want to start a family or not given the risk of certain conditions
Describe, in detail, the social and cultural issues related to
stigma and bias that might impact upon their decision when deciding whether or not to start a family
A recognition that the couple might be hesitant to seek medical advice at this
point, due to a sense of shame/stigma surrounding sickle and a desire not to mark
oneself out as ‘different’ or ‘disadvantaged’ (1 mark).
Recognition of the potential unconscious bias of the medical professional when
carrying out a consultation (1 mark).
Mention of the historical roots of such stigma (1 mark).
Students might cite the scientific racism of the 19th century that argued for
quantifiable biological and anatomical differences between the black and white