developmental genetics Flashcards

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1
Q

when does gastrulation occur

A

14-28 days

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2
Q

what is gastrulation

A

rearrangement of a single layer into a trilaminar structure

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3
Q

trilaminar structure of gastrulation?

A

ectoderm, mesoderm, and endoderm

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4
Q

what major structural feature forms in the gastrulation phase

A

primitive streak

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5
Q

neurlation?

A

folding process that turns the nueral plate into the neural tube

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6
Q

what type of birth defects does neurlation cause

A

neural tube defects

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7
Q

where does neurulation close at

A

5 diff sites

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8
Q

what does the ectoderm separate into during neurlation

A

neural tube, epidermis, and neural crest cells

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9
Q

when is the mesoderm formed

A

gastrulation

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10
Q

what does the notochord do?

A

induce neural tube and body axis

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11
Q

what does the dorsal mesoderm give rise to?

A

axial skeleton, skeletal muscle, and CT

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12
Q

what does the intermediate mesoderm give rise to?

A

kidneys and GU

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13
Q

what does the lateral mesoderm give rise to?

A

heart, viscera, body wall

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14
Q

what does the mesoderm consist of

A

notochord, dorsal mesoderm, intermediate mesoderm, lateral mesoderm, and head mesenchyme

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15
Q

what layer of the trilamina causes many birth defects

A

mesoderm

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16
Q

what does the endoderm form

A

lining of digestive tract, respiratory tree, middle ear, thymus, thyroid, and parathyroids

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17
Q

purpose of primitive streak

A

crate A/P axis

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18
Q

what does nodal expression do

A

initiates and maintains primitive streak

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19
Q

purpose of Hox genes

A

position cells and tissues

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20
Q

mutations in Hox genes leads to…

A

abnormalities of limb formation

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21
Q

what is situs solitus

A

normal axis formation

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22
Q

what is situs inversus

A

body is a mirror image- appendix on left side

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23
Q

what is situs ambiguous/heterotaxy

A

same on both sides ex: left and right lung both have 3 lobes

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24
Q

what is craniofacial development regulated by

A

Hox genes

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25
Q

1st MC birth defects? 2nd MC birth defects?

A

heart then limb

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26
Q

what embryonic later is limb formation derived from

A

mesoderm

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27
Q

what influences distal progression of limb

A

apical ectodermal ridge

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28
Q

what does the Apical ectodermal ridge stimulate proliferation of

A

mesodermal cells

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29
Q

what does the zone of polarizing activity specify

A

anterior and posterior information

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30
Q

what is key for thumb/finger differentiation

A

zone of polarizing activity

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31
Q

what occurs in Holt Oram Syndrome

A

malformations in radial, thenar, and carpal bones, congenital heart disease, cardiac conduction disease

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32
Q

what side of the body is Holt Oram Syndrome more severe in

A

left

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33
Q

what type of congenital heart defects do ppl with Holt Oram Syndrome have

A

ASD and VSD

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34
Q

what can cardiac conduction disease progress to

A

complete heart block with or without atrial fibrillation

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35
Q

what gene is the mutation on in holt oram synd

A

TBX5

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36
Q

organ formation?

A

Common cells and tissues “collaborate” for a unified function

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37
Q

what is skeletal formation dependent upon

A

osteoblasts

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38
Q

what is skeletal formation regulated by

A

transcription factor RUNX2

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39
Q

what do RUNX2 mutations cause

A

cleidocranial dysostosis

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40
Q

clinical features of cleidocranial dysostosis

A

Open fontanelle, Hypertelorism, Absent clavicles

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41
Q

what do PAX 6 gene mutations cause

A

aniridia (no iris)

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42
Q

what do Pax 6 gene mutations cause

A

small eye

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43
Q

ectopic expression?

A

Can manipulate the gene to express in a different location

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44
Q

example of ectopic expression?

A

pax 6 mutations

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45
Q

what are malformation defects due to

A

Defects due to intrinsically abnormal development

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46
Q

how do malformations arise

A

genetic, teratogens, and fetal environment

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47
Q

examples of syndromes with malformations?

A

TAR syndrome
Fanconi anemia
Polydactyly

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48
Q

what are deformation defects due to

A

nondisruptive mechanical force, resulting in abnormal form or position; extrinsic factor

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49
Q

what causes deformations

A

Uterine constraint

Malformation or disruption may contribute

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50
Q

how is the prognosis for deformations

A

good! spontaneous resolution and internal fixation

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51
Q

examples of syndromes with deformations?

