Lecture 9

Question 1

Autosomal recessive inheritance with complete penetrance will affect who?

Answer 1

25% of siblings, males and females equally affected. Typically on affected parent and no affected children of person affected

Question 2

Autosomal recessive yields which type of pedigree pattern?

Answer 2

horizontal pedigree pattern

Question 3

Examples of autosomal recessive inheritance

Answer 3

cystic fibrosis, albinism, sickle cell, phenylketonuria

Question 4

Most common genetic disorder in this country

Answer 4

Cystic Fibrosis

Question 5

Define cystic fibrosis

Answer 5

autosomal recessive disorder- males and females equally affected

Question 6

In someone with cystic fibrosis, where is the mutation>

Answer 6

located in chromosome 7- due to mutation in CFTR gene

Question 7

Most disease is highest incidence in Ireland?

Answer 7

Cystic Fibrosis

Question 8

What does cystic fibrosis affect?

Answer 8

affects chloride reabsorption, resulting in thick secretions- lungs and pancreas most affected, many are asymptomatic

Question 9

What will happen to newborns with cystic fibrosis?

Answer 9

Atelectasis- collapsed lung

Question 10

What happens in the GIT with cystic fibrosis?

Answer 10

meconium ileus, pancreatic enzyme deficiency leading to malabsorption, steatorrhea, bile obstruction– biliary cirrhosis

Question 11

What may occur just in men with cystic fibrosis?

Answer 11

infertility due to absence of vas deferens resulting in azoospermia

Question 12

Test done to screen for cystic fibrosis?

Answer 12

Sweat test- chloride level in sweats will be high

Question 13

What will will be seen on a patient’s fingers who has cystic fibrosis?

Answer 13

clubbing of fingers in chronic lung infection

Question 14

define albinism

Answer 14

a congenital disorder characterized by the complete or partial absence or defect of an enzyme involved in the production of melanin

Question 15

Two types of albinism

Answer 15

Oculo cutaneous albinism, ocular albinism

Question 16

Define Oculo cutaneous albinism

Answer 16

pigment lacking in eyes, skin and hear- autosomal recessive

Question 17

What can Oculo cutaneous albinism cause?

Answer 17

skin can burn easily, photophobia, nystagmus (rapid movement of eye), poor vision

Question 18

Define Ocular albinism

Answer 18

sex linked recessive disorder- only the eyes lack pigment- normal hair and skin color

Question 19

types of x linked inheritance

Answer 19

color blindness, duchene muscular dystrophy, fragile X syndrome

Question 20

Who does color blindness affect?

Answer 20

x linked recessive inheritance so it only affects males and females are carriers

Question 21

Who discovered color blindness?

Answer 21

John Dalton- atomic theory- he was colorblind

Question 22

what colors relate to color blindness

Answer 22

red/green

Question 23

Define Protonopia

Answer 23

red cones defective

Question 24

Define Deutonopia

Answer 24

green cones defective

Question 25

In what ethnicities is colorblindness common?

Answer 25

caucasians, asians, africans

Question 26

Difference between rods and cones

Answer 26

rods- night vision, cones- day vision

Question 27

Define Tritonopia

Answer 27

Blue/Yellow color blindness- defective gene on chromosome 7. not x linked!

Question 28

Causes of color blindness

Answer 28

vitamin A deficiency, brain injury, effects to medicine

Question 29

What is Duchenne Muscular Dystrophy?

Answer 29

a severe form of muscular dystrophy characterized by rapid progression of muscle degeneration, eventually leading to loss of ambulation and death- X linked recessive, females carriers

Question 30

At what age does Duchenne Muscular Dystrophy occur?

Answer 30

age 5- by age 10 braces may be required for walking, wheelchair dependent by age 12, life expectancy is around 20

Question 31

What will the calves of someone with Duchennes look like?

Answer 31

pseudo hypertrophy of calf muscles

Question 32

Organizations specific to DMD?

Answer 32

The foundation to eradicate Duchenne, The shakti Foundation, Famous sufferers of DMD- who design engine for Flat Deno Car

Question 33

Fragile X is due to mutation where?

Answer 33

mutation of FMR1 gene on the X chromosome- gene contains 200 repeats of the CGG codon

Question 34

Do we know if Fragile X syndrome is recessive or dominant?

Answer 34

NO- carrier mother has some symptoms as well - inheritance pattern resembles recessive

Question 35

WHen will carrier women of fragile X go through menopause?

Answer 35

before the age of 40- premature menopause

Question 36

Clinical features of someone with fragile X

Answer 36

high forehead, large ears, prominent jaw, males have large testes, connective tissue weakness, hyper extensible joints, learning difficulties, speech issues

Question 37

The most frequently diagnosed autosomal recessive disorders are...

Answer 37

cystic fibrosis, betathalassemia, and sickle cell disease

Question 38

THe most common dominant diseases....

Answer 38

myotonic dystrophy, huntington's disease