BP Chapter 3 Flashcards
What is mutated in CF?
Cystic Fibrosis Transmembrane Regulator
sx: chronic lung dx, cor pulmonale, pancreatic insufficiency
Two MC mutations in CF?
delta F508, G542X
What is the problem in sickle cell? who do you screen?
single point mutation in the gene for beta chain of Hb –> Hb S forms polymers when deoxygenated
test all persons of African descent
What is wrong in Tay Sachs?
def of hexosamindase A –> accumulation of gangliosides in the lysosomes –> neuronal death
What are the sx of Tay Sachs?
startle respnose, increased response to sound –> neuro degeneration, developmental delay –> seizures –> paralysis, blindness, dementia, –> death by age 4
What do heterozygotes’ MCV look like with beta thalassemia?
low MCV, mild hemolytic anemia
often Mediterranean or Asian or African descent
impairment of beta chain production –> excess of alpha chains
What Hb is seen in alpha thalassemia causing fetal hydrops?
no HbF, no HbA, and nearly 100% Hbalpha4
babies are born premature, are pale, hydropic, severely anemia, and have splenomegaly
____ is the only way to have a def dx of aneuploidy.
feta karyotype
What is included in a first trimester screen? second trimester?
- nuchal translucency, pregnancy-associated plasma protein A (PAPPA-A), and beta HCG
- Quad: MSAFP, beta HCG, estriol, inhibin
What abnormalities are associated with Down syndrome?
cardiac defects, duodenal atresia or stenosis, short limbs
classic facies, developmental delay, mental retardation, short stature
first trimester screen: 82-87% sensitivity
second trimester screen: 80% sensitivity
combined: 95% sensitivity
What are the US findings for Trisomy 18?
clenched fists, rocker bottom feet, overlapping digits , cardiac defects, omphalocele, congenital diaphragmatic hernia, neural tube defects, choroid plexus cysts
What problems go along with Trisomy 13?
holoprosencephaly, cleft lip and palate, cystic hygroma, single nostril or absent nose, omphalocele, cardiac anomalies including hypoplastic left heart, and limb anomalies including clubfoot and clubhand, polydactyly, and overlapping fingers
What is the only anomaly seen in US for Turners?
cystic hygroma
What does endoderm, mesoderm, and ectoderm form?
endodermal layer - gastrointestinal, respiratory
mesoderm - cardiovascular, musculoskeletal, and genitourinary
ectoderm - nervous system, skin, and many sensory organs
What mutation may predispose to NT defects?
homozygosity for a common mutation in the gene for methyl tetrahydrofolate reductase (MTHFR), the C677T allelic variant that encodes an enzyme with reduced activity.
When are NT defects done?
day 22-27
What US findings indicate Spina Bifida?
‘lemon’ sign (concave frontal bones)
‘banana’ sign (cerebellum pulled casually and flattened)
ventriculomegaly
clubfeet
What is the problem in Potter Syndrome?
b/l renal agenesis or renal failure (ex. distal outlet obstruction) leading to anhydramnios, which in turn causes pulmonary hypoplasia and contractures or deformations of the limbs in the fetus.
What are the three kidney stages?
pronephros - nonfunctional
week 5, the mesonephros develops and functions briefly, creating the mesonephric duct (Wolffian duct). The ureteric bud is an offshoot of the mesonephric duct that dilates and subdivides to form the urinary collecting system
mesonephric duct in males forms vas deferens, epididymis, ejaculatory duct, and seminal vesicles. In females, it degenerates entirely except for the vestigial Gartner’s duct
metanephros—week 5 of gestation and becomes the functioning kidney by week 9 of gestation. The ureteric bud from the mesonephric duct contacts the metanephros and induces it to form nephrons. If this contact does not occur, renal agenesis results.
When is an amniocentesis performed?
beyond 15 weeks; when the amnion and chorion have fused
obtains a fetal karyotype
risks: rupture of membranes, preterm labor, fetal injury, miscarriage
When can chorionic villus sampling be done?
weeks 9-12 to obtain a fetal karyotype
catheter into intrauterine cavity and aspirating a small quantity of chorionic villi from the placenta
risks more then amnio, but same risks
What is PUBS?
percutaneous umbilical blood sampling
determines fetal hematocrit and platelet count
