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Master Boards Review -- Prenatal
Terms in this set (113)
Meaning of Gs and Ps
G = total # pregnancies. P = Term, Preterm, Abortions, Living
Embryonic period of pregnancy
5-10 weeks post LMP, 3-8 weeks of development. All major internal and external structures develop during this time.
When to change pregnancy due date and recalculate MSS results, and redraw for MSS
>1 week discrepancy in 1st trimester, >2 weeks discrepancy in 2nd trimester and >3 weeks discrepancy in 3rd trimester.
For Recalcs: in 2nd trimester if US indicates gestational age is incorrect by 10+ days, inform lab and recalculate (EXCEPT if fetus screens positive for T18). Use difference of 7 days for 1st trimester US.
Redraw: only if US indicated initial sample was drawn too early, or if screen is positive for ONTD and AFP is between 2.5 and 3.0 (do not repeat for increased DS risk!)
New onset of hypertension and proteinuria after 20 weeks gestation in a previously normotensive woman
Abbreviations for miscarriage, still birth
Stillbirth = SB. Spontaneous abortion = SAB. Termination of pregnancy = TOP. Triangle shape. Terminations have a line through them.
Gestational age spontaneous abortion, preterm, full term
SAB is 20 weeks or earlier. Preterm is after 20 weeks and before 37 weeks. Full term is 37 week or higher.
Aneuploidy associated with AMA
All autosomal trisomies, and XXX. XXY is roughly equal maternal vs. paternal origin with slightly increased risk for AMA. 45,X majority is paternal in origin. Triploidy does not appear to be associated w/ AMA.
Percent of people with 3 or more miscarriages that have a balanced translocation
De novo balanced rearrangement, risk for serious congenital anomaly
Estimated prevalence 1-3% of pregnancies at conception. 2/3 miscarry in first trimester.
Diandry: Normal egg is fertilized by a sperm w/ 2 sets of chromosomes, or egg fertilized by 2 sperm. 2 sets of paternal chromosomes, 1 set maternal. Tend to have large placenta, baby is normal size, but more likely to miscarry in frist trimester. US at 10-14 weeks shows small baby, large placenta, thick nuchal fold (not usually cystic hygroma). High AFP and hCG, low PAPP-A. Partial molar pregnancy -- reminants of mole tissue causes risk for choriocarcinoma, FU 6-24 months.
Digyny: Egg contains 2 sets of chromosomes because of failed division and fertilized by a single sperm. 2 sets of maternal chromosomes, 1 set of paternal. Small placenta and baby is usually severely growth restricted. More often die later in pregnancy (2nd trimester, occasionally to birth). US 10-14 weeks shows small placenta and very small baby. AFP low to normal, hCG and PAPP-A low.
Molar pregnancy: Empty egg w/ no chromosomes is fertilized by normal sperm that divids to create a diploid w/ all paternal chromosomes. No fetus, hyperplastic placenta. 10-15% risk for choriocarcinoma.
Ovarian teratoma: Benign tumor from meiosis, diploid all maternal chromosomes, no placenta and abnormal fetus.
For triplody, karyotype may be 69,XXX or 69,XXY (abnormal genitalia) or 69,XYY.
Aneuploidy incidence in sperm, oocytes and preimplantation embryos
Preimplantation embryos: 20%
Most common aneuploidy and incidence in SAB and stillbirth
SAB aneuploidy incidence is 35%, trisomy 16, 21, 22
Stillbirth aneuploidy incidence 4%, trisomy 13, 18, 21
Cystic Fibrosis, carrier rate, US finding
CFTR gene. 23 mutations account for 90% of all mutations individuals of European ancestry.
CBAVD in 98% of men w/ CF. >50% of men w/ CBAVD have at least 1 CF mutation.
Caucasian and AJ: 1/25. African american: 1/65. Hispanic: 1/46. Asian American: 1/90.
Incidence: 1 in 2500.
