8C- pedigree analysis Flashcards
horizontal lines
mating between two individuals
vertical lines
link between two generations
circles
females
squares
males
coloured
affected
uncoloured
unaffected
double horizontal lines
consanguieneous breeding
autosomal dominant traits
1 If both parents are affected, the offspring may be unaffected.
2 If neither parent is affected, the offspring must be unaffected.
3 If an offspring is affected, there must be an affected parent.
4 The trait cannot skip a generation.
autosomal recessive
1 If both parents are affected, the offspring must be affected.
2 If neither parent is affected, the offspring may be unaffected.
3 If an offspring is affected, there may be an affected parent.
4 The trait can skip a generation.
x linked dominant
1 If a male is affected, his mother must be affected.
2 If a male is affected, his daughters must be affected.
3 If a female is unaffected, her father must be unaffected.
4 If a female is unaffected, her sons must be unaffected.
5 The trait cannot skip a generation.
Sex-linked inheritance cannot be confirmed with certainty using just a pedigree.
x linked recessive
1 If a female is affected, her father must be affected.
2 If a female is affected, her sons must be affected.
3 If a male is affected, his mother may be affected.
4 The trait can skip a generation.
Sex-linked inheritance cannot be confirmed with certainty using just a pedigree.
y linked
1 Only males can show the trait.
2 All males in a lineage will show the same phenotype.
3 The trait cannot skip a generation.
Sex-linked inheritance cannot be confirmed with certainty using just a pedigree.
examples of autosomal dominant traits
Huntington’s disease, achondroplasia (dwarfism)
examples of autosomal recessive traits
Cystic fibrosis, Tay-Sachs disease, albinism, phenylketonuria (PKU)
examples of x linked dominant traits
Rett syndrome, fragile X syndrome
