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gen-path 2 > Genetic diseases > Flashcards

Genetic diseases Flashcards

1
Q

Mutations of a certain gene _____ may affect one or both of the chromosomes in a pair

A

locus

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2
Q

_________ refers to a permanent change in the DNA

A

Mutation

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3
Q

mutations affecting __________ cells can result in tumors or developmental malformations

A

somatic cells

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4
Q

what is a Point mutations (missense mutation)? what is an example of a point mutation?

A

single nucleotide base substituted.

Example: sickle cell anemia

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5
Q

what is a Frameshift mutation?

A

insertion or deletion of one or two base pairs, altering reading frame of the DNA strand

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6
Q

what occurs during Trinucleotide repeat mutations?

A

amplification of sequence of 3 nucleotides

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7
Q

what is an example of trinucleotide repeat mutations?

A

Fragile X syndrome

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8
Q

permanent genetic changes affecting ________ can be inherited

A

germ cells

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9
Q

what are the 3 types of mendelian disorders?

A

Autosomal Dominant
Autosomal Recessive
Sex-linked (X-linked) Disorders

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10
Q

what are the 2 types of polymorphisms?

A

Single nucleotide polymorphisms

Copy number variations

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11
Q

a _________ is a variation in just one nucleotide (for example, A or T) at a single site on the DNA molecule

A

single nucleotide polymorphism

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12
Q

single nucleotide polymorphisms May be markers for multigenic complex diseases, such as _______ or __________

A

diabetes or hypertension

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13
Q

what are the characteristics of Copy number variation polymorphisms?

A
  • different numbers of large contiguous stretches of DNA, from 1,000 to millions of base pairs
  • About half involve gene-coding sequences
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14
Q

______________ changes result in modulation of gene expression without altered DNA sequence

A

epigenetic changes

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15
Q

_________ of promoter regions in the DNA makes them inaccessible to RNA polymerase

A

Methylation

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16
Q

what type of residues are methylated during epigenetic inactivation?

A

cytosine

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17
Q

_______________ inhibit translation of their target messenger RNAs into their corresponding proteins

A

Micro-RNAs (miRNA’s)

“functions in RNA silencing and post-transcriptional regulation of gene expression”

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18
Q

Autosomal dominant implies that the altered gene locus is on an _________

A

autosome

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19
Q

during what type of disorder will the disease be evident clinically when only ONE of the chromosomes in the pair exhibits a mutation at the affected gene locus

A

autosomal dominant

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20
Q

T/F: The majority of autosomal dominant disorders create outward physical changes

A

true

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21
Q

huntington’s disease is classified as a ___________ disorder

A

autosomal dominant

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22
Q

T/F: Approximately one-quarter of the offspring will have the disease if only one parent is affected with huntington’s disease

A

FALSE

one half of offspring

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23
Q

what is “reduced or incomplete penetrance”?

A

Person has a mutant gene but does not express it phenotypically

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24
Q

_____________ means the trait is seen phenotypically in the individuals having the mutant gene but is expressed differently among individuals

A

variable expressivity

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25
Q

how could a child suffer from an autosomal dominant disorder, but their parents are unaffected?

A

due to “De Novo mutation”

  • the parents don’t have the autosomal dominant gene because their disease arose from a new mutation
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26
Q

_________ disorders represent the largest group of mendelian disorders

A

autosomal recessive disorders

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27
Q

T/F: the parents of people suffering from autosomal recessive disorders usually show similar symptoms as their offspring

A

FALSE

parents are usually asymptomatic

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28
Q

when are rare autosomal recessive diseases usually seen?

A

when the affected child (proband) is the product of a consanguineous relationship

(INCEST Y’ALL)

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29
Q

what are the characteristics of all autosomal recessive disorders?

A

• Two germline mutations (one from each parent)
to develop disease

  • Equally transmitted by men and women
  • 25% of offspring; horizontal pattern in family
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30
Q

Many autosomal recessive disorders present with _______ defects that produce inborn errors of metabolism

A

enzyme

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31
Q

_________ individuals of autosomal recessive disorders will often show reduced, but not complete mutation/inactivity, of the normal enzyme

A

heterozygous individuals

AKA “carriers”

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32
Q

X-linked disorders are also known as “_________” disorders

A

sex-linked

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33
Q

T/F: although rare, Y-linked genetic disorders do occur

A

FALSE

  • nobody has ever found a y-linked disorder (thanks dad)
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34
Q

what is the only trait that has been linked to the y-chromosome?