10-15% have meconium ileus. Fetus with echogenic bowel has 1-10% risk for CF
Recurrence risk for ONTD
One child: 4%, 2nd degree relative: 1.7%
Condition with high carrier rate in AJ and French Canadian/Cajun
Tay-sachs: 1 in 25 carrier rate for AJ, 1 in 50 for French Canadian and Cajun (general population 1/300 carrier rate)
Conditions with high carrier rate in African-Americans
Sickle Cell: 1/12. Alpha-thalassemia: 1/30. Beta-thalassemia: 1/50-75. Hemoglobin C disease: 1/50.
Condition with high carrier rate in Italian/Mediterranean
Condition with high carrier rate in Southeast Asia
Condition with high carrier rate in Pennsylvania Duth/ Mennonite
Incidence of ONTD, T21 and T18 overall
ONTD: 1/1400 in Utah or 1-2/1000 in US. T21: 1/600-700 live births. T18: 1/5000 live births
Only useful in 2nd trimester. ONTD is high, DS and T18 is low
DS: high in both 1st and 2nd trimesters. T18: Low-normal in 1st trimester and low in 2nd trimester. Stronger predictive power with DS.
Lower in 2nd trimester for DS and T18. Strongest 2nd trimester marker for T18
Higher in 2nd trimester for DS. Not used in calculation of T18
Only useful in 1st trimester. DS is low, T18 is very low
NT gestational age and thickness
US between 10w3d - 13w6d. Width 0.8-1.5
Variables affecting MS markers
Gestation, weight, race, diabetes, twins
14w0d - 24w6d. AFP, hCG, uE3 and DIA
Quad screen patterns for birth defects:
L/H/L/H is Down syndrome or overestimated gestation;
L/L/L/- Trisomy 18;
H/N/N/N ONTD, maternal-fetal hemorrhage, VWD;
VH/N/L/N Anencephaly, fetal demise;
N/N/L/N X-linked ichthyosis, Smith-Lemi-Opitz
H/H/H/H Multiple fetuses
H/L/H/N normal, underestimated gestation
VL/H/VL/N mole or partial mole
Increased NT measurement follow-up
If NT 3.5mm or higher: pt is at high risk for fetal aneuploidy, additional serum screening is not indicated. Offer genetic counseling and either NIPT or CVS/amnio, and targeted ultrasound and fetal echocardiogram in the second trimester, even if the screening results suggest low risk for aneuploidy.
FU for No US anomaly, but MSAFP OR hCG is elevated
MSAFP MoM >3.0: may confirm w/ amniotic fluid tests (amniotic fluid AFP w/ reflex to acetylcholinesterase and fetal hemoglobin), chromosome analysis. If all FU testing is normal, pt is at increased risk for poor pregnancy outcome (prematurity, SGA, stillbirth)
hCG >3.5: pt is at increased risk for poor pregnancy outcome (preeclampsia, imminent fetal death, SGA)
First trimester screen
11w0d - 13w6d. Markers: PAPP-A and total hCG, also NT measurement. Have AFP drawn in 2nd trimester for NTD screen.
10w0d - 13w6d AND 15w0d - 22w6d. 1st trimester: PAPP-A and NT. 2nd trimester: AFP, hCG, uE3, DIA.
10w0d - 13w6d AND 15w0d - 22w6d (recommend 11w3d instead of 10w0d because of hCG). 1st trimester: PAPP-A, hCG and NT. 2nd trimester: AFP, hCG, uE3 and DIA.
