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Pathology > Chapter 5 - Genetic Disorders > Flashcards

Chapter 5 - Genetic Disorders Flashcards

1
Q

mutations that alter the meaning of the sequence of the encoded protein

A

missense mutation (type of point mutation)

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2
Q

what type of mutation is the sickle cell mutation

A

missence mutation - CTC for glutamic acid is changed to CAC for valine

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3
Q

mutation that changes an amino acid codon to a chain terminator

A

stop codon or nonsense mutation (type of point mutation)

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4
Q

what type of mutation is the B0-thalassemia mutation

A

stop codon nonsense mutation (CAG for glutamine is changed to UAG stop codon)

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5
Q

small deletion or insertions that lead to an altered reading of DNA

A

frameshift mutations (insertion/deletion mutations)

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6
Q

Tay Sachs is what type of mutation

A

frameshift mutation

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7
Q

amplification of a sequence of three nucleotides

A

trinucleotide repeat mutations

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8
Q

fragile X syndrome is what type of mutation and what is this disorder?

A

tandem repeats of CGG within the fene called familial mental retardation 1 (FMR1)

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9
Q

how do mendelian disorders affect genes

A

they are a result of mutations in single genes

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10
Q

G6PD follows what type of genetics

A

X-linked recessive; red cell hemolysis in patients receiving certain types of drugs

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11
Q

Vitamin D-resistant rickets has what type of genetics

A

X-linked dominant

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12
Q

what type of genetics does Marfan syndrome have?

A

autosomal dominance

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13
Q

what is the mutation in marfan syndrom

A

fibrillin-1

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14
Q

role of fibrillin in the extracellular matrix

A

fibrillin microfibrils in the ECM provide a scaffolding on which tropoelastin is deposited to form elastic fibers

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15
Q

what chromosome is the fibrillin gene mapped on

A

15q21.1 (FBN-2 is on 5q23.31, not in rapid review)

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16
Q

skeletal deformities present in marfan syndrome

A

exceptionally long extremities and long, tapering fingers and toes

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17
Q

what organs may be affected in marfan syndrome

A

skeletal, eye, cardio

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18
Q

what is the ocular change associated with marfan syndrome

A

ectopia lentis - bilateral subluxation/dislocation of the lens

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19
Q

what cardiovasuclar malformations are present in marfan syndrome, which is a leading cause of death

A

MVP and dilation of the ascending aorta due to cystic medionecrosis, dilation of aorta is most serious

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20
Q

major cause of death in Marfan syndrome

A

rupture of an anortic dissection

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21
Q

ehlers danlos syndrome has a defect in _________

A

fibrillar collagen

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22
Q

symptoms of ehlers danlos syndrome

A

Skin is hyperextensible, stretchy, fragile, and vulnerable to trauma. Joints are hypermobile

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23
Q

internal complications associated with ehlers danlos syndrome

A

(1) rupture of thhe colon and large arteries (vascular EDS) (2) ocular fragility with rupture of cornea and retinal detachment (kyphoscoliosis EDS) (3) diaphragmatic hernia (classical EDS)

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24
Q

which type of collagen manifests as the vascular type of EDS

A

type III collagen

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25
Q

the arthrochalasia type of ehlers danlos is a defect in what type of collagen

A

collagen type I, procollagen to collagen

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26
Q

mutation in familial hypercholestolemia

A

gene encoding receptor for LDL

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27
Q

features of heterozygoes with familial hypercholesterolemia

A

2x/3x elevations in plasma cholesterol, skin xanthomas and premature atherosclerosis in adult life

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28
Q

features of homozygotes with familial hypercholestorlemia

A

5x/6x elevations in plasma cholesterol, skin zanthomas, coronary/cerebral/peripheral vascular atherosclerosis at an early age, MI possible before age 20

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29
Q

what is the LDL receptor’s role physiologically

A

binding of IDL to the liver cell membrane and it recognizes both apoprotein B-100 and apoprotein E

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30
Q

how many mutations of the LDL receptor in familial hypercholesterolemia

A

more than 900 mutations involving the LDL receptor gene

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31
Q

what is there an accumulation of in tay-sachs disease

A

Gm2 gangliosides

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32
Q

the mutation in tay-sachs disease causes a deficiency of:

A

hexosaminidase A

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33
Q

what group of people is tay-sachs disease prevalent in

A

Ashkenazi Jews

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34
Q

what is the genetics of tay-sachs disease

A

autosomal recessive

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35
Q

symptoms of tay-sachs disease

A

progressive neurodegeneration, developmental delay, cherry-red spot on macula, lysosomes with onion skin, no hepatomegaly (unlike niemann-pick)

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36
Q

What disease is this seen? and what is it?

A
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37
Q

What disease is this seen in?

