Lecture 54 Teratology and Human Birth Defects

Question 1

What is teratology?

Answer 1

branch of embryology and pathology concerned with the production, developmental anatomy, and the classification of malformed embryos and fetuses

Question 2

What percent of newborns have major structural anomalies?

Answer 2

3%

Question 3

Major developmental defects are more common in ____ embryos.

Answer 3

early

Question 4

What is a malformation?

Answer 4

an intrinsically abnormal developmental process

Question 5

_____ is an interference with an originally normal developmental process.

Answer 5

disruption

Question 6

_____ is an abnormal form resulting from mechanical forces.

Answer 6

deformation

Question 7

What is dysplasia?

Answer 7

abnormal organization of cells into tissues

Question 8

What is the term for a disturbance of a single developmental field?

Answer 8

polytopic field defect

Question 9

_____ is a pattern of anomalies created by a single structural defect or mechanical factor, where as a ______ is a pattern of anomalies that are pathogenetically related.

Answer 9

sequence

syndrome

Question 10

What is an association?

Answer 10

non-random occurrence of multiple anomalies in 2+ people

Question 11

In Pierre Robin, micrognathia leads to a chain of events. What type of pattern of anomalies is this condition?

Answer 11

sequence

Question 12

In Down’s (Trisomy 21), independent malformations are present in several organ systems. What type of pattern of anomalies is this?

Answer 12

syndrome

Question 13

What type of genetic defect causes achondroplasia?

Answer 13

“mutant genes” or mutations

Question 14

Name five environmental agents that can result in various anomalies.

Answer 14

drugs/chemicals, radiation, infections, maternal factors, mechanical factors

Question 15

What are the four clinically significant types of birth defects?

Answer 15

malformation, disruption, deformation, dysplasia

Question 16

1/3 of all birth defects are caused by what?

Answer 16

genetic factors

Question 17

Chromosomal abnormalities are common in early zygotes/embryos. These can be _____ or _____.

Answer 17

numeric

structural

Question 18

What are the three types of numerical chromosomal abnormalities?

Answer 18

Polyploidy
Aneuploidy
Nondisjunction

Question 19

What are the two types of structural chromosomal abnormalities?

Answer 19

chromosomal breakage and abnormal combination

drugs, chemicals, and viruses

Question 20

What term is described by a deviation from the human diploid number of 46 chromosomes?

Answer 20

aneuploidy

Question 21

What is nondisjunction?

Answer 21

the failure of a chromosome pair or 2 chromatids to disjoin during mitosis or meiosis

Question 22

What is the most common numeric chromosomal abnormality?

Answer 22

nondisjunction

Question 23

Edwards Syndrome is Trisomy ____ and Patau Syndrome is Trisomy ____.

Answer 23

18

13

Question 24

What syndrome is caused by the most common abnormality in spontaneous abortions (1/8000 live births)?

Answer 24

Turner Syndrome (X)

Question 25

During the first ____ weeks, teratogenic agents usually kill the embryo or have no effect.

Answer 25

2

Question 26

During the embryonic period (week 3-8), teratogenic agents can do what?

Answer 26

disrupt development and may cause major birth defects or malformations

Question 27

During the fetal period (week 9-birth), teratogenic agents may produce morphologic and functional abnormalities, particularly of what structures?

Answer 27

brain and eyes

Question 28

What is a teratogen?

Answer 28

any agent causing a congenital anomaly

Question 29

What is the dose-response relationship?

Answer 29

the greater the exposure the more severe the phenotypic effect; severity of abnormalities is directly proportional to the concentration of the teratogen; different species or individuals may respond differently to the same substance