Cystic hygroma, risk for genetic condition
50% risk for aneuploidy. 2/3 Turner syndrome, 1/3 Down syndrome. High rate of adverse outcome. About 1-4% of cases with normal karyotype are Noonan syndrome
common reasons for elevated AFP
25% incorrect gestational dating, 10% twins, 5% fetal demise, 1% neural tube defect, <1% ventral wall defect / oligohydramnios
Gestational date to detect ONTD
16-18 weeks at experienced centers will detect 95%
Limit of resolution for standard karyotyping, FISH, microarray
Karyotype 5-10 MB. FISH for clinical use most probes 100-500kb. Microarray resolution depends on density of clones, can be as good as <10Kb
Common abbreviations for Karyotype results
add additional material on chromosome, unknown origin
der derivative chromosome, due to rearrangements
mar marker chromosome, unknown origin
r ring chromosome
College and Society for MFM recommendations for microarray for prenatal dx
Fetus w/ 1+ major structural abnormalities on US undergoing invasive prenatal dx: microarray is recommended and replaces need for karyotype
Structurally normal fetus undergoing invasive prenatal dx testing, fetal karyotyping or chromosomal microarray can be performed.
The use of microarray for prenatal dx should not be restricted to AMA women.
Fetal tissue microarray is recommended for 3rd trimester pregnancy loss, not 1st or 2nd trimester.
US detection of Down syndrome and T18
2/3 of DS cases have no detecctable major anomaly. 80-90% of T18 cases have detectable anomaly
AR syndrome, deficiency in cholesterol metabolism. Carrier rate 1/30 - 130, highest in Caucasian. Prevalence 1:25,000. High lethality in infants. Prenatal and postnatal growth retardation, microcephaly, moderate to severe ID, multiple major/minor malformations, CHD (septal defects, TOF, complete AVSD with TAPVR). Deficiency of 7-dehydrocholesterol (7-DHC) reductase, gene DHCR7. 96% of mutations detected by sequence analysis.
T21 US markers
Absent nasal bone in 60-70% (LR 35), flat face. Major markers 2nd trimester: CHD (AVSD, VSD, tetralogy), GI anomalies (duodenal/esophageal atresia), CNS (mild ventriculomegaly). Minor markers 2nd trimester: nuchal thickening (LR 11 if isolated, 55 if other markers seen), short femur (1.5) /humerus (5.5), echogenic bowel (bright as bone 6.7), intracardiac echogenic focus (1.8), pelviectasis (1.6), absent nasal bone (9), clinodactyly, sandal gap toe. Multiply LR if you see more than one, then multiply by a priori risk. Normal US, reduce risk 0.5 for T21
Abnormal ductus venosus
aneuploidy 65-90%. Increased risk of poor outcome even if chromosomes are normal. Increased risk for twin twin transfusion.
Soft markers for aneuploidy
Choroid plexus cysts (T18), echogenic cardiac focus (LR is <2), single umbilical artery (if not isolated T13 or T18), renal pelviectasis (T21, seen in 3% of normal fetuses), mild cerebral ventriculomegaly (mostly T21, 4% aneuploidy, 90% idiopathic), echogenic bowel (1-2% T21, 1-2% in-utero infection, 0-33% CF, 1-2% bowel pathology).
T18 US markers
Growth restriction, complex CHD (VSD most common), omphalocele, facial cleft, arthrogryposis, abnormal hands/feet
T13 US markers
Significant brain/facial malformations, holoprosencephaly, polydactyly, renal disease
Turner syndrome US markers
Cystic hygroma, shortened long bones, LV outflow obstruction, horseshoe kidney
Cornelia de lange US markers
Diaphragmatic hernia, limb reduction, typical faces
Meckel Gruber US markers
Encephalocele, cystic renal disease, polydactyly
US findings associated with T18
Strawberry shaped head, choroid plexus cysts
Single flextion crease, clinodactyly, transverse plamar crease
Most common lung masses
Congenital pulmonary airway malformation (CPAM), pulmonary sequestration. Also CDH (stomach), bronchogenic cysts, neurenteric and enteric cysts, teratomas
CDH associated anomalies
>30% have associated anomalies. Fryns (genetic etiology unknown, AR inheritance), Pallister-Killian (mosaic supernumary isochromosome 12p), aneuploidy, Cornelia de Lange
ONTD an folic acid
Women should take 400 mcg of folic acid daily (4000mcg / 4mg if prev pregnancy). Decrease recurrenc of NTD by up to 70%.
