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33 Cards in this Set

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  • Back
Most single gene mutations are ____ (some are new).
Familial
How many mendelian single-gene disorders are known?
More than 5000
What is a mutation?
Any permanent change to DNA
What types of things cause mutations?
radiation, chemicals, viruses, normal metabolism.
Describe the qualities of an autosomal dominant disorder.
-predictable inheritance pattern
- affects males and females equally.
- unaffected don't transmit
Two main patterns of transmission ____.
Two main patterns of expression _____/
1. autosomal, sex-linked
2. dominant, recessive.
In an autosomal dominant disorder, usually offsppring have a ___% chance of expressing. In a heterozygous mating, it goes to ___%
1. 50
2. 75
What is Marfan Syndrome?
- autosomal dominant.
- tall, slender, long appendages
- arachnodactyly
- risk of lesions to aorta and valves.
- has Gibrillin I on chromosome 15
Describe Huntington disease.
- autosomal dominant
- mental deterioration
- involuntary appendage movement
- caused by abnormal CAG repeats on csome 4
Describe characteristics of an autosomal recessive disorder.
- Affects genders equally
- disease not apparent in parents of affected
- unaffected "carriers" may transmit
- heterozygote mating = 25% chance with 50% likelihood of carrier
Describe the characteristics of albinism.
- 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.
Describe the characteristics of phenylketonuria.
- 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.
Describe the characteristics of cystic fibrosis.
- 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.
What is the most common single-gene disorder in caucasians?
Cystic fibrosis.
Describe the characteristics of a sex-linked disorder.
- mutation of sex chromosome.
- almost exclusively X-linked
- females rarely express, often carriers,
- males if they have the gene they express it
Describe Hemophilia A
- sex-linked disorder
- lack of gene that codes for factor VIII
- causes profuse bleeding
- traced back to royal families of Europe (Queen Victoria)
Describe characteristics of Fragile X syndrome.
- sex-linked disorder
- Triplet repeat mutation
- results in mental retardation
- seen as constriction on long arm of X c'some
Describe characteristics of mitochondrial gene mutations.
- 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)
What is genomic imprinting?
maternal and paternal chromosomes are different and mutations of them have different affects.
Prader-Willi syndrome and Angelman Syndrom are an example of the importance of what?
Genomic imprinting.
Prader - Willi syndrome is?
- deletion on paternal version of chromosome 15
- mental retardation, short stature, obesity, poor muscle tone, hypogonadism
Angelman Sydrome is??
- deletion on maternal version of chromosome 15
-mental retardation, ataxia, inappropriate laugh.
Describe the characteristics of a Polygenic mutation.
- 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
Describe digenic retinitis pigmentosa.
- example of multigenic trait
- causes retinal degeneration by retinitis pigmentosa
- two mutation sin two different unlinked genes... both required to manifest disease
Describe the genetic characteristics of a venous thrombosis
gene interaction with environmental influence that causes coagulation in vein
- may be influenced by birth control pills, smoking, age, etc
Describe the characteristics of Hirschsprung Disease (HSCR)
- abnormality of parasympathetic innervation of the gut (no peristalsis)
- usually isolated to 1 segment
- high risk ration for siblings.
Hirschsprung Disease has what inheritance pattern
- 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
Describe genetic characteristics of type I Diabetes mellitus
- 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
Describe the genetic characteristics of alzheimer disease
- 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.
What is the most common cause of dementia in the elderly?
Alzheimer disease
How many alleles are thought to be associated with Alzheimer disease?
3
What gene is associated with Alzheimer? What chromosome is it on?
1. APOE
2. 19
Type I diabetes is caused by mutations of which HLA genes?
HLA-DQ3, HLA-DQ4