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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
What adjunct tests are done in individuals with trisomy 21
TSH as prevention (hypothyroid) | Neck XR to assess stability of atlas-axis (needed for special olympics)
26
What is duodenal atresia
absence or complete closure of duodenum Causes bilious vomiting and obstruction XR: double bubble sign associated with trisomy 21
27
Trisomy 18 presents with
``` Clenched hand with overlapping fingers prominent occiput rocker bottom feet* Micrognathia Umbilical hernia 95% die in the 1st year of life ```
28
What is Turner syndrome
Monosomy XO (only 1 X chromosome)
29
Infant characteristics of Turner syndrome are
``` webbed neck low hair line Lymphedema* (peripheral) Generalized edema *Co-arctation of the aorta (w/ bicuspid valve) ```
30
Turner syndrome presents with
``` 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
What is FISH testing
Fluorescence In Situ Hybridization Special chromosome testing for microdeletions, DiGeorge syndrome, Prader-Willi sundrome, Angelman syndrome, Trisomy, and more
32
What is CGH testing
Comparative Genomic Hybridization testing | Use patient vs control DNA, hybridize to microarray, measure fluorescence levels, and computer generates a plot
33
What is in the AZ newborn screen
Endocrine*, Hemoglobinopathies, Biotinidase deficiency, Galactosemia, Amino acid disorder*, Fatty acid oxidation d/o, Organic acid d/o, Urea cycle, Cystic Fibrosis
34
When do you take your sample for a newborn screen
1st: at the hospital within 24 hours of life 2nd: in the clinic, 5-14 days post birth
35
How do you get the serum sample for a newborn screen
Take blood from the heel
36
How do you preform a metabolic screen
1st screen done in hospital | 2nd screen done >5 days old
37
What should you do if you get an abnormal metabolic screen
Correlate clinically, Repeat** the screen and refer to peds sub-specialty of involvement Ex: PKU
38
Common inborn errors of metabolism are
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
What is the screening test for PKU
Increased phenylalanine levels on serum test | This is because phenylalanine hydroxylase can't break phenylalanine down into tyrosine, to Phe builds up
40
What is PKU
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
How can you treat PKU
Restrict phenylalanine in diet!
42
How do you test for congenital hypothyroidism
Serum TSH level; will be HIGH in hypothyroidism
43
How does congenital hypothyroidism manifest
Newborn: large posterior fontanelle, prolonged jaundice, macroglossia, hoarse cry, umbilical hernia, constipation Kid: mental retardation, poor growth
44
How do you treat congenital hypothyroidism
Thyroid replacement (thyroxine)
45
How do you screen for congenital adrenal hyperplasia
17-OH hydroxylase will be elevated on a serum test
46
What are Sx of CAH
Atypical genitalia (emergency) Early puberty Short stature
47
How does CAH 21-OH deficiency present in males
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
How does CAH 21 hydroxylase deficiency present in females
Ambiguous genitalia Virilization + salt wasting S/Sx (hypoNa, hypoK, hypoglycemia, vomiting, shock, dehydration
49
What are examples of genetic imprinting syndromes
``` Prader-Willi (missing Paternal 15q11-q13 allele) AngelMan syndrome (missing 15q-q13 Maternal allele) ```
50
How do you test for Prader-Willi and Angelman syndrome
FISH probe- microdeletions
51
How does Prader-Willi present
``` Infant: severe hypotonia, FTT Obesity Small hands and feet Hypogonadism Mental retardation ```
52
How does Angelman syndrome present
Happy puppet: jerkey ataxia, uncontrollable bouts of laughter Fair hair Seizures Severe mental retardation
53
What is Maple Syrup Urine disease
Auto Recessive deficiency of decarboxylase= Leucine, Isoleucine, and Valine products not broken down= build up
54
How does MSUD present
Urine and Hair smell like maple syrup Seizures, Coma, Lethargy Mental retardation
55
How do you test for MSUD
Measure LIV levels in urine and plasma
56
How do you treat MSUD
Dietary restrictions of LIV, enzyme replacement
57
What is Tay-Sachs disease
``` Lysosomal defect (Hexoaminidase A deficiency) causing build up of Ganglioside (a sphingolipid, cholesterol) MC in Ashkenazi Jews and French Canadians ```
58
How does Tay-Sachs disease present
``` Increased infantile startle response Hypotonia Blind (cherry red spot) Clumsy, Awkward Seizures ```
59
What is osteogenesis imperfects
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
What happens in T1 and T2 OI
T1 (MC*): Blue sclera, brittle bones, deafness | T2 (lethal): bony deformities

Summer Disciplines 3 (9 decks)

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