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General Pathology > Genetic Diseases > Flashcards

Genetic Diseases Flashcards

1
Q

Define heterozygous.

A

Only one chromosome in a pair at a given gene locus is affected

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2
Q

Define homozygous.

A

Both chromosomes at a given gene locus are affected

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3
Q

Define mutation (in general).

A

A permanent change in DNA

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4
Q

If the mutation affects the germ cell…

A

it will affect progeny

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5
Q

If the mutation affects somatic cells…

A

it may cause tumors or developmental malformations

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6
Q

Name the 3 types of mutations.

A

Point (missense) mutation
Frameshift mutation
Trinucleotide repeat mutation

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7
Q

In a point (missense) mutation…

Give an example of a disease/condition resulting from a point mutation.

A

a single nucleotide base is substituted

example: sickle cell anemia

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8
Q

In a frameshift mutation…

A

1 or 2 base pairs are inserted or deleted - this alters the reading frame of the DNA strand

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9
Q

In a trinucleotide repeat mutation…

Give an example of a disease/condition resulting from a trinucleotide repeat mutation.

A

there is amplification of a sequence of 3 nucleotides

example: Fragile X syndrome

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10
Q

Name the other factors impacting protein-coding gene function.

A

polymorphism
epigenetic changes
alterations in non-coding RNAs

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11
Q

Mendelian disorders are diseases caused by…

A

single-gene defects

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12
Q

What are the different transmission patterns of Mendelian disorders?

A

autosomal dominant
autosomal recessive
X-linked (almost all are recessive)

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13
Q

All of the following characteristics describe which Mendelian transmission pattern?

  • mutated gene on one of the autosomes
  • heterozygous (only one parent affected)
  • outward physical changes, many with delayed onset
  • half of offspring will have disease if only one parent affected
A

autosomal dominant

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14
Q

Individual has mutated gene, but doesn’t or partially expresses it phenotypically

A

reduced or incomplete penetrance

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15
Q

The trait is expressed differently among affected individuals who have the same mutant gene

A

variable expressivity

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16
Q

Affected individuals may not have affected parents because the disease arose from a new mutation

A

de novo mutation

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17
Q

Give some examples of autosomal dominant disorders.

A 
Huntington's Disease
Neurofibromatosis
Marfan Syndrome
Familial hypercholesterolemia
von Willebrand Disease
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18
Q

Name this disorder:

  • Causes tumors to form on nerve tissue
  • Nearly 100% penetrance
  • Nearly everyone who has this mutation will show evidence
  • Affects 1 in every 3,000 live births
  • Highly variable expressivity
A

Neurofibromatosis

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19
Q

All of the following characteristics describe which Mendelian transmission pattern?

  • Largest group of Mendelian disorders
  • Affected parents are homozygous (parents usually appear unaffected)
  • 25% of offspring affected, 50% carriers (heterozygous)
  • may be result of consanguinity
  • many disorders present with enzyme defects that produce inborn errors of metabolism
  • age of onset typically early in life
A

autosomal recessive

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20
Q

All sex-linked diseases are…

A

X-linked

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21
Q

Almost all x-linked diseases are dominant or recessive?

A

recessive

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22
Q

Females are usually ______ because they have 2 X chromosomes .

A

carriers

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23
Q

T/F

Females cannot be affected by X-linked disorders because they have 2 X chromosomes and can only be carriers.

A

False

Females can inherit 2 mutated copies (homozygous) and will be affected

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24
Q

One trait may be linked to the Y chromosome. Name that trait.