A

plagiocephaly, metatarsus adductus (clubfeet)

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52
Q

when do deformations occur

A

Post-conception!

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53
Q

what is a disruption defect due to

A

disruptive mechanical force

54
Q

is disruption genetic

A

no

55
Q

what are the effects of disruption

A

lasting effects since tissue can’t grow back

56
Q

examples of disruptions

A

amniotic bands

57
Q

dysplasia?

A

Anomalous organization of cells or tissues

58
Q

2 types of dysplasia?

A

localized and genralized

59
Q

tell me about localized dysplasia

A

Severity depends on extent of involvement; genetic at cellular level

60
Q

tell me about generalized dysplasia

A

Usually genetic, and heritable with variable expressivity

61
Q

examples of dysplasias

A

skeletal dysplasias

62
Q

what type of inheritance pattern are skeletal dysplasias

A

autosomal dominant; usually new mutations

63
Q

what type of disorder is usually parinatal letal

A

skeletal dysplasias

64
Q

when are skeletal dysplasias detectable

A

in utero

65
Q

spine?

A

spondylo

66
Q

epiphyseal?

A

ossification separated from shaft by epiphyseal cartilage

67
Q

metaphyseal?

A

growth area between epiphyses and diaphyses

68
Q

diaphyseal?

A

shaft

69
Q

localized rhizomatic dysplasia?

A

humerus is shorter than forearm

femur shorter than leg

70
Q

localized mesomelic dysplasia?

A

radius/ulna or tibia/fibula are short

71
Q

localized acromelic dysplasia?

A

hand/foot

72
Q

localized micromelic dysplasia?

A

whole limb

73
Q

what is Thanatophoric dysplasia

A

long trunk and very short curved limbs,flat ossification centers of the vertebral bodies, femora and other bones are very short and usually curved

74
Q

what is achondroplasia

A

rhizometric shortening of long bones, trident hand shape, bowing bc of bone length discrepancy

75
Q

most mutable position in genome

A

achondroplasia gene

76
Q

natural history of achondroplasia

A
Normal intelligence
Motor delays (hypotonia, large head)
77
Q

adult height of someone with achondroplasia

A

50 inches

78
Q

complications of acholdroplasia

A

Otitis media (midface hypoplasia), Respiratory problems and apnea, Foramen magnum compression, Midface hypoplasia, Hydrocephalus

79
Q

diff btwn achondroplasia and hypochondroplasia?

A

similar features of achondroplasia but less pronounced, diagnosed at later age, height 50-65 inches, inc incidence of learning probs and ID

80
Q

mutations in thanatophoric dysplasia, acholdroplasia, and hypochondroplasia are in what gene

A

FGFR3

81
Q

what determines if someone gets thanatophoric dysplasia, acholdroplasia, or hypochondroplasia

A

point mutation location within the gene

82
Q

what are skeletal dysplasias AKA

A

fibroblast growth factors (FGF)

83
Q

what are Craniosynostoses

A

Premature closure of the cranial sutures

84
Q

name the different skeletal dysplasias

A

craniosynostoses, thanatophoric dysplasia, acholdroplasia, and hypochondroplasia

85
Q

what are mutations from Craniosynostoses in

A

FGFR1, FGFR2, FGFR3, TWIST

86
Q

what are the different paracrine signaling families

A

FGF, hedgehogs, Wingless (Wnt), transforming growth factor beta (TGRB)

87
Q

pathway of sonic hedgehog

A

SHH activates PTCH

active PTCH inhibits SMO

88
Q

what is SHH invoolved in

A

axis formation

89
Q

what do mutations in SHH cause

A

holoprosencephaly

90
Q

clinical features of holoprosencephaly

A

Cyclopia

Central maxillary incisor

91
Q

Cyclopia?

