genetic counseling Flashcards
dysmorphology/morphogenesis
abnormal physical dev.
teratology`
study of environmental causes of congenital anomalies
what can malformation be due to?
chromosome abnormalities, single gene disorders, teratogens, multifactorial, pregnancies complications, unknown
the cause of ____ of congenital defects is unknown or multifactorial
2/3
a known genetic component of congenital defects is in about _____% of cases
30%
environmental causes for congenital anomalies are _______
infrequent
malformation?
primary defect of an organ or body part from an abnormal developmental process
malformation examples
spina bifida, polydactyly, cleft lip
dysplasia?
primary defect involving abnormal organization of cells into tissues
dysplasia examples?
port wein stains, hip dysplasia, pointy teeth
sequence
primary defect with secondary structural changes; basically one thing goes wrong which causes a cascade of other events to occur
sequence example
potter sequence
what is potter sequence
less amniotic fluid got to the fetus from renal disease/obstruction which caused clubbed feet, pulmonary hypoplasia, and cranial anomalies
syndrome?
pattern of multiple primary malformations with a single gene causing it; malformation are UNRELATED!!
syndrome example
down syndrome
deformation?
changes in the form, shape, or position of a normally formed body part from mechanical forces; this is a secondary alteration
deformation example
plagiocephaly, clubfoot
disruption?
defect of an organ, part of an organ, or larger region of the body because something interfered with development
disruption example
amniotic band
most important question to ask when evaluating a child with a congenital malformation
is the defect isolated or part of a syndrome
teratogens?
agents that cause birth defects when present in the environment of a developing fetus
these act directly and transiently on developing embryonic tissue
teratogens
are individual thresholds for teratogen effects predictible
NO
organs and parts of an embryo are most sensitive to teratogenic agents during periods of __________
rapid differentiation
3 principles to consider when there is a teratogenic exposure
critical period, dosage of drug/chemical, genotype of embryo
critical period?
when cell division, differentiation, and morphogenesis is at its peak
each tissue and organ has its ____ critical period
own
critical period for brain is ________ but continues _____ after birth
3-16 wks gestation; 2 yrs
_____ and _____ dev. also continues after birth
tooth and skeletal
if a teratogen is exposed in the first 2 wks of pregnancy, what occurs?
it interferes with cleavage and implantation a miscarriage will occur
if a teratogen is exposed during 3-8 wks of pregnancy, what occurs?
major congenital anomalies and functional defects
if a teratogen is exposed during 9-38 wks of pregnancy, what occurs?
functional defects and minor anomalies
one of the most severe outcomes of alcohol use during pregnancy
fetal alcohol spectrum disorder (FASD)
FASD?
physical, behavioral, and cognitive abnormalities due to alcohol intake during pregnancy
cardinal facial features of FASD
small palpebral fissures, smooth philtrum, thin upper lip
hallmark feature of FASD
smooth philtrum
what disorder has a “railroad track ear”
FASD
effects of anti-epileptic drugs during pregnancy?
broad spectrum, but congenital heart disease, clefting, and NTD
the risk of antiepileptic drugs affecting pregnancy may vary due to this
dosage of the drug
valproate?
antiepileptic drug that can cause birth defects
fetal valproate syndrome sx
limb defects, heart defects, spina bifida, hypospadias, dec fetal growth, characteristic craniofacial appearance
these drugs can increase ones risk for a birth defect if taken during pregnancy
warfarin/coumadin, retinoic acid, valproate
if you take this drug while pregnant, the syndrome the baby may get is identical to a severe form of chondrodysplasia punctata
warfarin/coumadin
high perinatal and fetal loss, skeletal defects like nasohypoplasia and stippled epiphyses, CNS abnormalities, eye and hearing abnormalities, IUGR, congenital heart disease
manifestations of taking warfarin/coumadin while pregnant
microtia, conotruncal abnormalities, cardiac malformations, posterior fossa malformations, thymus and parathyroid malformations
retinoic acid
this drug causes abnormalities of neural crest and branchial arch derived structures
retinoic acid
what is retinoic acid used to treat
medication used to treat acne
this can prevent NTD like spina bifida and anencephaly
folic acid
how much folic acid should every woman of reproductive age take daily
400 mcg
NTD occur _____ gestation
14-28 days
genetic counseling was a term first coined by ______ in _____
Sheldon Reed in 1947
process of genetic counseling?
interpretation of family and medical hx, educate pt about inheritance, testing, management, prevention, and resources, counseling
prenatal, peds, cancer, cardiology, neurology, metabolic syndromes, specialty clinics, research, advocacy groups, labs
where genetic counselors work
what does Bayes theorem do
a way to identify the probability of an outcome by considering all initial possibilities then modifying it with other information; risk of getting a disease
prior probability?
baseline likelihood or having or not having a mutation
conditional probability?
probability of NOT developing a disease
joint probability?
probability of having a mutation AND not developing disease
if something is XLR, there is a ____% chance of being a carrier of the condition
50
what happens in a typical genetic counseling session?
collect FH and personal hx- educate and assess risk- discuss options for genetic testing and medical management- follow up
what do you need for an accurate dx of a genetic test
at least 3 generations on a pedigree, dx confirmed with medical records, multiple specialists to evaluate, understanding of variability, penetrance, and age of onset, familiarity with testing options, and understanding modes of inheritance
why might we see a negative FH in someone with a genetic disease?
de novo mutation, autosomal recessive, chromosome abnormality, variable expression, reduced penetrance, anticipation, sex linked traits, false paternity
what is the benefit for pt in nondirective genetic counseling
pt can make independent informed decisions without coersion
how is nondirective genetic counseling established
counselor sets goals, counselor provides info in unbiased manner, counselor does not give personal beliefs
when might genetic counselors be directive?
testing minors of adult onset conditions, unstable pt, encouraging pt to share results with family members, discussion about screening/management
what do we need to inform pts of before getting genetic testing
risks, related medical information, possible options, medical outcomes
7 steps in plan to full decision making
- identify decision to be made
- gather relevant info
- identify options
- weigh evidence
- choose among options
- take action
- review decision and its consequences
purpose of genetic counseling?
help individual or family:
- comprehend- dx
- appreciate- hereditary and risk of recurrence
- understand alternatives
- choose course of action
- make- good adjustment