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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
Q

Give some examples of X-linked diseases.

A

Hemophilia A and B

Hunter syndrome

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26
Q

Inactivation of an abnormally high percentage of normal X chromosomes leading to clinical evidence of a recessive disease in a heterozygous female

A

unfavorable lyonization

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27
Q

T/F

Lyonization occurs in all females.

A

True

Unfavorable lyonization, however, can happen in some

28
Q

While almost all X-linked disorders are recessive, a few are dominant. Name one.

A

oral-facial-digital syndrome (OFD) type I

29
Q

Name the diseases caused by mutations in structural proteins.

A

Marfan syndrome

Ehlers-Danlos syndromes (about 6 different types)

30
Q

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).

A

Marfan Syndrome

31
Q

Name the clinical signs/symptoms and possible complications of Marfan syndrome.

A
  • 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
Q

These syndromes pose problems for collagen synthesis.

A

Ehlers-Danlos Syndromes

33
Q

Name the signs/symptoms and possible complications of Ehlers-Danlos syndromes.

A
  • hyperextensible skin and hypermobile joints
  • skin fragility and delayed wound healing
  • rupture of colon, large arteries
  • hernias
34
Q

Name the diseases caused by mutations in receptor proteins.

A 
Familial hypercholesterolemia
Cystic Fibrosis (chloride channel protein)
35
Q

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.

A

Familial hypercholesterolemia

36
Q

Familial hypercholesterolemia can cause ________ of the skin and premature _________.

A

xanthomas

atherosclerosis

37
Q

Understanding the role of the LDL receptors has led to the design of the ______ family of drugs used to control cholesterol levels.

A

statin

38
Q

Name the diseases caused by mutations in genes encoding enzyme proteins.

A
  • Phenylketonuria
  • Galactosemia
  • Lysosomal storage diseases (Tay-Sachs disease, Niemann-Pick disease, Gaucher disease, mucopolysaccharidoses, Hurler disease)
  • Hunter syndrome
39
Q

Give some examples of autosomal recessive disorders.

A

Phenylketonuria
Lysosomal storage diseases (Tay-Sachs disease, Niemann-Pick disease, Gaucher disease, mucopolysaccharidoses, Hurler disease)

40
Q

This disorder affects 1 in 10,000 caucasian infants and can lead to hyperphenylalaninemia due to a severe lack of phenylalanine hydroxylase.

A

Phenylketonuria

41
Q

Infants affected by phenylketonuria are normal at birth, but elevated _________ levels impair ______ development and mental retardation is evident by __ of age.

A

phenylalanine
brain
6 months

42
Q

These diseases often affect infants and young children and are caused by an accumulation of insoluble large molecules (sphingolipids and mucopolysaccharides) in macrophages.

A

Lysosomal storage diseases

43
Q

Give examples of lysosomal storage diseases.

A 
Tay-Sachs disease
Niemann-Pick disease
Gaucher disease
Mucopolysaccharidoses
Hurler disease (MPS type I)
Hunter disease
44
Q

This disease is caused by a deficiency of alpha-L-iduronidase (laronidase) and the life expectancy is 6-10 years if left untreated.

A

Hurler disease (MPS type I)

Note: bone marrow transplant or enzyme replacement ($$) may improve outlook.

45
Q

This syndrome is x-linked, similar to Hurler disease, and involves a deficiency of L-iduronate sulfatase

A

Hunter disease

46
Q

Patients affected by this condition have coarse facial features, clouding of corneas, joint stiffness, and mental retardation.

A

Mucopolysaccharidoses

47
Q
  • 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.
A

Multifactorial (polygenic) disorders

48
Q

Name the cytogenic disorder that involves autosomes.

A

Trisomy 21 (Down syndrome)

49
Q

Name cytogenic disorders that involve sex chromosomes.

A

Klinefelter syndrome

Turner syndrome

50
Q

It is estimated that 1 in ___ newborns have a chromosomal abnormality

A

200

51
Q

Of all 1st trimester spontaneous abortions, what percentage of fetuses had a chromosomal abnormality?

A

50%

52
Q
  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 (_______).
A
  1. polyploidy
  2. aneuploidy
    trisomy
    monosomy
53
Q

________ abnormalities usually result from chromosome breakage followed by loss or rearrangement of material.

A

Structural

54
Q

Transfer of a part of one chromosome to another non-homologous chromosome

A

translocation

55
Q

When fragments are exchanged between two chromosomes it’s termed…

A

reciprocal translocation

56
Q

Loss of a portion of a chromosome

A

deletion

57
Q

When a chromosome breaks in two points, then the released fragment is reunited after a complete turnaround

A

inversion

58
Q

This is the most common of the chromosomal disorders and is associated with advanced maternal age (1:25 if mother over age of 45).

A

Trisomy 21 (Down syndrome)

59
Q

Name clinical signs and possible complications of Trisomy 21.

A
  • 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
Q

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).

A

Klinefelter syndrome

61
Q

Name the clinical signs of Klinefelter syndrome.

A
  • increased length of lower limbs
  • reduced body hair
  • gynecomastia
  • hypogonadism
  • increased frequency of taurodontism
62
Q

This syndrome is due to a partial or complete absence of one of the X chromosomes (female hypogonadism).

A

Turner syndrome

63
Q

Name the clinical signs of Turner syndrome.

A
  • 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
Q

Name 3 methods used to diagnose genetic diseases.

A
  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
Q

Name some indications for PRENATAL genetic analysis.

A
  • 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
Q

Name some indications for POSTNATAL genetic analysis.

A
  • 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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