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