Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Molecular Diagnostics > Aneuploidies (somatic and sex) > Flashcards

Aneuploidies (somatic and sex) Flashcards

1
Q

What are the three aneuploidies common with postnatal survival?

A

Trisomy 21, 18, 13

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the prevalence of Down syndrome?

A

1:660-1:700

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are some of the general features of T21?

A

hypotonia, hyperflexiblty of joints, small stature, learning disability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What hand/feet malformations are seen in T21?

A

clinodactlyly, single transverse palmar crease, gap btwn 1st and 2nd toe, crease btwn 1st and 2nd toe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are common cardiac malformations in T21?

A

atrioventricular setpal defect
patent ductus ateriosis
ventricular septal defect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are common GI tract features in T21?

A

duodenal atresia (double-bubble)
anal atresaia
agangliosis of colon
reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are common MSK features of T21?

A

11 pairs of ribs vs. 12

predisposition to hip dislocation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the cytogenetic findings with T21?

A

95% result from nondisjunction
3-4% result from Robertsonian translocation (usually 21q w/ an acrocentric chromosome -> 14 or 22) - no relation w/ maternal age
1-2% mosaicism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Prenatal issues seen in T21?

A

at least 20% are SB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Infant features of T21?

A 
hypotonia
poor moro relfex
increased flexiblty of joints
excess nucahl skin
flat facial profile
upslanting eyes
small ears
clinodactylly 
transverse palmar crease
congenital heart defect (roughly 50%)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Features seen in children with T21? Guidance?

A

hearing loss -> hearing screens, tubes may help prevent infection and improve hearing
delayed tooth eruption and growth
celiac disease (7-16%)
hypo- and maybe hyperthyroidism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Eye features in children w/ T21?

A

should see an ophthalmologist
cataracts (congenital or acquired)
thinning and stretching of cornea is common

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Individuals with Down syndrome have an increased lifetime risk of this cancer:

A

Leukemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Features seen in adults with Down syndrome?

A

early-onset Alzheimer’s disease (in their 40s)
incontinence
hearing loss
infertility in males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Trisomy 18 is also known as:

A

Edward syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the incidence of trisomy 18?

A

1:6000-1:8000 birth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do we note the karyotype of an individual with Edward syndrome?

A

47,XX,+18

47,XY,+18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which sex seems to survive to term more in pregnancies affected by trisomy 18?

A

Females (3:1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the features seen in T18?

A 
prominent back of the skull
unusual ears
small mouth and jaw
clenched hands 
flexed big toes w/ prominent heels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What general characteristics do we see in pregnancies with t18?

A 
poor fetal movement
1/3 premature
1/3 past due date
polyhydramnios
single umbilical artery
hypertonicity postnatally
abdominal hernia
males w/ undescended testes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the survival stats for infants born with trisomy 18?

A

50% mortality within the 1st wk

most don’t live past a year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What syndrome is also known as trisomy 13?

A

Patau syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the incidence of trisomy 13?

A

1:12,000 live birth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What features are seen in more than 50% of trisomy 13?

A 
Cleft lip and palate
small for gestational age
postaxial polydactyly
clenched hands (outer finger overlapping middle)
CNS issues
Holoprosencephaly (severe -> cyclopia)
microcephaly
sloping forehead
congenital heart defect
renal issues
undescended testes or hypoplastic ovaries
rocker bottom feet
cutis aplasia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are some other features seen in trisomy 13?

A

hydrocephalus
spina bifida
omphalocele
kidney abnormalities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Inactivated Xs replicate _______ than active ones.

A

slower

27
Q

What parts of the X chromosome lead to their inactivation?

A

CpG islands are highly methylated regions -> inactivation

28
Q

What percentage of genes on the X chromosome escape inactivation? On which arm are most of them located?

A

10-15%

more on Xp than Xq

29
Q

Xp is associated with what physical feature? Xp and Xq?

A

stature

ovarian function

30
Q

Where is the X inactivatin center located?

What gene is associated with this?

A

Xq13

XIST

31
Q

What is the product and function of XIST?

A

noncoding RNA

stays closely associated w/ inactive X (only expressed from inactive X)

32
Q

X inactivation is random unless?

A

there is an abnormal X chromosome

there is an x;autosome translocation

33
Q

Which X is inactivated if there is an abnormal X?

A

the abnormal X is preferentially inactivated

ex: Xi (isochromosome)

34
Q

Which X is inactivated when there is an x; autosome translocation?

A

If translocation is unbalanced -> abnormal X is inactivated

if translocation is balanced -> normal X is inactivated

35
Q

What syndrome is written as 45,X?

