5 - Genetic Disorders Flashcards Preview

Chapters 1-9 - Robbins Pathologic Basis of Disease, 9th Edition > 5 - Genetic Disorders > Flashcards

Flashcards in 5 - Genetic Disorders Deck (93)
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1

What is the lifetime frequency of genetic disorders?

670 per 1000

2

What are the three broad categories of genetic disorders?

Single gene mutations with large effects; chromosomal disorders; complex multigenic disorders (most common)

3

Multiple variations of the same gene is referred to as:

Polymorphisms

4

Describe Mendelian disorders.

Disorders passed on by mutations that affect single genes and have large effects

5

What are the major types of point mutation?

Silent, missense, and nonsense

6

What are the two types of missense mutation?

Conservative (similar amino acid replacement) and nonconservative (very different amino acid replacement)

7

What kind of effects can deletions within introns have?

Promoters, enhancers, splicing junctions, and other regulatory genes can be altered (often decreasing gene expression)

8

In what situation are deletions or insertions of DNA not going to result in a frameshift mutation?

If the deletion or insertion is a multiple of three nucleotides

9

What are some examples of disorders associated with trinucleotide-repeat mutations? Which trinucleotides are involved in each disorder?

Fragile X syndrome (CGG), Huntington's disease (CAG), myotonic dystrophy (CTG), Friedrich's ataxia (GAA)

10

What disorder types don't fit neatly into the three main types (chromosomal abnormalities, single gene mutations, and multigenic disease)?

Trinucleotide-repeats, mitochondrial inheritance, imprinting, mosaicism

11

When do sickle cell heterozygotes manifest red blood cell sickling?

Only after unusual circumstances like lowered oxygen tension

12

A single mutant gene may lead to many end effects. What is this called?

Pleiotropism

13

What is it called when mutations at several genetic loci may produce the same trait?

Genetic heterogeneity

14

What are some forms by which single-gene mutations are transmitted (3)?

Autosomal dominant, autosomal recessive, and X-linked

15

Do any patients with autosomal dominant disorders not have affected parents?

Yes, these patients are the result of new mutations (seem to occur in the germ cells of relatively old fathers)

16

Do autosomal dominant diseases display variation in penetrance and expressivity?

Yes

17

Which protein genes are more likely to be affected in autosomal dominant disorders?

Key structural proteins; metabolic pathway-regulating feedback inhibitors

18

Which is more common, loss-of-function or gain-of-function mutations?

Loss-of-function

19

What genetic disorder category is the largest of the Mendelian disorders?

Autosomal recessive disorders

20

What percentage of sex-linked disorders are X-linked? How many of these are recessive?

All; most

21

What inheritance pattern does Marfan syndrome show?

Autosomal dominant

22

What extracellular glycoprotein is deficient in Marfan syndrome?

Fibrillan-1

23

Lack of fibrillan-1 causes what general effects in Marfan syndrome?

Lack of tropoelastin scaffolding; excessive TGF-beta activation

24

What are the main abnormalities in Marfan syndrome?

Skeletal abnormalities, subluxation or dislocation of the lens, mitral valve prolapse, and ascending aortic dilation

25

What is the main course of treatment for Marfan syndrome?

Beta-blockers (reduce heart rate and aortic wall stress)

26

What group of disorders is characterized by defects in the synthesis or structure of fibrillar collagen?

Ehlers-Danlos Syndromes (VI) (also, osteogenesis imperfect and Alport syndrome)

27

Which Ehlers-Dalos subtypes are autosomal recessive?

Kyphoscoliosis; dermatosparaxis

28

Describe vascular Ehlers-Danlos Syndrome.

Thin skin, arterial or uterine rupture, bruising, small joint hyper extensibility; autosomal dominant

29

Describe classic Ehlers-Danlos Syndrome.

Skin and joint hypermobility, atrophic scars, easy bruising; autosomal dominant

30

What is familial hypercholesterolemia?

An autosomal dominant disease in which LDL receptors are under expressed