- a condition that can be tracked through a family - family hx may predispose you to them

QUIZ 5 Flashcards by Dorothy Cam

inherited conditions

a condition that can be tracked through a family

- family hx may predispose you to them

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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)

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genetic components

conditions that are affected by genetic changes (e.g. mutations, deletions, etc) that are not related to family hx/are new onset

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When should pts be referred to genetic counseling?

1) family hx
2) delayed growth and development
3) reproductive issues

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What is the cause of birth defects?

most unknown

Complex mix of:

1) genetics
2) behaviors
3) environmental factors

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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)

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Define spina bifida

neural tube defect in which spine and spinal column abnormally form –> spinal cord and nerves exposed through opening in back

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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)

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True or false: the higher the defect in spina bifida, the more severe the condition

true

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True or false: the majority of spina bifida cases are inherited

false; is multifactorial

Familial, but no apparent pattern of inheritance

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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

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What is the goal of carrier screening?

identify individuals at risk to have offspring w/ genetic disease

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What carrier screens are offered to all patients?

1) cystic fibrosis

2) spinal muscular atrophy

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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)

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Define aneuploidy

changes in numbers of chromosomes

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Define trisomy

one extra copy of a single chromosome

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Define monosomy

one missing copy of a single chromosome

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Define triploidy

three copies of every chromosome

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What is the most common genetic cause of miscarriage and birth defects?

aneuploidy

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Which of the types of aneuploidy have an age-related risk?

trisomies

risk for trisomy increases w/ maternal age

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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

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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

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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

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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