When does neural tube close
26-28 days development
Amnio for ONTD
With US findings, it is not needed for diagnosis. Will have increased AFaFP and acetylcholinesterase. 5% of fetuses w/ aparently isolated spina bifida have abnormal karyotype.
US findings associated with ONTD
Lemon sign: frontal bone scalloping, 90% of fetuses at <24 weeks. Banana sign: Arnold Chiari II common with myelomenigocele, brain stem and hindbrain protrude downward into the spinal canal or neck area. Complications of Chiari II: compression of spinal cord causing difficulties feeding, swallowing, breathing control, changes in upper arm function, blockage of cerebralspinal fluid resulting in hydrocephalus, may develop meningitis. Obliteration of posterior fossa, 95% of fetuses. Ventriculomegaly: 75% of fetuses. Club foot. US diagnostic accuracy is 80-90% overall. Also associated w/ hydrocephalus.
Common features: paralysis of lower limbs, loss of bowel/bladder control, cerebral ventriculomegaly requiring shunt placement
Occulta: skin covers opening in vertebrae, present in 10-20% of GP and rarely causes sx.
Meningocele: no nerve damage, spinal cord is not in sac, minor disabilities.
Myelomeningocele: most common, sac contains spinal cord and nerves, major disabilities.
Anencephaly: Assoc amniotic bands, T13, T18. 50% of infants are stillborn, remainder die w/in hours or days of birth.
Exencephaly: absent bones of the cranial vault with residual brain tissue
Encephalocele: Herniation of cranial contents through a defect in the skull. High association with chromosome abnormalities (13, 18, mosaic 20) and single gene conditions (AR)
Iniencephaly: Deficiency of occipital bone, cervicothoracic spinal retroflexion, rachischisis
Risk factors: diabetes, obesity, overheating, medications (depakote), NOT maternal age.
Type of CVS based on gestational age
10-13 weeks LMP transcervical or transabdominal, 13+ weeks transabdominal.
Frequency of mosaicism in CVS and amnio
1-2% of CVS samples, 0.1-0.3% of amnio samples
Onset of Alpha and Beta Thalassemia
Alpha is in utero, beta is after birth
Types of Alpha Thalassemia
Alpha (+) silent carrier (-a/aa).
Alpha (0) thal trait (--/aa) or (-a/-a) cis or trans
Hemoglobin H disease (--/-a).
Barts- hydrops fetalis (--/--).
Alpha globin. Carrier freq: 1:40 mediterranean, 1:20 asian, 1:3 silent carrier african american. (4 copies of alpha globin gene, 2 on each chromosome). 90% of mutations result from 7 large deletions.
Embryonic, fetal and adult hemoglobin
Ebryonic: zeta-epsilon, zeta-gamma and alpha epsilon. Fetal: alpha-gamma. Adult: alpha-beta (primarily), alpha-gamma, alpha-delta.
At risk populations for beta thalassemia trait
Mediteranean countries, middle east, southern asia, former soviet bloc.
At risk populations for alpha thalassemia trait Cis and Trans
CIS: East/Southeast asia (China, Thailand, Vietnam, Malaysia). TRANS: Southern Europe, Middle East, Africa, Southern Asia, Oceania
Cause and Symptoms of Sickle Cell Disease
Caused by a single mutation of beta-globin gene.
Disease is HbSS
Coinheritance w/ other abnormal beta-globin
Most common HbC, causes sickle-hemoglobin C disease (HbSC)
Beta-thal mutation (B+ is some beta, B0 is no beta chain)
Capillary blockage leads to infarcts of bone, spleen and lungs. Immune system compromised (bacterial infections). Chronic anemia characterized by destruction of RBC and episodic blocking of blood vessels by adherence of sickle cells, splenomegaly. Skeletal abnormalities result from two alterations in the bone marrow: hyperplasia and infarction Pain crises, heart & kidney failure. Tissue hypoxia cause acute and chronic damage
Hemoglobin E cause and symptoms
Single mutation in beta-globin gene. Carriers are asymptomatic, common in Southeast Asian. Mild hemolytic anemia and mild splenomegaly.
mean corpuscular volume. MCV is low for carriers of Thalassemia trait.