A

Turner syndrome

36
Q

What is the incidence of Turner syndrome?

A

1:4000 live births

37
Q

what are the major features of Turner syndrome?

A 
low posterior hairline (looks like short neck)
swelling of hands and feet
broad chest and wideset nipples
short stature
ovaries not developed
unusual shape and rotation of ears
narrow maxilla or palate
micrognathia
38
Q

What cardiac abnormalities are seen in individuals with Turner syndrome? Which is emergent? What procedure should they have to assess?

A 
bicuspid aortic valve
coarctation of the aorta (urgent)
aortic valve stenosis 
hypoplastic left heart
mitral valve prolapse

echocardiogram

39
Q

What are the cytogenetics seen with Turner syndrome?

A 
50% 45,X
15% 46,X,i(Xq)
15% 45,X/46,XX mosaic
5% 45,X/46,X,i(Xq) mosaic
10% other abnormal karyotypes

ring X chromosome
Long arm deletion
short arm deletion

40
Q

What gene is associated with short stature? Where is it located?

A

SHOX
Xp22.3
Yp11.3
located in pseudoautosomal region - errors in recombination can interfere

41
Q

What cognitive features are seen in Turner syndrome?

A

intelligence at or above the average
deficient in spatial perception, perceptual-motor organization, and fine motor execution
nonverbal IQ is lower than verbal IQ

42
Q

How is Turner syndrome treated?

A 
growth hormone
estrogen therapy (12-14yrs)
43
Q

What adult issues are seen in individuals with Turner syndrome?

A 
osteoporosis
bone fractures
insulin resistance (diabetes)
hypertension
obesity
hyperlipidemia
hearing loss
44
Q

Turner syndrome prenatal outcomes? INdications?

A

seen in 1-2% of conceptus
99% result in spontaneous abortion
single X is usually of maternal origin

nuchal thickening (up to cystic hygroma)
swelling/fluid
growth delay
45
Q

What karyotype do we see in Klinefelter syndrome?

A

47,XXY

46
Q

What’s the incidence of Klinefelter syndrome?

A

1:1000 male births

47
Q

What are the physical features of Klinefelter syndrome?

A

tall
small testes and penis
delayed puberty
breast development

48
Q

What behavioral issues are common in Klinefelter syndrome?

A 
learning problems
below average verbal comprehension and ability
shyness and unassertiveness
apparent immaturity
passivity
49
Q

What are the cytogenetics seen in Klinefelter syndrome?

A

50% of errors in paternal meiosis (failure of normal Xp/Yp recombination)
maternal issues: most meiosis I, others in II, or postzygotic errors -> mosaicism (increase with age)
15% of individuals are mosaic
more Xs, more severe cognitive deficits

50
Q

How can we treat Klinefelter syndrome?

A

hormone treatment

refer to endocrinolgoy

51
Q

What are some other trisomies and their features?

A

47, XXX
1:1000
taller, usually fertile, 70% have learning problems, offspring have increased risk of chromosome abnormality

47,XYY
tall, increased educational and behavioral problems, normal IQ, fertility usually normal

52
Q

What gene is associated with male differentiation? Where is it located?

A

SRY
near pseudoautosomal region
briefly expressed early in development to cause differentiation of testes

53
Q

When do the gonads begin to differentiate? What happens if there’s no SRY or it’s ineffective?

A

around wk 6 of development

ovaries develop

54
Q

What karyotypes are common in DSDs?

A

46,XX male

46,XY female

55
Q

What often causes infertility in men? What gene(s) are associated? Should men be referred for genetic testing? If so, what?

A

Azoospermia
AZF gene clusters
yes, if it is idiopathic -> karyotype and Y chromosome-specific testing

56
Q

What is uniparental disomy?

A

form of nondisjunction where both chromosomes are inherited from same parent

57
Q

What is isodisomy?

A

same sister chromosomes

58
Q

what is heterodisomy?

A

same homolgoues inherited frome same parent

59
Q

What is the typical cause of UPD?

A

trisomy rescue -> cell’s attempt to return to disomic state in trisomic conceptus

results from 2nd nondisjunction event in early, postzygotic mitotic division

60
Q

22q11.2 deletion is typically detected by

A

CMA (microarray)

61
Q

What two conditions are common genomic imprinting disorders?

A

Prader-Willi

Angelman

62
Q

What genes are associated with male development?

A

SRY

TDF

63
Q

Infertility in men can be associated with what changes? Where are these found?

A

AZF gene cluster
AZFa, AZFb, AZFc
Yq

Molecular Diagnostics (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions