Post on 02-Jan-2016
description
Birth defect, congenital malformation and congenital anomaly
Are synonymous terms used to describe structural, behavioral, functional and metabolic disorders present at birth
Causes of Birth Defects
Genetic/Chromosomal - 15-20%
Environmental (teratogens) - 10-15%
Combined - 20-25%
Multiple Gestations - 1%
Unknown - 40-50%
Genetic Causes
Molecules that regulate development
Enzymes
Structural genes
Localized to a Chromosome – gene unknown
Environmental factors (Teratogens)
Infectious agents-virusPhysical agents
X-rays, Hyperthemia, etcChemicals agents
alcohol, Cocaine, etcHormonesMaternal diabetes
Periods of VulnerabilityPreembryonic period Pregerm (0-2 wks) Usually Death
Embryonic period Organogenesis (3-8 wks) Abnormalities of Form
(malformations)
Fetal period Growth/Maturation (9 wks – birth) Growth Retardation Mental dysfunction
Fetus vulnerable Rapid cell proliferationCell migrationCell differentiation
Current Methods of Diagnosis
UltraSound/Amniocentesis
Karyotyping Spectral Karyotyping
FISH - translocation/target
PCR of target sequence
RT-PCR - gene expression
Spectral Karyotyping
All 23 chromosome pairs at one time
Different Fluorescent probes
Useful for translocations
Fluorescent In Situ Hybridization
Chromosome mapping
Identify and localize discrete chromosomal abnomalities
Deletions
PCRUsing 2 small primers (20 bp)25-40 cycles of: Denature Anneal Synthesize
Identify gene expression or mutation
PCR
Using 2 small primers (20 bp)
25-40 cycles of: Denature Anneal Synthesize
Identify gene expression or mutation
Growth in Length and Weight During the Fetal Period
Age(weeks) CRL(cm)
Crown-rump length
Weight(g)
9-12
13-16
17-20
21-24
25-28
29-32
33-36
37-38
5-8
9-14
15-19
20-23
24-27
28-30
31-34
35-36
10-45
60-200
250-450
500-820
900-1300
1400-2100
2200-2900
3000-3400