A

Tay-sachs; portion of a neuron with prominent lysosomes whorled configurations

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38
Q
A
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39
Q

pattern of inheritance in niemann-pick disease

A

AR

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40
Q

which type of niemann-pick disease does organomegaly present without CNS involvement

A

type B

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41
Q

what are some characteristics of of Niemann-Pick Disease Type A

A

severe infantile form with extensive neurologic invovlement with marked visceral accumulations of sphingomyelin, and progressive wasting and early death within the first 3 years of life

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42
Q

electron microscopy of niemann-pick disease reveals

A

engorged secondary lysosomems that often contain membranous cytoplasmic bodies that resemble concentric lamellated myelin figures (zebra bodies)

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43
Q

what organs are enlarged with niemann pick disease

A

hetosplenomegaly

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44
Q

what disease is this

A

niemann pick disease in liver with hepatocytes and kupffer cells with a foamy vacuolated appearance because of lipid deposition

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45
Q

what is the build up in niemann pick diseases A and B

A

sphingomyelin due to an inherited deficiency of sphingomyelinase

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46
Q

most common type of niemann pick disease

A

type C niemann pick with NPC1, sometimes NPC2 mutation

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47
Q

inheritance pattern of gaucher disease

A

autosomal recessive

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48
Q

mutation invovles what enzyme for gaucher disease

A

glucocerebrosidase

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49
Q

where does the glucocerebrosides accumulate in gaucher disease

A

distended phagocytic cells in the spleen, bone marrow, lymph nodes, tonsils, thymus, and peyer’s patches

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50
Q

histologic appearance of cells in gaucher disease

A

fibrillary type of cytoplasm like crumpled tissue paper

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51
Q

what organ is mostly involved in gaucher disease

A

splenomegaly

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52
Q

what disease do you see these types of cells in

A

gaucher disease; gaucher cells - cytoplasm with the appearance of crumpled cytoplasm

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53
Q

general features of mucopolysaccharidose disorders

A

progressive disoders characterized by coarse facial features, clouding of the cornea, joint stiffness, and mental retardation

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54
Q

pattern of inheritance for hurler syndrome

A

AR

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55
Q

deficiency in hurler syndrom

A

alpha-1-iduronidase

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56
Q

in adition to the MPS symptoms, what are some characterisitics of hurler syndrome

A

growth is retarded with coarse facial features and skeletal deformities

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57
Q

when/how does death occur in hurler syndrome

A

death bye 6-10 years due to carciovascular complications

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58
Q

accumulating metabolite in hurler syndrome (MPS I H)

A

dermatan sulfate, heparan sulfate

59
Q

inheritance pattern for hunter syndrome

A

X-linked recessive

60
Q

what is the enzyme deficiency of Hunter syndrome

A

L-Iduronosulfate sulfatase

61
Q

how does hunter syndrome differ from hurler syndrome

A

it is a milder form of hurler’s syndrome with aggressive behavior and no corneal clouding

62
Q

what accumulates in hunter’s syndrome

A

heparan sulfate and dermatan sulfate

63
Q

inheritance pattern of alkaptonuria

A

autosomal recessive

64
Q

enzyme deficency in alkaptonuria, and what is this enzyme in control of

A

lack of homogentistic oxidase which converts homogentistic acid to methylacetoacetic acid in the tyrosine degradation pathway

65
Q

what is excreted in alkaptonuria

A

urine turns black if its allowed to stand and undergo oxidation when the built up homogentisic acid is secreted

66
Q

what is the most serious consequence from alkaptonuria

A

homogentisic acid deposits in the articular cartilages of the joints causing the cartilage to lose its normal resiliency and become brittle and fibrillated

67
Q

what regions of the body is ochronosis seen in alkaptonuria

A

blue black pigmentation most evident in ears, nose, and cheeks

68
Q

what is the deficient enzyme of metachromatic leukodystrophy

A

arylsufatase A

69
Q

what builds up in metachromatic leukodystrophy

A

sulfatide

70
Q

what is the deficient enzyme in krabbe disease

A

galactosylceramidase

71
Q

what builds up in krabbe disease

A

galactocerebroside

72
Q

enzyme deficiency in von gierke disease

A

G6PD - type 1 glycogen storage disease

73
Q

what organs are involved in von gierke diseases

A

hepatomegaly and renomegaly

74
Q

clinical manifestation of von gierke disease

A

hypoglycemia

75
Q

enzyme deficiency in McArdle syndrome

A

Muslce phosphorylase - type V glycogen storage disease

76
Q

morphologic changes wih McArdle syndrome

A

skeletal muscle accumulations only

77
Q

clinical manifestations of McArdle syndrome

A

painful cramps associated with strenuous exercise

78
Q

what is the age of onset in McArdle syndrome and explain lactate levels in this disease

