This document discusses congenital anomalies and their causes. It defines congenital anomalies as structural abnormalities present at birth, which can be caused by chromosomal abnormalities, genetic disorders, or environmental factors. Teratogens are agents that can disrupt normal development and cause birth defects. Common teratogens include chemicals, drugs, physical factors like radiation, and viruses. The critical periods of susceptibility to teratogens are outlined for different organ systems. Specific birth defects are described, such as those associated with Down syndrome, Edward's syndrome, and exposure to alcohol. Chromosomal abnormalities like translocations, deletions, and aneuploidies can also cause congenital anomalies.

1. Congenital anomalies
Presenters:
Dr. Shobily Algarni
Dr.Tamim khaled

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

11. klinefelter syndrome
47, XXY
Affect the male
incidence :1 : 1000
The primary features are sterility and
small testicles.

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

14. Drugs :
Alcohol: Fetal alcohol syndrome (FAS): intrauterine growth
restriction (IUGR), mental deficiency, microcephaly, ocular
anomalies, joint abnormalities, short palpebral fissures
Tetracycline : Stained teeth, hypoplasia of enamel
Phenytoin : Fetal hydantoin syndrome: IUGR, microcephaly,
mental deficiency, ridged frontal suture, inner epicanthal
folds, eyelid ptosis, broad depressed nasal bridge,
phalangeal hypoplasia
Cocaine : IUGR, prematurity, microcephaly, cerebral infarction,
urogenital defects, neurobehavioral disturbances

15. Viruses :
Rubella virus: IUGR, postnatal growth retardation, cardiac and great vessel
abnormalities, microcephaly, sensorineural deafness, cataract, microphthalmos,
glaucoma, pigmented retinopathy, mental deficiency, neonate bleeding,
hepatosplenomegaly, osteopathy, tooth defects
Herpes simplex virus : Skin vesicles and scarring, chorioretinitis, hepatomegaly,
thrombocytopenia, petechiae, hemolytic anemia, hydranencephaly
Cytomegalovirus: Microcephaly, chorioretinitis, sensorineural hearing loss,
delayed psychomotor/mental development, hepatosplenomegaly, hydrocephaly,
cerebral palsy, brain (periventricular) calcification

16. Bacteria :
Toxoplasma gondii : Microcephaly, mental deficiency, microphthalmia,
hydrocephaly, chorioretinitis, cerebral calcifications, hearing loss, neurologic
disturbance
Parasites: Malaria parasite infection during pregnancy and at delivery in mother,
placenta, and newborn