Birth Defects - HIHD-211 Term 3 PDF

HIHD-211 TERM-3 BIRTH DEFECTS Dr Ahmed Aldarmahi Consultant and Associate Professor Basic Science Department COSHP, KSAU-HS, KSA LEARNING OUTCOMES By the end of this lecture the student should be able to: 1. 2. 3. Define teratology Describe the causes of birth defects Describe the types of abnormal...

HIHD-211 TERM-3 BIRTH DEFECTS Dr Ahmed Aldarmahi Consultant and Associate Professor Basic Science Department COSHP, KSAU-HS, KSA LEARNING OUTCOMES By the end of this lecture the student should be able to: 1. 2. 3. Define teratology Describe the causes of birth defects Describe the types of abnormalities Teratology ▪ ▪ Teratology is derived from the Greek noun teras, meaning monster. Teratology is the study of birth defects, and a teratogen is something that either induces or amplifies abnormal embryonic or fetal development and causes birth defects. ▪ Teratogens: Teratogens are substances that may produce physical or functional defects in the human embryo or fetus after the pregnant woman is exposed to the substance. ▪ They are generally classified into four categories, infectious agents, chemical, physical, maternal health and genetic. Infectious Agents  1- Infectious agents: a- Viruses; e.g., Rubella, cytomegalovirus, Herpes simplex, and varicella virus b- Protozoa :Toxoplasmosis c- Bacteria: Syphilis 2. Chemical agents & Drugs 3. PHYSICAL Radiation  Ionizing radiation is a potent teratogen.  Producing any type of birth defect depending on: 1. 2. 3. The dose Duration of exposure Stage of development of the conceptus at the time of exposure.  Radiation from nuclear explosions is also teratogenic, such as Hiroshima and Nagasaki 4. MATERNAL CONDITIONS Hormones Anencephaly Omphalocele Spina Bifida Genetic causes of Birth Defects  1- Numerical chromosomal abnormalities: - Trisomy 21(autosomes) → Down Syndrome - Monosomy X (sex chromosomes) → Turner Syndrome. - Trisomy of sex chromosomes → Klinefelter Syndrome.  2- Structural chromosomal abnormalities: - Translocation - Inversion Genetic causes of Birth Defects  3- Anomalies caused by mutant genes: - A mutation usually involves a loss or change in the function of a gene. - Mutation is permanent - Mutation can be increase by several environmental factors, e.g. large doses of radiation. 9 Major types of congenital abnormalities 1- MALFORMATIONS 2- DISRUPTIONS 3- DEFORMATIONS CONGENITAL ANOMALIES Types of abnormalities 1- MALFORMATIONS: A morphologic defect of an organ, part of an organ, or a larger region of the body (during formation) that results from an intrinsically abnormal developmental process.  Most of them have their origin during 3rd / 8th weeks of gestation.  Are caused by environmental and/genetic factors MALFORMATIONS Polydactyly Anencephaly Omphalocele Spina bifida CONGENITAL ANOMALIES Types of abnormalities 2- DISRUPTIONS: A morphologic defect of an organ, part of an organ, or a larger region of the body (after formation) that results from exposure to teratogens, or an interference with, an originally normal developmental process. Gastroschisis (an abdominal wall disruption) Foot disruption (amputation) due to Amniotic Band Sequence Partial disruption of the abdominal wall in the area supplied by the right omphalo-mesenteric artery ▪ Alcohol: Fetal alcohol syndrome ▪ Cigarette smoking ▪ Cocaine Cleft Lip and Palate Cleft Lip CONGENITAL ANOMALIES Types of abnormalities 3- DEFORMATIONS: An abnormal form, shape, or position of a part of the body that results from mechanical forces.   Example: Clubfeet (equinovarus) are caused by compression in the amniotic cavity (oligohydramnions). Positional deformations of feet Due to fetal constraint associated with Oligohydramnios “Malposition” during later weeks of pregnancy THANK YOU [email protected] 19