Differentiating iron deficiency and Thalssemia minor (minor = trait)
Iron deficiency has low MCV, MCH, serum iron, serum ferritin, hemoglobin A2 and hematocrit. Thalassemia minor has low MCV and MCH, and normal serum iron and ferritin, and high hemoglobin A2, normal hematocrit
Herniated organs protrude through umbilicus into membranous sac. Typically contains bowel, stomach or liver. T13, T18, T21 have increased risk for omphalocele, T18 is highest. Associated with BWS. May have elevated maternal serum AFP (less often than gastroschesis). Risk for associated anomalies or chromosomal condition >50%. 18-24% risk for cardiac defects.
Internal organs protrude through an opening in the abdominal wall. Typically hole is to the right side of umbilical cord. Risk factors: smoking, maternal age, exposure to drugs, infection. Elevated AFP.
Failure of developing brain to completely split into left and right cerebral hemispheres. US will diagnose most alobar and semilibar. Associated findings: facial anomalies in 80% (cleft lip/palate, malformed eyes/nose, single central incisor, hypotelorism), microcephaly, ventriculomegaly, hydrocephalus. Clinical findings: developmental delay, seizures, feeding difficulties, failure to thrive. 25-50% have chromosomal abnormality. 10-20% have CNV detectable by microarray. 18-25% have single gene mutation (Pallister-Hall, Rubinstein-Taybi, Kallmann)
Alobar: most severe, monoventricle, associated w/ midline clefts.
Semilobar: intermediate form, partial separation in posterior, anterior fusion of frontal/prietal lobes.
Lobar: Separate cerebral hemispheres, fused fornices, midline fusion/anomalies. Middle interhemispheric fusion variant: most mild, posterior frontal and parietal lobes fail to separate
Risk for offspring of consanguious couples
First cousins have 2-3% increased risk for birth defects in offspring.
First degree relatives may be 7-12% risk above background (theoretical) for birth defect in live-born child. About 30% risk for severe birth defect or death.
Cleft lip and palate
Incidence 1/700. 50% cl/p, 20% lip alone, 30% cleft alone. 30% are syndromic. Risk factors: smoking, diabetes, certain medications.
AJ Jewish conditions
Gaucher Type I (1:15), Tay-Sachs (1:25), CF (1:25), Familial dysautonomia (1:30), Canavan (1:40), Niemann-Pick A (1:80), Fanconi anemia C (1:89), Bloom syndrome (1:110), Mucolipidosis IV (1:122), Torsion dystonia (1:900)
Neurodegenerative disorder of variable severity. Caused by absent or near absent hexosaminidase A. Lysosomal storage disorder. Infantile form presents at 3-6 months. Loss of motor skills, feeding difficulties, seizures, blindness, deafness, death by 5 years. Late onset: adolescence to mid-30s, difficulty walking/jumping, clumsiness, slurred speech, balance problems, mental/behavioral involvement. Carrier screening is enzyme assay for Hex A followed by molecular testing. Gene HEXA
Insensitivity to pain, temp, taste. Inability to produce overflow tears, unstable blood pressure, severe eye problems, poor growth, scoliosis, excessive sweating, GI problems, mean age of death 30 years. Carrier frequency 1/30 in AJ. IK-BKAP gene
CNS demyelinating disorder. Deficiency of aspartoacylas enzyme. Dev delay starts at 5-8 months, deterioration of motor skills, vision, mental function, enlarged head, feeding difficulties, death in childhood. Carrier freq 1/40 in AJ. Gene ASPA.
Niemann-Pick Disease (Type A)
Dev delay, blindness, progressive spasticity, feeding difficulties, recurrent vomiting, enlarged liver and spleen, death by 2-3 years. Carrier frequency 1/80 in AJ. Gene SMPD1.
