patterns of inheritance

Question 1

what is a pedigree drawing

Answer 1

most effective way of capturing info about a patient and their family

Question 2

how are men demonstrated

Answer 2

as squares

Question 3

how are women demonstrated

Answer 3

as circles

Question 4

what are the characteristics of inheritance patterns for autosomal dominant

Answer 4

• most have an affected parent
• males and females equally likely to inherit and be affected
• risk for child is half

Question 5

what is penetrance

Answer 5

percentage of individuals who carry the mutation and develop symptoms of the disorder

Question 6

example of penetrance disorder

Answer 6

breast cancer

Question 7

define variable expressivity

Answer 7

variation in severity/symptoms of disorder between individuals with same mutations

Question 8

define somatic mosaicism

Answer 8

new mutations arising at early stage in embryogenesis. present in only some tissues/cells

Question 9

what is germ line mosaicism

Answer 9

new mutation arising during oogenesis or spermatogenesis

Question 10

describe autosomal recessive inheritance

Answer 10

manifest in homozygous/compound heterozygous form 
carriers not affected
both sexes affected
transmission both ways male to female 
one generation affected

Question 11

define consanguinity

Answer 11

cousin marriages/sharing blood

Question 12

describe compound heterozygous

Answer 12

2 mutations in the same gene, mutations are different

f508 and G542X

Question 13

describe compound homozygous

Answer 13

2 mutations in same gene, identical mutations

F508, F508 (may be consanguinity)

Question 14

features of autosomal recessive inheritance

Answer 14

found in clusters of siblings
recurrence risk 1/4
carrier prob2/3 for unaffected siblings of affected person

Question 15

what chromosomes do men and women have

Answer 15

women = XX
men = XY

Question 16

is x linked inheritance recessive

Answer 16

can be, women are carriers and unaffected, no male to male transmission

Question 17

aspects of X linked recessive inheritance

Answer 17

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

Question 18

explain Y linked inheritance

Answer 18

passed from fathers to join

e..g. hairy ears

Question 19

define mutation

Answer 19

change in genetic material

due to alteration of function of gene product and can cause a disease phenotype

Question 20

describe silent or synonymous base substitution

Answer 20

silent mutation = nucleotide change leads to amino acid change

Question 21

point mutation = missense described

Answer 21

non synonymous

change in DNA sequence leading to diff amino acid being incorporated

Question 22

describe impact of amino acid substitution

Answer 22

physiochemical similarity between two amino acids
functional role of specific domain of protein
phylogenetic conservation of original amino acid amongst diverse species

Question 23

what does a point mutation cause

Answer 23

premature stop codon being incorporated

Question 24

what’s an inframe

Answer 24

insertion of a base in multiple of 3

Question 25

what’s a frame shift

Answer 25

insertion of base not in multiple of 3