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الاثنين 2/12/2013 أ.د.عبد الجبار الحبيطي
EMBYRIOLOGY الاثنين /12/2013 أ.د.عبد الجبار الحبيطي
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CONGENITAL MALFORMATIONS
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
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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
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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
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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 127th weeks of development
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CAUSES OF CONGENITAL MALFORMATIONS
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.
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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.
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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.
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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.
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ENVIROMENTAL FACTORS 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.
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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.
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