mendelian disorders and multifactorial disease

Question 1

PKU and CF

Answer 1

Autosomal recessive

Question 2

2 X-linked conditions

Answer 2

DMD, Hemoph A

Question 3

Autosomal dominant condition

Answer 3

Familial hypercholest

Question 4

Males and females pass on the trait, MALE TO MALE transmission CAN occur

Answer 4

Autosomal dominant

Question 5

Disease in AD condition is due to

Answer 5

1. haploinsufficiency
2. Dominant negative effect
3. Mutation enhances protein function
4. loss of the normal copy can happen

Question 6

Proportion of individuals with a mutation causing a particular disorder who exhibit clinical symptoms

Answer 6

Penetrance - ALL OR NOTHING

Question 7

Penetrance may be explained by

Answer 7

Modifier genes

Question 8

Variable expressivity is

Answer 8

different DEGREES of severity or manifestations of a disease in different individuals who have mutations int he same gene
e.g.

Question 9

Variable expressivity can be explained by

Answer 9

differences due to genotype/phenotype effects
presence of modifier genes
environmental factors

Question 10

Example of AD disorder with variable expressivity

Answer 10

Lynch syndrome (with uterine cancer)
PCKD
Marfan syndrome
FAP 100% penetrant 
Hereditary breast/ov ca

Question 11

2 yr old recurrent resp infection with Pseudo Aerugonisoa

Answer 11

autosomal recessive CF

Question 12

CF predominantly

Answer 12

Northern european 1/2500

NOT usually in multiple generations

Question 13

important AR conditions

Answer 13

• sickle cell anemia
• Most inborne errors of metabolism - PKU etc.
• Thalessmia

Question 14

6 yr old with progressive weakness, early death due to resp failure in Fam Hx, enlarged calf muscles

Answer 14

DMD
elevated CK levels 50x normal
mutation in dystrophin

Question 15

one third of DMD cases are thought to be the result of

2/3 of DMD cases

Answer 15

new mutations

have carrier mothers

Question 16

Carrier mothers of DMD have mutations that are

Answer 16

germline in all cells
blood test positive
each son with 50% risk and 50% chance of carriers in females

Question 17

if DMD mother has germline mosaicism

Answer 17

she will have a mutation in SOME of her egg cells
blood tests will NOT show a mutation
can have more than 1 affected son

Question 18

No male to male transmissionin

Answer 18

X-linked inheritance

Question 19

1/3 of Hemophilia A patients have

Answer 19

a new mutation

2/3 carriers

Question 20

Multifactorial diseases are different from single gene disorders how?

Answer 20

1- lower heritability

2- no single factor responsible for disease

Question 21

AD disorders

AR disorders: CF, sickle cell

Answer 21

Familial hypercholesteremia

Achondroplasia