patterns of inheritance Flashcards
what is a pedigree drawing
most effective way of capturing info about a patient and their family
how are men demonstrated
as squares
how are women demonstrated
as circles
what are the characteristics of inheritance patterns for autosomal dominant
- most have an affected parent
- males and females equally likely to inherit and be affected
- risk for child is half
what is penetrance
percentage of individuals who carry the mutation and develop symptoms of the disorder
example of penetrance disorder
breast cancer
define variable expressivity
variation in severity/symptoms of disorder between individuals with same mutations
define somatic mosaicism
new mutations arising at early stage in embryogenesis. present in only some tissues/cells
what is germ line mosaicism
new mutation arising during oogenesis or spermatogenesis
describe autosomal recessive inheritance
manifest in homozygous/compound heterozygous form carriers not affected both sexes affected transmission both ways male to female one generation affected
define consanguinity
cousin marriages/sharing blood
describe compound heterozygous
2 mutations in the same gene, mutations are different
f508 and G542X
describe compound homozygous
2 mutations in same gene, identical mutations
F508, F508 (may be consanguinity)
features of autosomal recessive inheritance
found in clusters of siblings
recurrence risk 1/4
carrier prob2/3 for unaffected siblings of affected person
what chromosomes do men and women have
women = XX men = XY
is x linked inheritance recessive
can be, women are carriers and unaffected, no male to male transmission
aspects of X linked recessive inheritance
X linked genes never pass from father to son
all daughters of affected male are obligate carriers
kids of carrier female = 50% chance of inheriting mutant allele
explain Y linked inheritance
passed from fathers to join
e..g. hairy ears
define mutation
change in genetic material
due to alteration of function of gene product and can cause a disease phenotype
describe silent or synonymous base substitution
silent mutation = nucleotide change leads to amino acid change
point mutation = missense described
non synonymous
change in DNA sequence leading to diff amino acid being incorporated
describe impact of amino acid substitution
physiochemical similarity between two amino acids
functional role of specific domain of protein
phylogenetic conservation of original amino acid amongst diverse species
what does a point mutation cause
premature stop codon being incorporated
what’s an inframe
insertion of a base in multiple of 3
what’s a frame shift
insertion of base not in multiple of 3