A

hairy ears

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25
Give some examples of X-linked diseases.
Hemophilia A and B | Hunter syndrome
26
Inactivation of an abnormally high percentage of normal X chromosomes leading to clinical evidence of a recessive disease in a heterozygous female
unfavorable lyonization
27
T/F | Lyonization occurs in all females.
True | Unfavorable lyonization, however, can happen in some
28
While almost all X-linked disorders are recessive, a few are dominant. Name one.
oral-facial-digital syndrome (OFD) type I
29
Name the diseases caused by mutations in structural proteins.
Marfan syndrome | Ehlers-Danlos syndromes (about 6 different types)
30
This connective tissue disorder is due to a mutation of the FBN1 gene resulting in abnormal fibrillin (a glycoprotein necessary for normal elastic fiber production).
Marfan Syndrome
31
Name the clinical signs/symptoms and possible complications of Marfan syndrome.
- tall, thin body habitus with abnormally long legs, arms, and fingers (arachnodactyly - "spider fingers") - dislocation of lens of eye - aortic aneurysm/dissection leading to heart failure and aortic rupture
32
These syndromes pose problems for collagen synthesis.
Ehlers-Danlos Syndromes
33
Name the signs/symptoms and possible complications of Ehlers-Danlos syndromes.
- hyperextensible skin and hypermobile joints - skin fragility and delayed wound healing - rupture of colon, large arteries - hernias
34
Name the diseases caused by mutations in receptor proteins.
``` Familial hypercholesterolemia Cystic Fibrosis (chloride channel protein) ```
35
This disease is caused by a mutation in the gene for the LDL receptor and results in impaired metabolism and increased LDL cholesterol in the plasma.
Familial hypercholesterolemia
36
Familial hypercholesterolemia can cause ________ of the skin and premature _________.
xanthomas | atherosclerosis
37
Understanding the role of the LDL receptors has led to the design of the ______ family of drugs used to control cholesterol levels.
statin
38
Name the diseases caused by mutations in genes encoding enzyme proteins.
- Phenylketonuria - Galactosemia - Lysosomal storage diseases (Tay-Sachs disease, Niemann-Pick disease, Gaucher disease, mucopolysaccharidoses, Hurler disease) - Hunter syndrome
39
Give some examples of autosomal recessive disorders.
Phenylketonuria Lysosomal storage diseases (Tay-Sachs disease, Niemann-Pick disease, Gaucher disease, mucopolysaccharidoses, Hurler disease)
40
This disorder affects 1 in 10,000 caucasian infants and can lead to hyperphenylalaninemia due to a severe lack of phenylalanine hydroxylase.
Phenylketonuria
41
Infants affected by phenylketonuria are normal at birth, but elevated _________ levels impair ______ development and mental retardation is evident by __ of age.
phenylalanine brain 6 months
42
These diseases often affect infants and young children and are caused by an accumulation of insoluble large molecules (sphingolipids and mucopolysaccharides) in macrophages.
Lysosomal storage diseases
43
Give examples of lysosomal storage diseases.
``` Tay-Sachs disease Niemann-Pick disease Gaucher disease Mucopolysaccharidoses Hurler disease (MPS type I) Hunter disease ```
44
This disease is caused by a deficiency of alpha-L-iduronidase (laronidase) and the life expectancy is 6-10 years if left untreated.
Hurler disease (MPS type I) Note: bone marrow transplant or enzyme replacement ($$) may improve outlook.
45
This syndrome is x-linked, similar to Hurler disease, and involves a deficiency of L-iduronate sulfatase
Hunter disease
46
Patients affected by this condition have coarse facial features, clouding of corneas, joint stiffness, and mental retardation.
Mucopolysaccharidoses
47
- Two or more genes responsible, plus environmental (non genetic) influences - Governs many physiologic traits (height, weight, BP, hair color) - May underlie common diseases such as DM, HTN, gout, schizophrenia, bipolar, etc.
Multifactorial (polygenic) disorders
48
Name the cytogenic disorder that involves autosomes.
Trisomy 21 (Down syndrome)
49
Name cytogenic disorders that involve sex chromosomes.
Klinefelter syndrome | Turner syndrome
50
It is estimated that 1 in ___ newborns have a chromosomal abnormality
200
51
Of all 1st trimester spontaneous abortions, what percentage of fetuses had a chromosomal abnormality?
50%
52
1. An increased chromosome count that is a multiple of that normally seen is _______ and generally results in spontaneous abortion. 2. Any number that is not an exact multiple of the normal chromosome count is termed _______ and examples include an extra chromosome (______) and absence of a chromosome (_______).
1. polyploidy 2. aneuploidy trisomy monosomy
53
________ abnormalities usually result from chromosome breakage followed by loss or rearrangement of material.
Structural
54
Transfer of a part of one chromosome to another non-homologous chromosome
translocation
55
When fragments are exchanged between two chromosomes it's termed...
reciprocal translocation
56
Loss of a portion of a chromosome
deletion
57
When a chromosome breaks in two points, then the released fragment is reunited after a complete turnaround
inversion
58
This is the most common of the chromosomal disorders and is associated with advanced maternal age (1:25 if mother over age of 45).
Trisomy 21 (Down syndrome)
59
Name clinical signs and possible complications of Trisomy 21.
- mental retardation - epicanthic folds - flat facial profile - cardiac malformations - increased susceptibility to infection (severe periodontal disease in childhood) - large tongue - increased prevalence of acute leukemia
60
This syndrome is define as male hypogonadism that develops when there are at least two X chromosomes and one or more Y chromosomes (most are 47, XXY).
Klinefelter syndrome
61
Name the clinical signs of Klinefelter syndrome.
- increased length of lower limbs - reduced body hair - gynecomastia - hypogonadism - increased frequency of taurodontism
62
This syndrome is due to a partial or complete absence of one of the X chromosomes (female hypogonadism).
Turner syndrome
63
Name the clinical signs of Turner syndrome.
- markedly short stature - webbing of the neck - low posterior hairline - shield-like chest - high-arched palate - variety of congenital cardiac malformations - failure to develop secondary sex characteristics - primary amenorrhea
64
Name 3 methods used to diagnose genetic diseases.
1. Fluorescence in situ Hybridization (FISH) 2. Comparative Genomic Hybridization 3. Molecular diagnosis (PCR analysis, compare order of nucleotides, restriction enzymes, add fluorescently labeled nucleotides)
65
Name some indications for PRENATAL genetic analysis.
- mother's age >34 - parent who is a carrier of a chromosomal translocation - Hx of a previous child with chromosomal abnormality - parent who is a carrier of an X-linked disorder
66
Name some indications for POSTNATAL genetic analysis.
- multiple congenital abnormalities - unexplained mental retardation/developmental delay - suspected aneuploidy (i.e. Down syndrome) - suspected sex chromosomal abnormality - infertility - multiple spontaneous abortions

General Pathology (9 decks)

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