L6: Dysmorphic Disorders

Question 1

Def of Dysmorphology

Answer 1

Question 2

Pathogenic Mechanisms of Dysmorphology

Answer 2

Malformation, Deformation, Disruption & Dysplasia

Question 3

Def of Malformation

Answer 3

• Early arrest or misdirection of normal development of an organ or a part of an organ.

Question 4

Causes of Malformation

Answer 4

It results from an intrinsic abnormal developmental process.

Question 5

Types of Malformation

Answer 5

Question 6

Examples of Malformation

Answer 6

Question 7

Def of Deformation

Answer 7

• Abnormal form, shape or position of part of body which has differentiated normally.

Question 8

Causes of Deformation

Answer 8

It results from mechanical forces (extrinsic defect).

Question 9

Examples of Deformation

Answer 9

Question 10

• Developmental defect isn’t essentially detectable at birth but develops later and still genetically determined.

Answer 10

…

Question 11

Def of Disruption

Answer 11

A morphologic defect of an organ or a part of an organ or a larger region of the body.

Question 12

Causes of Disruption

Answer 12

Question 13

Results of Disruption

Answer 13

• If it occurs early during gestation → atresia
• If it occurs later in gestation → necrosis

Question 14

Examples of Disruption

Answer 14

• Cerebral & cerebellar infarction
• Intestinal atresia (not duodenal)

Question 15

Def of Dysplasia

Answer 15

It is a structural defect.

Question 16

Causes of Dysplasia

Answer 16

Question 17

Results of Dysplasia

Answer 17

It affects just one general tissue type throughout the body

Question 18

Examples of Dysplasia

Answer 18

• Storage diseases (e.g., mucopolysaccharidoses).
• Ectodermal Dysplasia with involvement of skin, hair, nail & teeth.
• Osteogenesis imperfecta: All parts of the skeleton are affected

Question 19

Difference between:

• Disruption and deformation
• Disruption and malformation

Answer 19

Question 20

Types of Birth Defects

Answer 20

• Major versus Minor anomalies
• Isolated versus Multiple anomalies

Question 21

Major versus Minor anomalies

Answer 21

Question 22

Def of Major Anomalies

Answer 22

Question 23

Examples of Major Anomalies

Answer 23

• Cleft lip
• Pyloric stenosis
• VSD
• Down syndrome

Question 24

Percentage of Major Anomalies

Answer 24

3% of newborns

Question 25

Def of **Minor Anomalies**

Answer 25

Abnormalities that are of primarily cosmetic significance.

Question 26

Examples of **Minor Anomalies**

Answer 26

- Clinodactyly of the 5th finger - Preauricular tag - Epicanthal folds

Question 27

Percentage of **Minor Anomalies**

Answer 27

14% of newborns

Question 28

Isolated versus Multiple anomalies

Answer 28

Question 29

Def of **Isolated Anomalies**

Answer 29

Anomalies that affect only a single body site.

Question 30

Incidence of **Isolated Anomalies**

Answer 30

About 2/3 of major anomalies are isolated

Question 31

Examples of **Isolated Anomalies**

Answer 31

* Cleft lip + palate * Pyloric stenosis * Congenital heart disease

Question 32

Def of **Multiple Anomalies**

Answer 32

- Anomalies that affect multiple sites and have different causes & prognosis

Question 33

Examples of **Multiple Anomalies**

Answer 33

- The possible combinations of anomalies are limitless. - But, as a role, ≥ 2 major anomalies are usually associated with several minor anomalies.

Question 34

Etiologies of congenital anomalies

Question 35

Genetic Causes of congenital anomalies

Answer 35

- Chromosomal Abnormalities - Single Gene Defect - Multi-Factorial Inheritance

Question 36

Genetic Causes of congenital anomalies - Chromosomal Abnormalities

Answer 36

Question 37

Genetic Causes of congenital anomalies - Single Gene Defect

Answer 37

Question 38

Genetic Causes of congenital anomalies - Multi-Factorial Inheritance

Answer 38

Question 39

Environmental Causes of congenital anomalies

Answer 39

Question 40

Unknown Causes of congenital anomalies

Answer 40

* No near cause can be established. * Risk of recurrence is very low.

Question 41

Dx Approach for a child with congenital anomalies - Hx

Answer 41

Question 42

Dx Approach for a child with congenital anomalies - Ex

Answer 42

Question 43

Dx Approach for a child with congenital anomalies - INVx

Answer 43

Question 44

Investigations for a child with congenital anomalies - Chromosomal analysis

Answer 44

Question 45

Investigations for a child with congenital anomalies - Rad

Answer 45

Skeletal dysplasia, cardiac & renal anomalies.

Question 46

Investigations for a child with congenital anomalies - Autopsy

Answer 46

Should be encouraged if the child has died, in order to: - define the full extent of anomalies. - establish the cause of death.