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Summer Disciplines 3 > Peds genetics > Flashcards

Peds genetics Flashcards

1
Q

What are some causes of mutations

A 
Multi-factorial 
Spontaneous 
Genetic (chromosomes, gene mutations) 
Environmental (XR, UV, radiation, chemicals) 
Epigenetics
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2
Q

What is epigenetics

A

The study of changes caused by gene expression rather than gene mutation
Gene expression is altered by cell type, disease states, and physiologic stimuli (like stress)

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3
Q

What are the types of gene mutations (change in nucleotide sequence)

A

Silent: the last letter changes, so nothing is seen (TTC-TTT)
Nonsense: first letter changes= STOP! (TTC-ATC)
Missense: middle letter changes= new AA made

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4
Q

What does he want us to know about chromosome mutations

A

You can have changes in the big part of a chromosome, not just the small parts
Ex: deletion, duplication, inversion, substitution, and translocation

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5
Q

What happens in enzyme mutations

A

Either the enzyme has a problem (phenylalanine hydroxylase doesn’t convert Phe to Tyr)
Or the enzyme cofactor does (tetrahydrobiopterin doesn’t convert to phenylalanine hydroxylase= no Phe to Tyr)

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6
Q

What are the inheritance patterns

A

Autosomal dominant: 50% offspring will be affected and show, 50% will be unaffected
Autosomal Recessive: 25% will have d/o, 25% will be normal and not carry, 50% will be carriers

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7
Q

What are reasons an individual who inherits AD disease might not show for it

A

Penetrance

Expressivity

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8
Q

In order for AR pattern to manifest physically, you need

A

two mutant alleles

There is increased risk in small populations and cosanguinity (if both are carriers, 1:4 WILL have it)

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9
Q

What are types of genetic testing

A

Fetal interventions (amniocentesis)
Newborn screen
Chromosome testing (karyotype, FISH, CGH)
Genetic referral or developmental clinc referral for specific gene/enzyme testing

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10
Q

What are indications for prenatal screening tests

A

FHx
Maternal causes (smoking, EtOH, SM, SLE)
Teratogenic exposure
AMA (birth child at 35+ y/o)

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11
Q

What prenatal screening tests can you do

A

Maternal Serum Screen (second trimester, 15-20 wks)
Fetal US
Amniocentesis, chorionic villus sampling

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12
Q

What are you screening for in fetal tests

A

Neural tube defects
chromosomal trisomies
cardiac defects
(and more)

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13
Q

What is polyhydramnios and what can it cause

A

Too much amniotic fluid (>2L)

Duodenal atresia, Gastroschisis, Omphalocele

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14
Q

What is oligohydramnios and what can it cause

A

Too little amniotic fluid

Renal problems, horse shoe kidney

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15
Q

What do you test in maternal serum samples

A

AFP
hCG
Unconjugated estriol
Inhibin A

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16
Q

What can AFP levels tell you

A

Increased: ancephaly, spina bifida, abd wall defects
Decreased: trisomy 21 or 18

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17
Q

What are some neural tube defects

A 
Spina bifida (tuft of hair on lower back) 
Myelomeningocele (actual spinal cord in the meningocele on the lower back)
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18
Q

How can you prevent neural tube defects

A

Mom takes folic acid!!

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19
Q

What can fetal US reveal

A

Nuchal thickness, a sign of trisomy 21

Intracardiac echogenic focus (non-specific cardiac markers)

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20
Q

What is trisomy 21

A

A chromosomal mutation with 3 chromosomes at 21

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21
Q

How do Trisomy 21 individuals present

A

Hypotonia
Facies
Simian crease
Hypoplasia of 5th digit (pinky is short)
Sandal toes (big toe and index are far apart)

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22
Q

Trisomy 21 facies include

A 
flat midface and nasal bridge 
small ears 
epicanthial folds 
brushfield eye spots 
up-slanting palpebral fissures
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23
Q

Other manifestations of trisomy 21 are

A

cardiac defects: AV canal, VSD
GI: duodenal atresia/stenosis, Hirschsprung dz
Endo: Hypothyroid
MSK: atlantoaxial instability
Mental retardation, cataracts, glaucoma, hearing impaired

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24
Q

What test is done to diagnose trisomy 21

A

Karyotype; will see 3 chromosomes on 21

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25
Q

What adjunct tests are done in individuals with trisomy 21

A

TSH as prevention (hypothyroid)

Neck XR to assess stability of atlas-axis (needed for special olympics)

26
Q

What is duodenal atresia

A

absence or complete closure of duodenum
Causes bilious vomiting and obstruction
XR: double bubble sign
associated with trisomy 21

27
Q

Trisomy 18 presents with

A 
Clenched hand with overlapping fingers 
prominent occiput 
rocker bottom feet* 
Micrognathia 
Umbilical hernia 
95% die in the 1st year of life
28
Q

What is Turner syndrome

A

Monosomy XO (only 1 X chromosome)

29
Q

Infant characteristics of Turner syndrome are

A 
webbed neck 
low hair line 
Lymphedema* (peripheral) 
Generalized edema 
*Co-arctation of the aorta (w/ bicuspid valve)
30
Q