A

hairy ears

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35
Q

Almost all X-linked disorders are __________ in their inheritance pattern

A

recessive

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36
Q

what inheritance pattern is observed during sex-linked disorders (heterozygosity, homozygosity, et cetera

A
  • women must be homozygous to show disease

- men are heterozygous (mutated X is from the MOTHER)

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37
Q

what occurs during lysonization?

A
  • occurs Sixteen days after conception

- all but ONE X chromosome is randomly inactivated in all of the cells within the zygote

38
Q

what is Unfavorable lyonization?

A

refers to inactivation of an abnormally high percentage of normal X chromosomes

39
Q

the result of ___________ would be the presence of x-linked disorders appearing in heterozygous females

A

unfavorable lysonization

40
Q

Oral-Facial-Digital syndrome (OFD) type 1 is an example of what type of genetic disease?

A

x-linked DOMINANT

41
Q

Marfan syndrome is a autosomal dominant disorder of _________________

A

connective tissue

42
Q

what gene is mutated in Marfan syndrome?

A

the FBN1 gene

43
Q

a mutation of the FBN1 gene (marfan syndrome) will result in abnormal formation of what connective tissue protein?

A

fibrillin

44
Q

what is the prevalence of marfan syndrome?

A

1 in 5,000

45
Q

what are the physical characteristics of someone suffering from Marfan syndrome?

A
  • Tall, thin body habitus with abnormally long legs, arms and fingers
  • Dislocation of lens of the eye
  • Aortic aneurysm and dissection leading to heart failure
46
Q

At least ___ different types of ehler-danlos syndrome may exist

A

6

47
Q

what are the characteristics of Ehlers-Danlos syndrome?

A

Hyperextensible skin and hypermobile joints

Skin fragility and delayed wound healing

Rupture of colon, large arteries

Hernias

48
Q

what is the prevalence of Familial Hypercholesterolemia?

A

1 in 500

49
Q

Familial Hypercholesterolemia result in the mutation of what type of proteins?

A

LDL receptors

50
Q

what is the result of Familial Hypercholesterolemia?

A
  • impaired metabolism and increased LDL cholesterol in the plasma
  • causes xanthomas of the skin and premature atherosclerosis
51
Q

what are the effects on cholesterol for heterozygotes and homozygotes during Familial Hypocholesterolemia?

A

Heterozygotes have 2-3x increased cholesterol levels

homozygotes have over 5x normal levels

52
Q

what are the 2 diseases caused by Mutations in Structural Proteins?

(which 2 impair normal collagen synthesis/function)

A

1) Marfan Syndrome

2) Ehlers-Danlos Syndromes

53
Q

__________________ results from the mutation of a receptor protein

A

Familial Hypercholesterolemia

54
Q

what 2 diseases are caused by by Mutations in genes coding for Enzyme Proteins?

A

1) Phenylketonuria

2) Lysosomal Storage Diseases

55
Q

____________ is an autosomal recessive disorder that affects 1 in 10,000 Caucasian infants

A

phenylketonuria

56
Q

what enzyme is lacking during phenylketonuria? what does this cause?

A
  • phenylalanine hydroxylase

- leads to hyperphenylalaninemia and PKU

57
Q

elevated phenylalanine will have what effects on infants?

A
  • elevated phenylalanine levels impair brain development

- leads to mental retardation

58
Q

what are the characteristics of lysosomal storage diseases?

A
  • Autosomal recessive transmission
  • Commonly affect infants and young children
  • Accumulation of insoluble large molecules (sphingolipids and mucopolysaccharides) in macrophages
59
Q

what are some examples of lysosomal storage diseases?

A

Tay-Sachs disease

Niemann-Pick disease

Gaucher disease

Mucopolysaccharidoses (Hurler & hunter disease)

60
Q

Disorders with Multifactorial Inheritance share what common characteristics?

