Genetics: Single Gene Disorders And Complex Inheritance

Front 1

Most single gene mutations are ____ (some are new).

Back 1

Familial

Front 2

How many mendelian single-gene disorders are known?

Back 2

More than 5000

Front 3

What is a mutation?

Back 3

Any permanent change to DNA

Front 4

What types of things cause mutations?

Back 4

radiation, chemicals, viruses, normal metabolism.

Front 5

Describe the qualities of an autosomal dominant disorder.

Back 5

-predictable inheritance pattern
- affects males and females equally.
- unaffected don't transmit

Front 6

Two main patterns of transmission ____.
Two main patterns of expression _____/

Back 6

1. autosomal, sex-linked
2. dominant, recessive.

Front 7

In an autosomal dominant disorder, usually offsppring have a ___% chance of expressing. In a heterozygous mating, it goes to ___%

Back 7

1. 50
2. 75

Front 8

What is Marfan Syndrome?

Back 8

- autosomal dominant.
- tall, slender, long appendages
- arachnodactyly
- risk of lesions to aorta and valves.
- has Gibrillin I on chromosome 15

Front 9

Describe Huntington disease.

Back 9

- autosomal dominant
- mental deterioration
- involuntary appendage movement
- caused by abnormal CAG repeats on csome 4

Front 10

Describe characteristics of an autosomal recessive disorder.

Back 10

- Affects genders equally
- disease not apparent in parents of affected
- unaffected "carriers" may transmit
- heterozygote mating = 25% chance with 50% likelihood of carrier

Front 11

Describe the characteristics of albinism.

Back 11

- autosomal recessive disorder
- lack of hair, skin, and eye pigment
- six forms, one has lack of tyrosinase
- high risk of sunburn, skin CA, impaired vision, etc.

Front 12

Describe the characteristics of phenylketonuria.

Back 12

- autosomal recessive disorder
- inborn error of metabolism results in inability to metabolize phenylalanine
- irritable, tremorous, and slowly develop retardation
- urine with musty odor
- managed by low-phenylalanine diet.

Front 13

Describe the characteristics of cystic fibrosis.

Back 13

- autosomal recessive disorder.
- defective chloride ion membrane transporter
- results in abnormally thick mucous in lung and pancreas
- results from mutation onf a gene on csome 7.

Front 14

What is the most common single-gene disorder in caucasians?

Back 14

Cystic fibrosis.

Front 15

Describe the characteristics of a sex-linked disorder.

Back 15

- mutation of sex chromosome.
- almost exclusively X-linked
- females rarely express, often carriers,
- males if they have the gene they express it

Front 16

Describe Hemophilia A

Back 16

- sex-linked disorder
- lack of gene that codes for factor VIII
- causes profuse bleeding
- traced back to royal families of Europe (Queen Victoria)

Front 17

Describe characteristics of Fragile X syndrome.

Back 17

- sex-linked disorder
- Triplet repeat mutation
- results in mental retardation
- seen as constriction on long arm of X c'some

Front 18

Describe characteristics of mitochondrial gene mutations.

Back 18

- passed during cell division
- code for oxidative respiration enzymes
- dysfunction in tissues with high ATP needs (lack of enzymes = lack of ATP production)
- inheritance pattern tricky(always come from mother)

Front 19

What is genomic imprinting?

Back 19

maternal and paternal chromosomes are different and mutations of them have different affects.

Front 20

Prader-Willi syndrome and Angelman Syndrom are an example of the importance of what?

Back 20

Genomic imprinting.

Front 21

Prader - Willi syndrome is?

Back 21

- deletion on paternal version of chromosome 15
- mental retardation, short stature, obesity, poor muscle tone, hypogonadism

Front 22

Angelman Sydrome is??

Back 22

- deletion on maternal version of chromosome 15
-mental retardation, ataxia, inappropriate laugh.

Front 23

Describe the characteristics of a Polygenic mutation.

Back 23

- two or more mutant genes act together
-no clear mode of inherittance
- influenced by environment
- very common
- include HTN, CA, DM, cleft lip, heart defects

Front 24

Describe digenic retinitis pigmentosa.

Back 24

- example of multigenic trait
- causes retinal degeneration by retinitis pigmentosa
- two mutation sin two different unlinked genes... both required to manifest disease

Front 25

Describe the genetic characteristics of a venous thrombosis

Back 25

gene interaction with environmental influence that causes coagulation in vein
- may be influenced by birth control pills, smoking, age, etc

Front 26

Describe the characteristics of Hirschsprung Disease (HSCR)

Back 26

- abnormality of parasympathetic innervation of the gut (no peristalsis)
- usually isolated to 1 segment
- high risk ration for siblings.

Front 27

Hirschsprung Disease has what inheritance pattern

Back 27

- occurs through multiple generations and multiple siblings
- may be autosomal dominant or recessive (not really known)
- males 2x more likely (sex-linked??)
- likely caused by mutations in many different and unlinked genes

Front 28

Describe genetic characteristics of type I Diabetes mellitus

Back 28

- manifests in childhood or adolescence
- autoimmune destruction of B-cells in pancreatic islets result in no insulin production
- MHC locus may be major genetic factor, other genes likely involved
- also influenced by genetic factor

Front 29

Describe the genetic characteristics of alzheimer disease

Back 29

- fatal neurodegenerative disease
- chronic, progressive loss of memory and intellectual function
- risks include age, gender, fam hx.
- only dx post-mortem
- results in destruction of cortcal tissue due to AB peptide plaques derived from cleavage of nml protein.

Front 30

What is the most common cause of dementia in the elderly?

Back 30

Alzheimer disease

Front 31

How many alleles are thought to be associated with Alzheimer disease?

Back 31

3

Front 32

What gene is associated with Alzheimer? What chromosome is it on?

Back 32

1. APOE
2. 19

Front 33

Type I diabetes is caused by mutations of which HLA genes?

Back 33

HLA-DQ3, HLA-DQ4