Fanconi Anemia (Type C)
Short stature, bleeding and bruising, increased risk for cancer, death by young adulthood. Carrier freq 1/89 in AJ. Gene FANCC
Bloom syndrome carrier freq in AJ
Carrier freq 1/110 in AJ. BLM gene
Mucolipidosis type IV carrier freq AJ
Carrier freq 1/122 among AJ. Gene MCOLN1
Onset age 6-16 years. Difficulty walking, rigid limbs, twisting muscle spasms. Carrier freq 1/900 in AJ
SMA carrier rate
Carrier frequency 1/40 - 1/60, may be as high as 1/35 among Caucasians.
Prevalence of miscarriage
10-15% of recognized pregnancies end in miscarriage, majority in 1st trimester.
Up to 9w0d medical abortion, Mifepristone and Misoprostol. Up to 12w6d D&C (suction and aspiration, could be upt to 13-14 weeks). 13w - 22w6d D&E, limiting factor is cranial size and calicification, cannot be performed after about 22-23 weeks. 23w0d induction.
ACOG conditions for testing AJ carrier screening
Cystic fibrosis, Canavan, Familial dysautonomia, Tay Sachs
Valproic acid (Depakote)
Seizure medication. 1-2% risk for ONTD if taken 17-30 days post conception.
Increased risk for heart defect and cleft lip.
Fetal valproate syndrome: facial dysmorphism limb and heart effects, MR, IUGR
Risk is greater w/ higher does and multiple seizure meds. Increased risk for behavior and learning problems.
Retinoic acid (Accutane)
Taken orally. 35% rate of major malformations: small/absent ears, hearing/vision problems, small jaw/head, missing thymus, conotruncal heart defects, cranial nerve palsies, absence of vermis of cerebellum.
Higher rate of ID.
40% risk SAB if taken early in pregnancy.
Cream: Retin-A applied topically is not teratogenic.
Warfarin (Coumadin) and related anticoagulants
Greatest sensitivity weeks 4-7 development.
15-20% risk for Fetal warfarin syndrome: skeletal defects, nasal hypoplasia and epiphyses, limb hypoplasia, choanal atresia, nervous system and ophthalmis anomalies, hearing loss, IUGR, CHD.
Recommendation: substitute w/ heparin
Methotrexate / Aminopterin
Greatest sensitivity weeks 6-8 development. Stops the growth of cells and intereferes w/ immune system -- used to treat cancer and autoimmune diseases. Malformations of head, face and bones, poor growth and developmental delay, normal intelligence
Phenytoin / hydantoin (Dilantin)
Anti-convulsant. If taken in 1st trimester, 10% risk for fetal hydantoin syndrome and 33% of at least one birth defect. Growth deficiency, dev delay, cleft palate, facial features, CHD, GU abnormalities, abnormal fingers/nails.
Possible increased risk for heart defects. Withdrawl symptoms in babies for the first few days of life. Celexa (citalopram), Lexapro (escitalopram), Luvox (fluvoxamine), Paxil (paroxetine), Prozac (fluoxetine), Zoloft (sertraline)
MMF (mycophenolate mofetil)
Immunosupressant used in organ transplantation and in lupus/RA. Cleft lip/palate, microtia / aural atresia, bilateral micropthalmia / colobomas. Some evidence of CHD and CDH
Associated with a slightly increased risk for heart defects (1-5%).
Increased risk for Ebstein's anomaly (heart defect).
May increase risk for cleft palate, NTD, skeletal defects. Increased risk for goiter in mom, which can cause goiter in baby if untreated
Exposure in last month gestation: toxic effect on thyroid, kidneys, neuromuscular. Floppy baby for 1-2 weeks.
Taken after the 4th months of pregnancy there is a risk for discoloration of the "baby" teeth. It appears to affect the calcification of bones and teeth and reduce growth of some bones, which returns to nomal after exposure ends.
