Genetics Of Respiratory Diseases

Front 1

what are the 3 features of cystic fibrosis?

Back 1

most common fatal genetic disease!

1) buildup of thick, sticky mucus in lungs
2) pancreatic insufficiency
3) abnormally salty sweat

Front 2

What is the cause of CF? (2)

Back 2

mutated single gene (the Cystic fibrosis gene) on chromosome 7.
transcribes CFTR (cystic fibrosis transmembrane conductance regulator protein)

Front 3

What is the function of CFTR? (cystic fibrosis transmembrane conductance regulator protein?) (1)

Back 3

sits in membrane of certain cells, controls passage of chloride ions in and out of the cell

Front 4

What happens to CFTR in people with CF? (2)

Back 4

1) 70-80% cases
CFTR is completely missing from the membrane

2) Gene is mutated so the CFTR doesn't work.
It doesn't open. Chloride ions can't pass through the membrane

Front 5

What happens to the CF gene in people with CF?

メ What is the name of this mutation? メ

Back 5

3 letters of code are missing.
No phenylalanine in position 508

メ Delta-F508 メ

Front 6

What is the effect of a missing/malfunctioning CFTR on the guy's sweat?

b) Compare it to a normal person's sweat. (2)

Back 6

Saltier sweat than normal

b)
1) sweat producting starts in tangled end of gland, where cells secrete water into gland's duct.
2) when sweat rises, cells lining upper duct reabsorb sodium and chloride ions and molecules in sweat. There is no reabsorption in people with CF.

Front 7

Compare normal pancreas with CF pancreas.

Back 7

Normal pancreas: chloride-pumping actions of of CFTR cause water to follow chloride into the duct, where the watery slurry flows out of the duct and into the intestine carrying the enzymes.

CF pancreas: chloride and water stay in the cells, so there's no slurry to carry the enzymes away, so enzymes digest the pancreas itself. This leads to inflammation, thick mucus plugging the ducts.

Front 8

Describe the CF lung.

Back 8

mucus in the lung becomes very thick.
lung becomes prone to bacterial infection because the mucus can support bacterial growth

Front 9

Genetics of CF (2)

Back 9

1) single gene defect
2) autosomal recessive

Front 10

What is the probability of having a CF child?

Back 10

1/4
if both parents are carriers

Front 11

What are the population genetics of CF?

Back 11

5% white Americans asymptomatic carriers
1/2500 of children of European descent have
1000 new cases a year
30, 000 people living with the disorder

Most patients are White, then Hispanic, then Black, then Asian.

Front 12

How can you diagnose CF?

Back 12

molecular diagnosis for CF gene delta F508

Front 13

Describe Asthma (3)

Back 13

1) muscle in airway wall squeezes the airway narrower
2) wall of airway swells, further narrowing the air passage
3) inside lining of airway produces mucus, further blocking the air passage

Front 14

What is the relation between asthmatic parents and children?

b) How so? (2)

Back 14

an affected parent is more likely to produce an affected child

b) more severely affected and;
2 affected parents are more likely to produce an affected child

Front 15

What are the hallmarks of multifactorial disease like asthma? (2)

Back 15

continuous/quantitative
regression to mediocrity

Front 16

Give examples of regression to mediocrity (6)

Back 16

1. intelligence
2. height
3. asthma
4. hypertension
5. diabetes mellitus
6. cleft lip, cleft palate

Front 17

What is the hypothesis for nonmendelian trait/disease-polygenic?

Back 17

Polygenic: involves many loci, each individual locus having only a small effect

1. multiple genes, each with relatively small effect on the phenotype
2. these traits or diseases reflect cumulative effect of genetic variation at these loci (genes)
3. these multiple genes also have interplay with environmental factors (factors outside the human body)

Front 18

How do you decide if a disease is influenced by genetics?

Back 18

adopted vs. natural children:
~find adopted people suffering from disease known to run in families and ask if it runs in their biological or adoptive family.
~does being adopted away form the family save a child from the risk of the disease.

Front 19

What is familial tendency?

Back 19

higher frequency of specific disease among relatives of affected individuals.

Front 20

b) what must we remember about families concerning prevalence of specific disease?

Back 20

you are closer to your family in terms of genes, but you also share common environments

Front 21

what is twin study? (3)

Back 21

1) monozygotic twins: same genome, different environmental factors
2) dizygotic wins: only half their genes in common, different environmental factors.

3)MZ twins separated at birth. but this is a rare event

Front 22

What is concordance? (for genetic factors in common diseases and malformation)

Back 22

concordance rate = both affected
------------------ x100
(one affected + both affected)

concordance rate is inheritance by 2 related individuals of same genetic characteristic e.g. susceptibility to disease

Front 23

What genes are involved in asthma?

b) give some examples (4)

Back 23

No single asthma gene: it is combined effects of several weak genes that add up to produce susceptibility to asthma

b)
1. beta-2-adrenergic on chromosome 5
2. interleukin genes on chromosome 5
3. HLA class II on short arm of chromosome 6
4. TNF-alpha on chromosome 6

Front 24

What environmental factors are involved in asthma? (3)

Back 24

1. air quality (tobacco smoke, pollution, chemical fumes, dust mites, temperature, humidity)

2. amount of salt in diet (more salt, more asthma)

3. lung infection

Front 25

debate genetic vs environmental

Back 25

the susceptibility to the disease is genetically determined.
environmental triggers must be present to bring about the diseases.
development of polygenic disease is determined by interplay between genes and environment