A

in adulthood (greater than 20 years); muscular exercise fails to raise lactate level in venous blood

79
Q

enzyme deficiency in pompe disease

A

enzyme deficiency of lysosomal glucosidase (acid maltase) - miscellaneous type of glucagen storage disease

80
Q

morphologic changes in pompe disease

A

massive cardiomegaly and cardiorespiratory failure within 2 years

81
Q

the important glycogen storage disease have what mode of inheritance

A

AR

82
Q

in what disease will this change occur in the myocardium

A

pompe disease (glycogen storage disease type II) - normal is on left. right picture has myocardial fibers full of glycogen which is seen as clear spaces

83
Q

most common cause of trisomy and down syndrome

A

nondisjunction

84
Q

what has a strong influence on the incidence of trisomy 21

A

maternal age

85
Q

how often does trisomy occur in births in women under age 20 and over 45

A

1150 live births in women under 20 and 1/25 for mothers over 45

86
Q

other than nondisjunction, what is the genetic abnormality found in Down syndrome

A

robertsonian translocation

87
Q

how much mosaicism goes on with down syndrome?

A

1% of patients are mosaics

88
Q

what type of down syndrome does maternal age affect

A

nondisjunction; translocatioin or mosaic down syndrome are not affected by maternal age

89
Q

diagnostic clinical features of down syndrome (4)

A

flat facial profile with epicanthic folds, abundant neck skin, simian crease on hand, hypotonia, mental retardation, congenital herat defects, predisposition to leukemia

90
Q

what is responsible for the majority of death in infancy/childhood of Down syndrome patients?

A

cardiac problems

91
Q

what cardiac abnormalities are commonly present with Down syndrome

A

defects of the endocardial cushion (most common) like ASDs and VSDs.

92
Q

what congenital malformations other than cardiac problems are present with Down syndrome

A

atresias of the esophagus and small bowel

93
Q

children with trisomy 21 have an increased risk of developing _______

A

acute leukemia, ALL and AML (megakaryoblastic leukemia commonly)

94
Q

Down syndrome patients that are older than 40 can develop

A

Alzheimer disease

95
Q

edwards syndrome is trisomy ___

A

18

96
Q

clinical features of edwards syndrome

A

mental retardation, overlapping fingers, congenital heart defects (VSD)

97
Q

patau syndrome is trisomy __

A

13

98
Q

clinical features of patau syndrome

A

early death, mental retardation, polydactyly, cleft lip and palate, cardiac defects (VSD), renal defects (cystic kidneys)

99
Q

genetic abnormality of DiGeorge syndrome

A

22q11.2, small deletion of band q11.2 on the long arm of chromosome 22

100
Q

symptoms of DiGeorge syndrome

A

thymic hypoplasia with T-cell immunodeficiency, parathyroid hypoplasia (hypocalcemia), cardiac malformations with the outflow tract, and mild facial anomalies

101
Q

clinical features of velocardiofacial syndrome (subtype of DiGeorge)

A

facial dysmorphism (prominent nose, retrognathia), cleft palate, cardiovascular anomalies, learning disabilities

102
Q

what determines male sex

A

presence of a single Y chromosome

103
Q

klinefelter syndrome is genetically defined as

A

male hypogonadism occurring with 2 or more X chromosome and 1 or more Y chromosome

104
Q

clinical features of klinefelter syndrome

A

eunuchoid body habitus with abnormally long legs, small atrophic testes associated with a small penis, lack of secondary mal characteristics like a deep voice, beard, and male distribution of pubic hair, gynecomastia, lower mean IQ but not mental retardation

105
Q

abnormal hormone levels found in klinefelter syndrome

A

elevated FSH and reduced testosterone levels

106
Q

appearance of testes with klinefelter syndrome

A

some patients have totally atrophied testicular tubules that are replaced by pink, hyaline, collagenous ghosts; others have atrophic tubules that are interspersed

107
Q

appearance of leydig cells with klinefelter syndrome

A

leydig cells appear prominent as a result of atrophy and crowding of tubules and increased gonadotropin concentrations

108
Q

classic klinefelter karyotype, and what does it result from

A

47,XXY from nondisjunction

109
Q

turner syndrome results from ____ and is characterized by ____ in phenotypic females

A

complete/partial monosomy of the X chromosome, hypogonadism

110
Q

most common karyotype of turner syndrome

A

45, X karyotype

111
Q

most severely affected patients with turner syndrome present in infancy with these clinical features:

A

edema of the dorsum of the hand and foot because of lymph stasis, swelling of the nape of the neck (markedly distended lymphatic channels producing cystic hygroma), b/l neck webbing, persistant looseness of the skin on the back of the neck, congenital heart disease (preductal coarctation of the aorta and bicuspid aortic vlve most common)

