Mendelian Genetics

Question 1

what did gregor mendel use to observe simple characteristics

Answer 1

pure breeding lines

Question 2

how many characteristics mendel observe

Answer 2

seven

Question 3

normal or wild type refers to what

Answer 3

the most common allele in a given population

Question 4

single gene disorders are also known as

Answer 4

mendelian or monogenic diseases

Question 5

single gene disorders are caused by mutations in

Answer 5

one gene

Question 6

what can pedigree analyses of large families with many affected individuals tell us about a monogenic disease?

Answer 6

whether it is located on an autosome, sex chromosome, whether it is dominant or recessive

Question 7

individuals are called heterozygotes and with one copy of the altered gene they are affected. this is?

Answer 7

dominant

Question 8

homozygotes must have two copies of the altered gene to be affected, this is?

Answer 8

recessive

Question 9

males with an altered gene on the x-chromosome are always affected, this is?

Answer 9

x linked recessive

Question 10

give some examples of autosomal dominant conditions

Answer 10

huntington disease, marfan syndrome, FAP famiilial adenomatous polyposis

Question 11

with an autosomal dominant inheritance pattern what chance is there that the child will be affected

Answer 11

50/50

Question 12

list three complications in autosomal dominant inheritacne

Answer 12

new mutations - sporadic de novo cases, variable penetrance and anticipation

Question 13

what are sporadic de novo cases

Answer 13

a new germline mutation that was not inherited from either parent

Question 14

what is variable penetrance

Answer 14

proportion of individuals with a mutation that exhibit clinical symptoms, e.g. 95% penetrance, 5% will have mutation but not have symptoms

Question 15

what is anticipation

Answer 15

genetic disorder passed onto next generation, symptoms become apparent at an earlier age and severity is also increased

Question 16

anticipation is common in which types of mutation

Answer 16

triplet repeat expansion such as Huntingtons

Question 17

with familial adenomatous polyposis the patient has to inherit a single mutant APC allele and they will

Answer 17

have the disease

Question 18

familial adenomatous polyposis is described to be what in terms of penetrance and colorectal cancer risk

Answer 18

100% penetrant, 100% CRC risk

Question 19

familial adenomatous polyposis shows what type of inheritance

Answer 19

autosomal dominant

Question 20

polyp numbers can vary depending on the

Answer 20

position of the germline mutation

Question 21

what is APC

Answer 21

a tumor suppressor in which mutations lead to colon cancer

Question 22

APC mutations are also very common in

Answer 22

sporadic CRC

Question 23

how many different mutations can occur in the APC gene

Answer 23

300 different mutations

Question 24

in the APC gene large deletions account for around

Answer 24

15% of the problem

Question 25

list some examples of autosomal recessive conditions

Answer 25

sickle cell, cystic fibrosis, congenital deafness,

Question 26

why are deleterious mutations sometimes prevalent?

Answer 26

heterozygote advantage

Question 27

with an autosomal recessive trait there is a 1 in

Answer 27

4 chance of the child having the disease

Question 28

what is consanguinity

Answer 28

(blood relation) being from the same kinship as another person - most common between first cousins

Question 29

with a recessive disease, the gene mutation comes together and causes an

Answer 29

autosomal recessive disease

Question 30

list some x linked recessive diseases

Answer 30

haemophilia, duchenne muscular dystrophy,

Question 31

in x linked recessive diseases, one copy of an altered gene on the x chromosome causes the disease in

Answer 31

males

Question 32

in a x linked recessive disease, an altered copy on one of the x chromosome pairs causes what in females

Answer 32

carrier status

Question 33

the risk of being affected with an x linked recessive disease depends on the

Answer 33

gender of the child

Question 34

carrier females have a ___ chance of having an affected son with an x linked recessive inheritance pattern

Answer 34

50%

Question 35

affected males with xlinked recessive are usually born to an _____ parent,

Answer 35

unaffected, the mother is usually an asymptomatic carrier

Question 36

with x linked recessive inheritance there is no male to

Answer 36

male transmission

Question 37

an x linked dominant condition is the dominant gene being carried on

Answer 37

an x chromosome

Question 38

in an x linked dominant condition, how many copies of the allele can cause the disorder

Answer 38

one

Question 39

if the mother is affected with an x linked dominant disorder, what is the inheritance pattern

Answer 39

50% of children will have disorder

Question 40

if the father is affected with a x linked dominant disorder, what is the pattern of inheritance for the children?

Answer 40

100% of daughters will have disorder, 0% of sons

Question 41

what does the Hardy Weinberg Distribution state?

Answer 41

that allele and genotype frequencies in a population willl remain constant from generation to generation in the absence of evolutionary influences

Question 42

single gene disorders are common or rare

Answer 42

quite rare

Question 43

most traits are

Answer 43

polygenic

Question 44

what is a polygenic disease

Answer 44

a genetic disorder that is caused by the combined action of more than one gene

Question 45

examples of polygenic diseases include

Answer 45

cancer, diabetes, alzheimers

Question 46

polygenic diseases have how many mutations

Answer 46

many (10s-100s)

Question 47

describe the penetrance in polygenic diseases

Answer 47

low, variable

Question 48

describe the penetrance in monogenic diseases

Answer 48

high

Question 49

what interaction is important in polygenic and monogeneic diseases

Answer 49

gene/environment interaction