2. SLOs :
1. Describe the principles of congenital malformation
2. List the causes of congenital malformation
A. Define teratogens
B. Describe the different types of teratogens.
C. List the susceptible periods for each type of teratogens.
3. : Definition
Congenital Malformation: is a congenital
anomaly of the structure of some body part
of fetus
It’s caused by Chromosomal Aberrations are
the numerical or structural abnormalities of
the karyotype ,and from Genetic Disorders
by the mutation of the genes,
environmental and multi-factorial causes.
4. cont’s
Teratogenesis :
Teratogene is an agent that is able to affect normal ontogenetic development
and lead to a congenital anomaly.
5. Casuses of teratogenesis :
Chemical : such as lead, iron, copper
Antibiotics such as thalidomide, antineoplastic agents.
alcohol
Physical :
Ionizing radiation
Mechanical factors such as oligo ( small amount of amniotic fluid )
polyhydramnios (larg amount of amniotic fluid )
High temperature
X-rays
Environmental :
Toxoplasma
Rubivirus
6. Principles of Teratogenesis
When considering the possible teratogenicity of an agent,
such as a drug or chemical, three important principles
must be considered:
- Critical periods of development
- Dose of the drug or chemical
- Genotype (genetic constitution) of the embryo
7. Critical period :
The critical period for brain: development is from
3 to 16 weeks, but its development may be
disrupted after this because the brain is
differentiating and growing rapidly at birth.
Teratogens may produce mental deficiency during
the embryonic and fetal periods
8. Birth defect
Most common birth defect :
I. Down’s syndrome
II. Edward’s syndrome
III.Klinfelter syndrome
IV.Turner syndrome
9. Down’s syndrome
Down syndrome Also called Trisomy 21
There is an extra chromosome in 21
Iincidence 1:800
-Common clinical features :
Mental deficiency
brachycephaly
flat nasal bridge
10. Edward’s syndrome
Edward’s syndrome also known as trisomy 18
Incidence : 1:8000
Clinical features :
Mental deficiency
growth retardation
prominent occiput
12. Turner’s syndrome
Turner syndrome is a chromosomal condition that affects
development in females.
In the karyotype only one X there
Incidence: 1 in 8000 female births
13. Structural Chromosomal
Abnormalities
Translocation :
This abnormality is the transfer of a piece of one chromosome to a
nonhomologous chromosome. If two nonhomologous chromosomes
exchange pieces
Deletion :
When a chromosome breaks, part of it may be lost
EX: cri du chat syndrome