Prenatal Final Review Fall 2010

a

acro

brachy

clino

syn

Anencephaly

Hypertelorism

Syndactyly

Meningoencephalocele

Coloboma

Aniridia

Lissensephaly

Holoprosencephaly

Arachnodactyly

Polydactyly

Fetal hydrops

Cystic hygroma

Potter’s sequence

Oligohydraminos

Polyhydraminos

Gestational trophoblastic disease

Choriocarcinomas

Partial hydatidiform mole

Partial hydatidiform mole

Complete hydatidiform mole

Definition of teratogen

abnormal phenotype

• Malformation

• Disruption

• Deformation

• Dysplasia

Teratogen exert their influence when differentiation and morphogenesis are at their peak (such as the first 8 weeks of pregnancy)

The dose affecting the fetus is deterined by mother's ability to metabolize the toxic substance (such a maternal diabetes

The use of a specific teratogen can lead to specific phenotypes of children

Sometimes the mother's disease can affect the offspring (such as PKU

Such as CMV, Rubella, and Toxoplasmosis, Herpies simplex (TORCH)

Such as Diabetes Mellitus, PKU, Lupus, Thyroid disease

Alcohol, tobacco, cocaine

Such as Retinoic acid, thalidomide, valproic acid, warfarin

Can cause mental retardation, microcephaly, growth impairment, usually affects germ cells

--Advanced maternal age (35 years or older)

-- Have a positive maternal serum screen

--have fetal abrnomaltiy detected upon ultrasound

--are carriers of a chromosome abberation (or father does)

-- Had previous child with a chromosome abnormality

-- Other factors

Abnormal MSAFP--> Positive maternal serum--> diagnostic Ultrasound =>
Amnio not indicated
OR Amniocentesis

-- Maternal marker serum screening is performed at 15-16 weeks gestation
Then Ultrasound
Amniocentesis

detects aneuploidy of 13, 18, 21, X or Y (can detect ultrasound abrnomalties 85% of the time)

****Detects 71.9% of chromosomeal abrnomalties in Amniocenesis population
****78.% in Avd. Mat. Age
****80% in triple screen
****85% in ultrasound

-- has all
--To become complete media, it must have Fetal Calf Serum, or Fetal bovine serum

-- used to make complete media and the most common used growth supplement

--Essential component of media, Cells cannot produce by themselves… Must be made every 10 fresh. Is not stable

-- stop the growth of fungus, yeast, and bacteria(is optional component)

---mitotic cells-- dividing cells are round and shiny (doublets are important, it means that there are alive..
---cell density-- flask 70% confluencey / amnio you look at colonies (100 cells )

Antiemetic
blocks dopamine receptors in CRTZ
blood borne agents

---Do not touch the bottom 3/4 of a pipet to anything

---Clean work surface before starting work, after spills and after completing each task.

---Avoid talking while working in the biological safety cabinet

---Use of sterile containers

• Should be straw colored in appearance

• Urine will have pH <7.0 and have cube shaped crystals on the Fern Test

• Amniotic fluid will have pH of >7.0 and have fern shaped crystals on Fern test

 Alkali denaturation test:
• Alkali converts HbA to alkaline hematin, which is insoluble and precipitates. Fetal Hemoglobin (HbF) is more resistant to denaturation in alkaline solution than adult hemoglobin (HbA). (If you don’t get a ppt, then its fetal blood)

Maternal blood is removed from amnio in the first 2-3 mL

remove any maternal decidua and blood clots (dark villi)

, only membranes of fetal origin should be identified as fetal material and culture

 Shorter turn-around time

 Relative small cell loss during harvesting allows multiple cultures to be established even when the sample is small.

 The success rate in samples with few cells is increased

 Easier distinction between true mosaicism and pseudomosaicism

 Must have 70% confluency

 Number and size of colonies (should have at least 5 colonies)

 Presence of dividing cells

 Must feed 24 hours prior to harvest

used to help prevent fungal infections

used to help prevent yeast contamination, also helps prevent bacterial contamination

used to help prevent bacterial contamination, and is stronger and therefore more toxic than penicillin/streptomycin

used to prevent bacterial contamination

--If one colony has a mixture of abnormal and normal cells, and no other colony shows that abnormality, the abnormal cells are usually considered an in vitro artifact.

--If the first cell examined from a colony shows an abnormality, the technologist must immediately examine other mitotic cells from the same colony.

--The examination of additional cells from the same colony may cease if a normal cell is observed and report a mixed colony.

--When a colony has only one metaphase spread, and score and additional 10-20 colonies only if the abnormality is consistent with a viable numerical or structural mosaicism. If inconsistent, it is considered pseudomosacism.

---If detected in a direct CVS preparation, especially if a lethal trisomy, usually not a true mosaicism.

---If abnormality detected in a CVS culture, need amniocentesis confirmation. CVS is placenta tissue derved from fetal but not fetal tissue

---If abnormality detected in amniotic culture
--Usually not followed up if a single culture vessel
--Followed up and ultrasound examination appropriate when:
-physician and family desire confirmation
-only a single culture is available
-poor cytogenetic qulaity
-46,XX/46,XY admixture in multiple cultures

---If normal results on confirmatory studies cannot rule out mosaicism nor ensure a normal outcome of the pregnancy, and if mosaicism is confirmed, the clinical interpretation is uncertain in terms of risk to the fetus, follow up studies will be needed.

(1 from each 15 different colonies)

( analyze 5 colony) or a minimum of 5 cells must be completely analyzed

At least two metaphases, or one metaphase per cell line, demonstrating a minimum of 400 bands per haploid set should be karyotyped

Low risk of mental retardation or birth defect if:
1. balanced rearrangement
2. familial rearrangement
3. familial extra marker


High risk of metal retardation or birth defect if:
1. unbalanced rearrangement
2. De novo rearrangement
3. De novo extra marker

Should study parents for the relatively common t(11;22) associated with Cat’s Eye Syndrome. Children with this syndrome have an extra marker chromosome determined through family studies to be an extra deleted chromosome 22.

If marker appears to be a new mutation, C-banding, Ag-NOR staining and FISH should be performed.
C-banding will determine dicentricity;
Ag -NOR can be used to determine if satellites are present;
FISH can be used to identify chromosomal origin.

Should be followed-up by a detailed ultrasound examination

b. Tetraploidy is a common artifact in monolayer cultures

Rare cases have been reported for chromosomes 21 and 22.

Should be considered only if multiple cultures have colonies with the same monosomy.

Occurs in 1/2500 amniotic fluid cells cultures.

The majority of newborns with this prenatal diagnosis have had a normal phenotype; therefore no syndrome has ever been described.

47,XXX and 47,XXY frequency increase with advancing maternal age and represent 10% of all prenatally detected chromosome abnormalities.

45,X/46,XY Mosaicism
--Known association with Ullrich-Turner syndrome, mixed gonadal dysgenesis, and ambiguous genitalia
--Ultrasound examination imperative because only 5% risk of abnormal sexual differentiation in prenatally diagnosed 45,X/46,XY cases.

45,X/46,XX Mosaicism
--Consistent with a normal phenotype in most instances
-- Suggestion of an increased risk of miscarriage or early menopause in these individuals

--Should be confirmed by amniocentesis