A
  • Two or more genes responsible, plus environmental, nongenetic influences
  • Frequency of inheritance ranges from 2-7%
61
Q

what causes Mucopolysaccharide storage diseases?

A

Due to lack of any one of several enzymes necessary to degrade mucopolysaccharides

62
Q

what are the physical signs of mucopolysaccharide storage diseases?

A

Affected patients have:
- coarse facial features

  • clouding of cornea
  • joint stiffness
  • mental retardation
63
Q

________ disease is caused by a deficiency of alpha-L-iduronidase

A

Hurler Disease

64
Q

what therapy can help patients with Hurler disease?

A

bone marrow transplants

enzyme treatments

65
Q

Hunter Syndrome is the result of a deficiency of ___________

A

L-iduronate sulfatase

hurler is ALPHA-L-iduronidase

66
Q

what is the inheritance pattern of Hunter syndrome?

A

X-linked inheritance pattern

67
Q

how does Hunter syndrome differ from Hurler syndrome?

A

hunter syndrome shows an absence of corneal clouding and milder clinical course

68
Q

it is estimated that 1 in 200 newborns have a ______________ abnormality

A

chromosomal abnormality

69
Q

A normal chromosomal count (2 X 23 = 46) is termed _______

A

euploid

70
Q

An increased chromosome count that is a multiple of that normally seen (i.e. 3 X 23 or 4 X 23) is termed ___________

A

polyploidy

71
Q

what happens to most cases of polyploidy?

A

spontaneous abortion

72
Q

Any chromosome number that is not an exact multiple of the normal chromosome count is termed _________

A

aneuploidy

73
Q

_____________ and __________ are both examples of aneuploidy

A

trisomy (extra chromosome)

and

monosomy (lacking 1 chromosome)

74
Q

________________ is the transfer of a part of one chromosome to another nonhomologous chromosome.

A

Translocation

75
Q

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

A

Inversion

76
Q

what causes down syndrome?

A

a trisomy (3rd copy) of the 21st chromosome

77
Q

what factor plays the greatest role in the likelihood of down syndrome?

A

advanced maternal age

78
Q

________________ of chromosome 21 during formation of the ovum is the cause of down syndrome

A

meiotic non-disjunction of chromosome 21

79
Q

what are the 2 Cytogenetic Disorders Involving Sex Chromosomes?

A

1) Klinefelter Syndrome
2) Turner Syndrome

***down’s syndrome is NOT on the sex chromosome

80
Q

____________ is Defined as male hypogonadism that develops when there are at least two X chromosomes and one or more Y chromosomes

A

Klinefelter Syndrome

81
Q

what causes Turners syndrome?

A

Due to partial or complete absence of one of the X

chromosomes

82
Q

what are the symptoms of turners syndrome?

A 
Markedly short stature
webbing of the neck
low posterior hairline
shield-like chest
high-arched palate
variety of congenital cardiovascular malformations
failure to develop secondary sex characteristics
primary amenorrhea
83
Q

what techniques can be used to diagnose genetic diseases?

A

1) Fluorescence in situ Hybridization (FISH)
2) Comparative Genomic Hybridization
3) molecular diagnosis (PCR amplification)

84
Q

what are the indications for PRENATAL genetic testing?

A

Mother’s age >34 years

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

85
Q

what are the indications for POSTNATAL genetic testing?

A

Multiple congenital anomalies

Unexplained mental retardation and/or developmental delay

Suspected aneuploidy (e.g., Down syndrome)

Suspected sex chromosomal abnormality

Infertility

Multiple spontaneous abortions

86
Q

what is an autosomal dominant disease that has nearly 100% penetrance, but has extreme variability in its expression?

A

neofibromatosis

87
Q

“Hemophilia A” is an example of what class of inherited disorder?

A

x-linked

88
Q

what genetic disorder will commonly cause an enlarged tongue?

A

Down syndrome

89
Q

_______________ (a sex chromosome disorder) will increased the frequency of taurodontism

A

Klinefelter Syndrome

90
Q

most people with ________________ will have a genotype of 47,XXY

A

Klinefelter Syndrome

91
Q

what is the genotype for people with Turners syndrome?

A

45,X

gen-path 2 (7 decks)

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