Lecture 4: Mendelian Inheritance in humans

Question 1

Mendelian or monogenic disease=

Answer 1

If on gene is involved to cause a disease

Question 2

Multifactural disease=

Answer 2

if many genes are involved in causing the disease

Question 3

Are all mendelian characters diseases?

Answer 3

no

Question 4

how many mendelian characters are in man?

Answer 4

Over 6000

Question 5

White square

Answer 5

MALE (unaffected)

Question 6

black square

Answer 6

Male (affected)

Question 7

white circle

Answer 7

FEMALE (unaffected)

Question 8

Black circle

Answer 8

Female (affected)

Question 9

Diamond white

Answer 9

Sex Unknown, unaffected

Question 10

Square with DOT in it

Answer 10

male carrier

Question 11

square line through

Answer 11

male dead

Question 12

two lines between square and circle

Answer 12

Consanguineous ‘marriage’

Question 13

Consanguineous

Answer 13

relating to or denoting people descended from the same ancestor.

Question 14

Autosomal dominant

Autosomal recessive are caused by..

Answer 14

a gene on chromosomes 1 to 22

Question 15

x-linked recessive
x-linked dominant
y-linked are caused by

Answer 15

a gene on the sex chromosomes

Question 16

if a disease is recessive then…

Answer 16

an affected individual has USUALLY inherited the disease from both parents

Question 17

Characters of autosomal dominant disease..

Answer 17

• affecte person usually has at least one affected parent
• affects either sex
• transmitted by either sex
• child of an unaffected X affected mating as 50% chance of disease

Question 18

autosomal refers to…

Answer 18

disease from numbered chromosome (not sex chromosomes) no. 1-22

Question 19

Autosomal dominant diseases/phenotypes (humans)

Answer 19

• Achondroplasia - form of dwarfism
• polydactyly - extra fingers or toes
• Hairy mid-digit
• Widows peak

Question 20

Characteristics of autosomal recessive disorder

Answer 20

• affecteds usually have unaffected parents
• Parents are usually carriers
• Affects either sex
• increased incidence of inbreeding
• carriers and non-carriers are indistinguishable
• 2 carriers mate their offspring have a 1/4 chance of being affected

Question 21

Examples of autosomal recessive disorders

Answer 21

• Albinism
• Sickle cell anaemia
• Cystic fibrosis
• Attached ear lobes

Question 22

Cystic fibrosis median survival

Answer 22

31 years

Question 23

CF what doe sit affect?

Answer 23

Lungs, increased mucus secretion

Question 24

most common autosomal recessive disease in Europeans?

Answer 24

CF

Question 25

CF affecteds have..

Answer 25

two inactive copies of the CFTR gene

Question 26

CFTR…

Answer 26

Cystic Fibrosis Transmembrane conductance Regulator

Question 27

CF: the delta508 mutation results in

Answer 27

3bp deletion and a non-functional protein

Question 28

CF: heterozygotes may have (or had) a

Answer 28

selective advantage through resistant to cholera, typhoid or other diseases.

Question 29

Characteristics of x-linked recessive disorders

Answer 29

• affects mainly males
• probability of male offspring of female carrier being affected is 0.5
• females only affected if father affected and mother carrier.
• affected miles are usually born to be parents with no symptoms, although the mother often has affected male relatives

Question 30

examples of x-linked recessive disorders

Answer 30

• duchenne muscular dystrophy
• red-green colour blindness
• haemophilia

Question 31

Characteristics of x-linked dominant disorders

Answer 31

• affects either sex
• the child of an affected female has a 50% chance of being affected
• all female children of affected males are affected
• -no male children of accepted males are affected

Question 32

X-inactivation (lyonization)

Answer 32

females XX males XY. to compensate. In each cell of females one X is randomly inactivated. Occurs early in development and daughter cells have the same X inactivated.

Question 33

Characteristics of Y-linkage

Answer 33

Affects only males

All sons of an affected man are affected

Question 34

Examples of Y-linkage - very few

Answer 34

maleness

Hairy ear rims - possibly

Question 35

Mendelian disorders are usually..

Answer 35

rare - affected/carriers reduced fitness

Question 36

Mendel’s pea traits were

Answer 36

dominant