Turner syndrome presents with

A 
Short stature 
webbed neck 
low posterior hair line 
broad chest 
widely spaced nipples 
ovarian dysgenesis, amenorrhea 
horseshoe kidneys 
coarctation of aorta, HTN 
*Normal IQ usually!*
31
Q

What is FISH testing

A

Fluorescence In Situ Hybridization
Special chromosome testing for microdeletions, DiGeorge syndrome, Prader-Willi sundrome, Angelman syndrome, Trisomy, and more

32
Q

What is CGH testing

A

Comparative Genomic Hybridization testing

Use patient vs control DNA, hybridize to microarray, measure fluorescence levels, and computer generates a plot

33
Q

What is in the AZ newborn screen

A

Endocrine, Hemoglobinopathies, Biotinidase deficiency, Galactosemia, Amino acid disorder, Fatty acid oxidation d/o, Organic acid d/o, Urea cycle, Cystic Fibrosis

34
Q

When do you take your sample for a newborn screen

A

1st: at the hospital within 24 hours of life
2nd: in the clinic, 5-14 days post birth

35
Q

How do you get the serum sample for a newborn screen

A

Take blood from the heel

36
Q

How do you preform a metabolic screen

A

1st screen done in hospital

2nd screen done >5 days old

37
Q

What should you do if you get an abnormal metabolic screen

A

Correlate clinically, Repeat** the screen and refer to peds sub-specialty of involvement
Ex: PKU

38
Q

Common inborn errors of metabolism are

A

Hypothyroidism: do TSH and free T4
CAH: test 17-hydroxyprogesterone
PKU: test phenylalanine 24 hrs s/p protein intake
Galactosemia: lactose intake then test G1PU electrophoresis

39
Q

What is the screening test for PKU

A

Increased phenylalanine levels on serum test

This is because phenylalanine hydroxylase can’t break phenylalanine down into tyrosine, to Phe builds up

40
Q

What is PKU

A

Enzyme defect where Phe builds up and becomes toxic
Manifests as: blonde, blue eyes, severe mental retardation, autism, seizures, mousy odor
Check for FHx of developmental delay

41
Q

How can you treat PKU

A

Restrict phenylalanine in diet!

42
Q

How do you test for congenital hypothyroidism

A

Serum TSH level; will be HIGH in hypothyroidism

43
Q

How does congenital hypothyroidism manifest

A

Newborn: large posterior fontanelle, prolonged jaundice, macroglossia, hoarse cry, umbilical hernia, constipation
Kid: mental retardation, poor growth

44
Q

How do you treat congenital hypothyroidism

A

Thyroid replacement (thyroxine)

45
Q

How do you screen for congenital adrenal hyperplasia

A

17-OH hydroxylase will be elevated on a serum test

46
Q

What are Sx of CAH

A

Atypical genitalia (emergency)
Early puberty
Short stature

47
Q

How does CAH 21-OH deficiency present in males

A

Salt Wasting Syndrome: Blockage of aldosterone and cortisol increase adrenal androgens
Increase in 17-OH levels, hyponatremia, hyperkalemia, hypoglycemia, metabolic acidosis, increased renin
Vomiting, Shock, dehydration
no PE findings

48
Q

How does CAH 21 hydroxylase deficiency present in females

A

Ambiguous genitalia
Virilization
+ salt wasting S/Sx (hypoNa, hypoK, hypoglycemia, vomiting, shock, dehydration

49
Q

What are examples of genetic imprinting syndromes

A 
Prader-Willi (missing Paternal 15q11-q13 allele) 
AngelMan syndrome (missing 15q-q13 Maternal allele)
50
Q

How do you test for Prader-Willi and Angelman syndrome

A

FISH probe- microdeletions

51
Q

How does Prader-Willi present

A 
Infant: severe hypotonia, FTT
Obesity 
Small hands and feet 
Hypogonadism 
Mental retardation
52
Q

How does Angelman syndrome present

A

Happy puppet: jerkey ataxia, uncontrollable bouts of laughter
Fair hair
Seizures
Severe mental retardation

53
Q

What is Maple Syrup Urine disease

A

Auto Recessive deficiency of decarboxylase= Leucine, Isoleucine, and Valine products not broken down= build up

54
Q

How does MSUD present

A

Urine and Hair smell like maple syrup
Seizures, Coma, Lethargy
Mental retardation

55
Q

How do you test for MSUD

A

Measure LIV levels in urine and plasma

56
Q

How do you treat MSUD

A

Dietary restrictions of LIV, enzyme replacement

57
Q

What is Tay-Sachs disease

A 
Lysosomal defect (Hexoaminidase A deficiency) causing build up of Ganglioside (a sphingolipid, cholesterol) 
MC in Ashkenazi Jews and French Canadians
58
Q

How does Tay-Sachs disease present

A 
Increased infantile startle response 
Hypotonia 
Blind (cherry red spot) 
Clumsy, Awkward 
Seizures
59
Q

What is osteogenesis imperfects

A

Dominant gene defect affecting collagen in the body

Test for this with an XR to see bony deformities or brittle bones- can send for hearing test if T1 and abn bone XR

60
Q

What happens in T1 and T2 OI

A

T1 (MC*): Blue sclera, brittle bones, deafness

T2 (lethal): bony deformities

Summer Disciplines 3 (9 decks)

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