112
Q

clinical features seen in the adolescent andd adult form of Turner syndrome

A

failure to develop normal secondary sex characteristics, short stature (lower than 150cm), amenorrhea

113
Q

most important cause of primary amenorrhea (1/3 of cases)

A

turner syndrome

114
Q

most common sex chromosome abnormality in females

A

turner’s syndrome

115
Q

describe what happens to the oocytes and what do the ovaries look like in turner’s syndrome

A

without the second X chromosome there is an accelerated loss of oocytes which is complete by age 2 years; ovaries are reduced to atrophic fibrous strands devoid of ova and follicles called streak ovaries

116
Q

most common form of male pseudohermaphroditism and what is its cause and mode of inheritance

A

complete androgen insennsitivity syndrome (testicular feminization) from mutations in the gene encoding the androgen receptor, X-linked recessive

117
Q

fragile-x syndrome gene, protien, and repeat

A

FMR1 (familial mental retardation-1 gene), FMR-1 protien, CGG

118
Q

friedreich ataxia gene, protein, repeat

A

FXN, frataxin, GAA

119
Q

myotonic dystrophy gene, protein, repeat

A

DMPK, myotonic dystrophy protein kinase (DMPK), CTG

120
Q

spinobulbar muscular atrophy/kennedy disease gene, protein, repeat

A

AR, androgen receptor AR, CAG

121
Q

huntington disease gene, locus, protein, repeat

A

HTT, 4p16.3, huntingtin, CAG

122
Q

spinocerebellar ataxia trinucleotide repeat

A

CAG

123
Q

second most common genetic cause of mental retardation (after Down syndrome)

A

fragile-x syndrome

124
Q

clinical features of fragile-X syndrome in males

A

mentally retarded males, with a long face with a large mandible, large everted ears, and large testicles (macroorchidism - 90% of post-pubertal males!)

125
Q

how often is it to have a carrier female be affected in fragile x-syndrome

A

30% to 50% of carrier females affected with mental retardation which is a higher number than that of other x-linked recessive disorders

126
Q

mode of inheritance for fragile-x syndrome

A

x-linked

127
Q

choice for diagnosis of fragile-x syndrome

A

PCR-based detection of the repeats

128
Q

example of a disease with mitochondrial inheritance

A

leber hereditary optic neuropathy - a neurodegenerative disease that manifest as a progressive b/l loss of central vision

129
Q

what is genomic imprinting

A

imprinting selectively inactivates either the maternal or paternal allele; occurs in the ovum/sperm before fertilization and then is transmitted to all somatic cells through mitosis

130
Q

prader-willi syndrome characteristics

A

mental retardation, shrot stature, hypotonia, obesity, hypogonadism

131
Q

genetic abnormality in prader-willi syndrome

A

deletion in the paternally derived chromosome 15 (paternal imprinting)

132
Q

angelman syndrome genetic abnormality

A

deletion of maternally derived chromosome 15 (maternal imprinting)

133
Q

symptoms found in angelman syndrome

A

mental retardation, ataxic gait, seizures, inappropriate laughter

134
Q

what are angelman syndrome patients sometimes referred to as?

A

happy puppets :/

135
Q

what does PCR do to DNA and what are the steps invovled

A

amplifies a desired fragment of DNA; denaturation (heat to generate 2 strands), annealing (in cooling, excess premade DNA primers anneal to specific sequeneces on the DNA needing to be amplified), elongation (heat stable DNA polymerase replicates following each DNA primer)

136
Q

blotting procedures: each blot is used for what molecule?

A

SNoW DRoP (southern = DNA, northern = RNA, western = protien)

137
Q

process of southern blotting

A

DNA sample electrophoresed to gel then to filter –> filter soaked in denaturant and exposed to radiolabeled DNA probe –> DNA probe recognizes the sample and anneals to the complementary strand –> ds DNA is visualized when filter is exposed to film

138
Q

when would you use a southern blot over PCR

A

if the affected DNA segment is too large

139
Q

process of microarraying

A

thousands of nucleic acid sequences arranged in grids on glass/silicon –> DNA/RNA probes hybridize to the chip and scanner detects the amount of complementary binding

140
Q

what is microarray used for? what is it able to detect?

A

you look at thousands of genes simultaneousl; they detect single nucleotide polymorphisms (SNPs)

141
Q

use of FISH! (flluorescence in situ hybridization)

A

specific localization of genes and direct visualization of anomalies at a molecular level (if the deletion is too small to be visualized on a karyotype)

142
Q

what does the fluorescence indicate on FISH

A

fluorescence is present when the gene is present, if there is no fluorescence the gene has been deleted

143
Q

FISH method

A

fluorescent DNA or RNA probe binds to specific gene site of interest on chromosomes

Pathology (9 decks)

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