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IBI Test 4 > B3.069 Congenital Disorders and Genetic Testing > Flashcards

B3.069 Congenital Disorders and Genetic Testing Flashcards

1
Q

3 types of genetic disorders

A

single gene disorders
chromosomal disorders
multifactorial inheritance

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2
Q

examples of single gene disorders

A

sickle cell anemia

CF

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3
Q

example of multifactorial inheritance

A

spina bifida

diabetes mellitus

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4
Q

congenital anomalies

A

broad term for birth abnormalities

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5
Q

malformation

A

multiple defects from a single abnormal embryologic event

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6
Q

example of malformation

A

DiGeorge syndrome

incomplete migration of 3rd and 4th pharyngeal arch leads to thymic hypoplasia, cleft palate

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7
Q

deformation

A

abnormality from intrauterine mechanical forces

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8
Q

example of deformation

A

oligohydramnios, limited fluid in womb can lead to club foot, crumpled ears

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9
Q

disruption

A

abnormalities resulting from changes in the intrauterine environment

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10
Q

example of disruption

A

amniotic band sequence

amniotic rupture results in tendons to amputations of extremities

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11
Q

loss of function mutation

A

usually autosomal recessive of X-linked

loss of activity of protein

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12
Q

gain of function mutation

A

overexpression or new function of protein

usually autosomal dominant

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13
Q

examples gain of function mutation disease

A

Charcot- Marie-Tooth

achrondroplasia

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14
Q

de novo mutation

A

new mutation not present in parents

accounts for significant genetic diseases

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15
Q

describe features of X linked inheritance

A

male dominant disease
unaffected ort mildly affected females
carrier status for 50% female progeny

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16
Q

describe the features of X-linked adrenoleukodystrophy

A

1/17,000
accumulation of very long chain fatty acids (VLCFA)
defect in ABCD1 on Xp28
adrenal dysfunction
neurologic symptoms such as seizures predict prognosis

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17
Q

treatment of X-linked adrenoleukodystrophy

A

bone marrow transplantation
Lorenzo’s Oil
-binds enzymes where VLCFA typically bind and clear them

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18
Q

describe features mitochondrial inheritance

A

maternal inheritance
all maternal offspring affected
impaired energy metabolism
liver, brain, muscle and heart

19
Q

examples of mitochondrial diseases

A

MERRF

Kearns-Sayre Syndrome

20
Q

describe genetic imprinting inheritance

A

some genes deactivated by methylation (epigenetics)

equal female and male offspring affected

21
Q

Prader-Willi Syndrome

A

paternal 15q13.3
maternal silence
obesity, short stature, hypogonadism, mental retardation, birth hypotonia

22
Q

Angelman Syndrome

A

maternal 15q13.3
paternal silence
ataxia, epilepsy, uncontrolled laughter, mental retardation

23
Q

what is a syndrome?

A

multiple, anatomically unrelated defects from a common cause

some defects may not be obvious so screening may be needed

24
Q

disorders associated with trisomy 21/ downs syndrome

A 
AV canal defect and other heart defects
duodenal atresia
hirschsprung disease
atlantoaxial instability
obstructive sleep apnea
early alzheimers
vision difficulties
hypothyroidism
leukemia
25
Q

surveillance recommendations for downs syndrome patients

A 
hearing every 6 mo until 5 yo
optho every 2 years after 6 mo
birth, yearly TSH
CBC every 3 mo until 3 yo, then every 6 mo until 6 yo
celiac at 1 yo
echo at birth
sleep study before 4 yo
26
Q

what is an association

A

pattern of defect without a known genetic or environmental cause
some defects may not be obvious so screening may be needed

27
Q

VACTERL

A 
association
vertebral anomalies
anal atresia
trachea-esophageal fistula
renal abnormalities
limb anomalies
28
Q

what is a sequence

A

one anomaly leads to other defect

29
Q

example of a sequence

A

Pierre Robin Sequence- micrognathia (small jaw) changes tongue position causing airway obstruction and cleft palate

30
Q

what are some important things to keep in mind when initiating genetic testing?

A

follow index of suspicion
sequential
consider costs
aggregate outside evaluation

31
Q

types of genetic testing

A

single gene analysis
genotyping
gene panel
genome sequencing
microarrays/ comparative genomic hybridization
Fluorescence in-situ hybridization (FISH)
high-resolution chromosome analysis

32
Q

single gene analysis

A

various mutations of gene coding regions
-specific mutation (factor 5 leiden)
-panel of common variants (CFTR, CF)
usually by PCR

33
Q

what can high resolution chromosome analysis detect

A

chromosome abnormalities 1-2% live births, 50% early fetal losses
identify unisomy, trisomy, and translocations
identifies large deletions, translocations, nondisjunction on all or part of the chromosome
deletions > 5,000

34
Q

how is high resolution chromosome analysis done

A

pre-natal: amniotic fluid, chorionic villus tissue

post-natal: peripheral lymphocytes, sometimes fibroblasts

35
Q

describe the process of comparative genomic hybridization

A

bind patient DNA (green) and reference DNA (red) to microarray grid
patient DNA amplification appears green
absence of patient DNA is red
equal patient and reference DNA is yellow
examine multiple gene and genetic regions simultaneously

36
Q

describe FISH

A 
higher resolution than chromosome analysis 
use fluorescent tagged sequence/ probe
-control probe
-identification probe
detect 50-200 kb deletion
limited to one disease
37
Q

candidate diseases for newborn screen have:

A
  1. significant morbidity and mortality
  2. improved outcomes with early treatment
  3. available testing
38
Q

how do newborn screenings work

A

obtained at 24 h of life
available in 7-10 days
sensitive but not specific, require follow up testing

39
Q

top 5 abnormalities for newborn screening

A
  1. hearing loss
  2. hypothyroidism
  3. cystic fibrosis
  4. sickle cell disease
  5. medium change acyl-CoA dehydrogenase deficiency
40
Q

technologies for newborn screening

A

Guthrie test
radioimmunoassay for thyroxine
liquid chromatography for hemoglobinopathies
tandem mass spectrometry for inborn errors of metabolism (organic acids, amino acids, fatty acids, and lysosomal storage disorders)

41
Q

commonly screened diseases in newborns

A 
congenital hypothyroidism
congenital adrenal hyperplasia
hemoglobinopathies (sickle cell disease)
cystic fibrosis
galactosemia
SCID
PKU
maple syrup disease
cyanotic heart disease
42
Q

challenges/concerns with newborn screening

A

residual blood specimens
role of late onset disease
carrier mutation

43
Q

indications for genetic counseling

A 
advanced parental age
previous child with fam history of issues
adult onset disease
consanguinity
teratogen
repeated pregnancy loss of infertility
abnormal pregnancy  screen
heterozygote screening by ethnic risk

IBI Test 4 (21 decks)

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