Lecture 19 Birth Defects PDF

Unified Lecture 19 BIRTH DEFECTS RakanAlghtani) HIHD-211 - Batch 21 a TERM-3 Basic Science Department COSHP, KSAU-HS, KSA Teratology ▪ ▪ ▪ LO-1,2 Teratology is derived from the Greek noun teras, meaning monster. It is the study of birth defects, and a teratogen is something that either induces or am...

Unified Lecture 19 BIRTH DEFECTS RakanAlghtani) HIHD-211 - Batch 21 a TERM-3 Basic Science Department COSHP, KSAU-HS, KSA Teratology ▪ ▪ ▪ LO-1,2 Teratology is derived from the Greek noun teras, meaning monster. It 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 LO-1,2 2. Chemical agents & Drugs LO-1,2 MATERNAL CONDITIONS Hormones Anencephaly LO-1,2 Omphalocele Spina Bifida 4. 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 LO-1,2 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 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. LO-2 ▪ Alcohol: Fetal alcohol syndrome ▪ Cigarette smoking ▪ Cocaine Cleft Lip and Palate LO-1,2 Cleft Lip 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 and/genetic factors LO-3 environmental MALFORMATIONS Spina bifida Polydactyly Anencephaly LO-3 Omphalocele 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. LO-3 Gastroschisis (an abdominal wall disruption) LO-3 Foot disruption (amputation) due to Amniotic Band Sequence Partial disruption of the abdominal wall in the area supplied by the right omphalo-mesenteric artery LO-3 CONGENITAL ANOMALIES Types of abnormalities 3- DEFORMATIONS: An abnormal form, shape, or position of a part of the body that results from mechanical forces.   LO-3 Example: Clubfeet (equinovarus) are caused by compression in the amniotic cavity (oligohydramnions). Positional deformations of feet LO-3 Due to fetal constraint associated with Oligohydramnios “Malposition” during later weeks of pregnancy