EMBYRIOLOGY
اMuna Zuhair Dr.
It describe structural ,functional & metabolic disorders present at birth.The science which deals with these disorders is known as TETRALOGY . Major structural anomalies are seen in 2-3% at birth and another 2-3% are dignosed at the age of 5-6 years thus forming about 4-6% at the age of 6 years.Birth defects is a cause for about 21% of infants death…& in about 50% of birth defects the cause is unknown
CONGENITAL MALFORMATIONS
Minor anomalies are seen in about 15% of newborns ,and some of them are associated with major malformation,those having a single minor anomalies has the chance to get major anomalies in 3% of them ,those with 2 minor has the chance 10% & those with 3 minor anomalies has the chance in 20% to get major anomalies
Anomalies can be defind as a deviation from the normal which is compatable with a normal life and goes unrecognized until discovered after death,it is not inferior from the normal.
Biochemical defect is due to enzyme deficiency and it is diagnosed after birth as phenylketonuria
Amniocentesis:It is the withdrawal of some amniotic fluid & is used to obtain some cells from a skin or a cord of a growing fetus to be examined for chromosomal analysis to detect any defect due to chromosomal error as Mongolism(Trisomy 21) which can be diagnosed at the 7th weeks of development
1-Chromosomal factors: The defect may be in the sex or in the autosomal chromosomes.
A-Sex inherited diseases as in Turners & Klinefelter Syndromes.Turners syndrome which is characterizes by the followings:
1-Absence of the ovary ( Gonadal dysgenesis).
2-Webbed neck (it is short).
3-Low IQ . Normaly it is around 140 but in these cases it is
less than 60 leads to mental retardation.
4-A general appearance is of female.
5-The chromosomal constitution is XO.
CAUSES OF CONGENITAL MALFORMATIONS
B-Klinefelter syndrome : It is characterized by the followings:
1-Absence of the testes( Gonadal dysgenesis).2-Sterility due to absence testes.
3-Gynecomastia ( enlarged breast in a male due to hormonal imbalance.
4-The chromosomal constitution is XXY.
Autosomal inheritance diseases as in
Trisomy 21 ( Down syndrome) due to non- disjunction at chromosome 21 has:1-Hypotonia.
2-One palmer crease in the skin of the palm.
3-Excessive skin on the back of the neck.
4-Mental retardation due to low IQ.
5-More liable to Hypothyroidism .
6-Congenital heart defects.
7-Squint & refractive errors later in life.
Edward syndrome : Trisomy 17 or 18 due to non –disjunction ,its features are:
1-Low set ears.2-Micrognathia.
3-Mental Retardation.
4-Congenital heart disease.
5-Syndactyly of fingers.
DRUGS : as Quinin & Streptomycine both of them may lead to congenital deafness.
Tetracycline is associated with brownish discoloration of the teeth seen after birth.Sulpha drugs are associated with jaundice &kerniecterus with mental retardation
Thalidomide is strongly associated with congenital anomalies in the growing fetus & characterized by maily Gross deformities of long bones ( Amelia or meromelia),intestinal atresia and congenital heart defects.
The uses of Antithyroid drug on pregnant woman with hyperthyroidism leads to Congenital Hypothyroidism( CRETINISM) with congenital umbilical hernia and mental retardation.
ENVIROMENTAL FACTORS
Hormones as for example Pregestin derivatives given to pregnant woman to prevent abortion results in Hypertrophic clitoris & fusion of Scroto-labial folds…,Nutritional deprivation i.e malnourished pregnant woman leads to the birth of a baby with very low birth weight ,ill health baby due to poor immunity who might catch repeated infections or become marathmic and might die during infancy rather than anomalies.
