Mendellian pedigree patterns #5-6 Flashcards
what is a pedigree chart used for?
to study the transmission of a hereditary condition
consultand
a person who wants genetic counselling
proband
a person who a genetic counselling is done for
what are the 5 basic patterns of inheritance?
~autosomal dominant ~autosomal recessive ~x-linked dominant ~X-linked recessive ~Y-linked
how to determine AD inheritance
~affected individual has an affected parent
~affected parent + unaffected parent have = # of affected and unaffected offspring
~unaffected children of an affected parent do not transmit to their children
~males and females are equally likely to be affected
how to attribute genotypes in AD
1- all affected by Aa
2- all unaffected by AA
3- all III-IV gen AA
what 2 things must we consider when assigning genotypes?
age of onset and penetrance
examples of AD diseases
brachydactylyl polydactylyl achondroplasia - dwarfism Huntington's marfans syndrome - CT neurofibromatosis
how to determine AR inheritance
~males and females equally likely to be affected
~all children of 2 affected parents are affected
~all children of an affected parent and normal parent are heterozygotes
~children of heterozygotes are 25% affected, 50% carriers, 25% normal
how to attribute genotypes in AR
1- all affected are aa
2- all carriers are Aa
3- all external ppl are AA
examples of AR diseases
cystic fibrosis
sickle cell anemia
phenylketonuria
rules of X-linked dominant are
~trait is common on the pedigree
~affected father transmits disease to all daughters
~fe/males are equally affected
Examples of X-dominant
fragile X syndrome
alport syndrome
rules of X-linked recessive are
~more males than females affected ~affected son can have normal parents ~affected female should have an affected father and carrier mother ~skipping of generations ~affected mother = all affected sons
XR diseases
hemophilia A
hemophilia B
color blindness
