QUIZ 5 Flashcards
inherited conditions
- a condition that can be tracked through a family
- family hx may predispose you to them
What are the types of inherited conditions?
1) Mendelian patterns (e.g. cystic fibrosis, Tay Sachs)
2) multifactorial (e.g. addiction, Alzheimer’s, schizophrenia, autism)
3) multigenic (e.g. red hair, freckles)
genetic components
conditions that are affected by genetic changes (e.g. mutations, deletions, etc) that are not related to family hx/are new onset
When should pts be referred to genetic counseling?
1) family hx
2) delayed growth and development
3) reproductive issues
What is the cause of birth defects?
most unknown
Complex mix of:
1) genetics
2) behaviors
3) environmental factors
What are risk factors for birth defects?
1) smoking, EtOH, recreational drugs during pregnancy
2) maternal medical conditions (e.g. GDM)
3) medications (e.g. isotretinoin)
4) family hx of birth defects
5) AMA (>35yo)
Define spina bifida
neural tube defect in which spine and spinal column abnormally form –> spinal cord and nerves exposed through opening in back
What are associated sx of spina bifida?
- bladder and bowel problems
- sexual dysfunction
- weakness and loss of sensation below level of defect
- inability to move lower legs
- cognitive defects
- orthopedic malformations (e.g. club feet, knee/hip problems)
True or false: the higher the defect in spina bifida, the more severe the condition
true
True or false: the majority of spina bifida cases are inherited
false; is multifactorial
Familial, but no apparent pattern of inheritance
What are maternal risk factors for spina bifida?
- lack of folic acid supplementation
- maternal fever (>102º) or exposure to sauna/jacuzzi in first trimester
- diabetes
- medication exposure
What is the goal of carrier screening?
identify individuals at risk to have offspring w/ genetic disease
What carrier screens are offered to all patients?
1) cystic fibrosis
2) spinal muscular atrophy
What types of carrier screens should be offered to specific patients?
1) ethnicity-based screens
- hemoglobinopathies (African, Mediterranean, SE Asia)
- Ashkenazi Jewish diseases (ACOG: 4 disorders; ACMG: 9 disorders)
2) family hx/personal-based hx (e.g. fragile X)
Define aneuploidy
changes in numbers of chromosomes
Define trisomy
one extra copy of a single chromosome
Define monosomy
one missing copy of a single chromosome
Define triploidy
three copies of every chromosome
What is the most common genetic cause of miscarriage and birth defects?
aneuploidy
Which of the types of aneuploidy have an age-related risk?
trisomies
risk for trisomy increases w/ maternal age
What are associated birth defects of trisomy 13?
1) brain or spinal cord anomalies
2) small/poorly developed eyes (microphthalmia)
3) extra digits
4) congenital heart defects
5) cleft lip/palate
6) weak muscle tone (hypotonia)
7) severe intellectual disability
8) seizures
Of trisomies 13, 18, and 21, which has the best prognosis?
trisomy 21
trisomy 13 and 18 = POOR prognosis; many fetuses do not survive to term
What are associated birth defects of trisomy 18?
1) intrauterine growth retardation; low birth weight
2) small head w/ abnormal shape; small jaw and mouth
3) choroid plexus cysts
4) congenital heart defects
5) clenched hands w/ overlapping fingers
6) rocker bottom feet
7) failure to thrive
What is trisomy 21 most commonly known as?
Down Syndrome
What are the associated birth defects of trisomy 21?
1) congenital heart defects (seen in ~50%)
2) duodenal atresia
3) soft signs: absent/short nasal bone, enlarged kidneys, shortened long bones, fifth finger clinodactyly
4) characteristic facial features
What are associated medical conditions of trisomy 21?
1) GERD
2) Celiac disease
3) hypothyroidism
4) increased risk of hearing and vision problems
5) increased risk leukemia
6) increased risk Alzheimer disease
What are learning and behavior deficits people with trisomy 21 experience?
1) mild to moderate intellectual disability
2) delayed speech and language
3) attention problems, OCD, stubbornness, tantrums
4) Autism spectrum disorders
True or false: Down syndrome is hereditary and runs in families
false
T or F: risk of having child w/ Down syndrome increases w/ AMA
true
most children born w/ Down syndrome are born to women <35 yo
BUT
AMA increases risk
According to ACOG, to whom and when should aneuploidy screening be offered?
ALL pts before 20 wks
T or F: according to ACOG, invasive screening should only be offered to pts >35yo
false
screening or diagnostic?
Identifies a condition
diagnostic
*screening identifies risk
screening or diagnostic?
Casts a wide net to best identify true positives
screening - causes rates of false positives to increase
*diagnostic has low false positives
screening or diagnostic?
Typically, no risk to pregnancy
screening
*diagnostic have risk associated
screening or diagnostic?
Assesses broad set of conditions
diagnostic
*screening is limited: common trisomies, selected microdeltions/microduplications
What does maternal serum screening identify?
pregnant people who are at “high risk” of having baby w/ trisomies 13, 18, or 21 as well as NTD
How is maternal serum screening completed?
Combination of:
1) U/S (first-trimester screening)
2) maternal blood work
3) maternal demographics
What are the 4 types of maternal serum screenings?
1) first trimester screening
2) quad screen
3) sequential screen
4) integrated screen
When is the first trimester screen performed?
11.0-13.6 wks
What is required to perform the first trimester screen?
1) U/S for nuchal translucency
2) blood work
For what does the first trimester screen?
1) Down syndrome
2) trisomy 18
When is the quad screen performed?
15.0-21.6 wks
What is required to perform the quad screen?
blood work
For what does the quad screen?
1) Down syndrome
2) trisomy 18
3) open neural tube defects
Describe sequential screening
perform first trimester screening –>
1) high risk detected –> offer other testing (e.g. cell-free DNA, CVS, amniocentesis)
2) low risk –> collect 2nd trimester blood work –> give one overall risk estimate
What is required to perform a sequential screen?
1) U/S for nuchal translucency
2) blood work in 1st and 2nd trimesters
For what does the sequential screen?
1) Down syndrome
2) trisomy 18
3) open neural tube defects
Describe an integrated screen
Combines first trimester screen and quad screen –> gives one result in 2nd trimester
What is required to perform an integrated screen?
1) U/S for nuchal translucency
2) blood work in 1st and 2nd trimesters
For what does the integrated screen?
1) Down syndrome
2) trisomy 18
3) open NTDs
Define chorionic villus sampling (CVS)
diagnostic test that collects sample of placenta
When is CVS performed?
10.0-12.0 wks
Define amniocentesis
collection of amniotic fluid from around baby
When is amniocentesis performed?
after 15.0 wks
What is the most accurate way to get genetic information about baby before birth?
amniocentesis
Why are invasive diagnostic tests performed?
1) dx of genetic conditions
2) confirm infection in pregnancy
3) dx/confirmation of open NTD
4) fetal blood typing
5) understanding kidney function
What are the risks of invasive testing?
- infection –>
- miscarriage <25 wks
- PTB >25 wks
What are the advantages of invasive testing?
- > 99% accurate
- able to look for chromosomal abnormalities outside common aneuploidies
- can screen for single gene disorders
- can have testing done on panels cause a specific phenotype