Babies born to mothers w/ untreated PKU: microcephaly, ID, behavior problems, facial features similar to FAS, higher risk for heart defects.
Most common teratogen.
Risk correlates to HgbA1c levels:
>10 is 23.5%
8.9-9.9 is 8.1%
<7.9 is 3.2%.
Most common birth defects:
Cardiac: transposition of great vessels, VSD, situs inversus, single ventricle, HPLV
CNS: anencephaly, encephalocele, meningomyeolocele, spina bifida, holoprosencephaly
Musculoskeletal: caudal regression, club foot, cleft palate
GU: renal agenesis, multicystic dysplasia, hydronephrosis
GI: pyloric stenosis, duodenal atresia, rectal atresia, small left colon
Increased birth weight, nerve damage to the shoulder during delivery, low blood sugar after birth, increased risk for obesity later in life.
Treatment of hyeprtension and congestive heart failure. Fetopathy with exposure in 2nd and 3rd trimesters: renal dysplasia, renal failure, oligohydramnios, hypoplastic calvaria, IUGR. Exposure in 1st trimester: CHD and ONTD. Examples: captopril, enalapril, peridopril, lisinopril, imidapril, cilazapril.
Treatment of seizures. 1% risk for ONTD. Other birth defects: small nose, wide philtrum, small finger nails. 2-3X risk for major defects: cleft lip and CHD, growth retardation, microcephaly.
Carbimazole / methimazole
Treatment of hyerthyroidism. Congenital scalp defects. Other birth defects: choanal atresia, omphalocele, esophageal atresia, hearing loss, facial features.
Heavy metal chelating agent used to treat Wilson's disease, RA, cystinuria. Possibly associated with connective tissue disorders such as lax skin, flexible joints, poor wound healing and inguinal hernia.
Trimethadione (Tridione) / paramethadione (Paradione)
Treatment of epilepsy. Fetal trimethadione syndrome: dev delay, ID, low-set ears, plate and cardiac defects, irregular teeth, V-shaped eyebrows, speech disturbances.
Antifungal used for vaginal candidiasis. High doses over long periods of time increased risk for birth defects. Major malformations of head, face, bones and heart.
10-30% of fertilized eggs have chromosome abnormality.
Aneuploidy is leading known cause of pregnancy loss >25% of all miscarriages. 20-25% of oocytes are aneuploid and 1-2% of sperm.
Chromosomes with a phenotype for UPD
Maternal UPD 7: Russell-Silver
patUPD 11: BWS
matUPD14: mild-moderate developmental delay, short stature, precocious puberty, scoliosis
patUPD14: Polyhydramnios, low birth weight, blepharophimosis/ short palpebral fissures, small ears, small thorax, abnormal ribs, joint contractures, severe mental retardation
patUPD15: Angelman syndrome
Most common Robertsonian is der(13;14)(q10;q10).
For Roberstonians identified in normal individuals, risk of UPD is <1% for non-homologous chr and 66-73% if it involves homologous chromosomes.
ACMG recommends UPD testing when fetus is identified w/ Robersonian involving UPD14 or 15
Steroid sulfatase deficiency. 90% of mutations are deletions of the STS gene. Scaley skin in males, female carriers occasionally report dry, itchy skin.
Etiology of Aneuploidy
>80% of aneuploidies originate in oogenesis.
Overall, aneuploidy results from meiosis I errors more often than meiosis II errors.
Paternal age does not play a significant role.
Monosomy X originates 80% of the time from paternal origin
Timing of Teratogens
All or none period (4 weeks from LMP): conception to implantation
Embryonic period (4-10wk from LMP): maximum exposure risk
Fetal Period (after 10 week by LMP): Growth and functional maturation of organs and systems can result in Fetal toxicity/withdrawal symptoms
Partial tetrasomy of 12p. Mosaicism for supernumary isochromosome 12p
US findings: diaphragmatic hernia, anal defects, holoprosencephaly
Other: cardiac defects, short limbs
Dx with skin biopsy and fibroblast chromosomes
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