A

lack of 2 brain hemispheres

92
Q

what is Smith-Lemli-Opitz syndrome an abnormality in

A

cholesterol metabolism; Deficiency in 7-dehydrocholesterol (7DHC) reductase

93
Q

clinical features of Smith-Lemli-Opitz syndrome

A

Small head and body size
Intellectual disability
Ambiguous genitalia
Y-shaped 2/3 toe syndactyly

94
Q

clinical features of Gorlin syndrome/Nevoid basal cell carcinoma syndrome

A

Multiple basal cell carcinomas
Macrocephaly
Jaw keratocysts

95
Q

what do mutations in PTCH cause

A

Gorlin syndrome/Nevoid basal cell carcinoma syndrome

96
Q

what do mutations in GLI3 cause

A

Greig Cephalopolysyndactyly syndrome

97
Q

clinical features of Greig Cephalopolysyndactyly syndrome

A

Preaxial polydactyly, Macrocephaly, Seizures, hydrocephalus, and intellectual disability in severe cases

98
Q

clinical features of Rubinstein-Taybi syndrome

A

Broad and angulated thumbs and big toes, Postnatal small head and body size, Mod-severe intellectual disability

99
Q

mutations in CREBBP cause what

A

Rubinstein-Taybi syndrome

100
Q

what axis formation are wingess (wnt) responsible for

A

dorsal/ventral

101
Q

what organs do wingless (wnt) form

A

brain, muscle, gonads, and kidneys

102
Q

what disordesr are wingless (wnt) responsible for

A

disorders of limb structure and gonadal development

103
Q

what are Transforming Growth Factor β (TGFBs) associated with formation of

A

bones

104
Q

name some RAS opathies

A

noonan syndrome, LEOPARD syndrome, Costello syndrome, cardio-facio–cutaneous syndrome, NMF1

105
Q

PTPN11 mutations are associated with what

A

noonan syndrome

106
Q

common genetic form of short stature?

A

noonan syndrome

107
Q

MC heart defect in noonan

A

pulmonic stenosis

108
Q

features of noonan

A

short stature, congenital heart defects, undescended testicles, minor learning difficulties

109
Q

mutations in PTPN11, also RAF1 and BRAF are associated with…

A

LEOPARD

110
Q

LEOPARD?

A
Lentigines (freckles) 
ECG abnormalities
Ocular hypertelorism
Pulmonic stenosis
Abnormal genitalia
Retardation of growth
Deafness, sensorineural
111
Q

features of Cardiofaciocutaneous synd

A

CHD, sparse/curly hair, sparse/absent eyebrows, ID, risk for neoplasia (Acute lymphoblastic leukemia)

112
Q

Mutations in BRAF, MAP2K1, MAP2K2, KRAS are assoc with what

A

Cardiofaciocutaneous

113
Q

clinical features of Costello syndrome

A
Severe postnatal feeding difficulties
Short stature
Intellectual disability
Curly, sparse fine hair
Congenital heart disease
114
Q

HRAS mutations are seen in what

A

costello synd

115
Q

features of NMF1?

A

Café-au-lait (coffee with cream) spots
Benign nerve tumors called neurofibromas
Freckling in the inguinal (groin) or axillary (armpit) regions
Eye changes
Learning problems or intellectual disability

116
Q

what happens to the symptoms of NMF over time

A

they get worse; progressive

117
Q

inheritance pattern of NMF 1?

A

autosomal dominant

118
Q

in order for a tumor suppressor gene to be mutated what needs to occur

A

both copies must be mutated

119
Q

in order for a proto-oncogene to be mutated what needs to occur

A

only one copy must be mutated

120
Q

what do protooncogenes do

A

encourage growth

121
Q

with a germline mutation, what cells are mutated

A

ALL cells start out with a SINGLE hit

122
Q

Knudson’s Two-Hit Hypothesis is genotypically _____ and phenotypically______

A

dominant, recessive

123
Q

is variable expressitivity quantitative or qualitative

A

qualitative

124
Q

is penetrance quantitative or qualitative

A

quantitative

125
Q

variable expressitivity?

A

you have the symptoms but to what degree

126
Q

penetrance?

A

do you have symptoms or not?

127
Q

transcription factors

A

Regulate when and how much a gene is transcribed

128
Q

what are many CT disorders caused by

A

EMP dysfunction

129
Q

EMP disorder examples?

A

Marfan syndrome
Collagenopathies including Ehlers-Danlos syndrome
Williams syndrome

130
Q

mutation in FBN1 causes what

A

marfan syndrome

131
Q

marfan features

A

Tall, thin body
long limbs
retinal detachment
risk for aortic root dilation and/or dissection

132
Q

trmt for marfan heart issues?

A

beta blockers, Losartan