0930 - Foetal Development and Embryology

Question 1

List the types of genetic disease

Answer 1

Chromosomal Abnormalities
Single Gene Defects
Multifactorial Problems (Interaction of genetic with environment)
Teratogenic Problems (teratogens - e.g. thalidomide, alcohol, rubella)

Question 2

Define and give example of Malformation

Answer 2

Morphological defect of an organ, or larger region of body resulting from an intrinsically abnormal developmental process. i.e. there is a problem form start to finish. e.g. absence of thumb due to abnormality in apical ectodermal ridge that controls limb bud development.

Question 3

Define and give example of Dysplasia

Answer 3

Abnormal organisation of cells into tissues and the morphological results - e.g. Marfan syndrome. Essentially a problem of tissue growth at the cellular level.

Question 4

Define and give example of Disruption

Answer 4

Morphologic defect of an organ, part of an organ, or larger region of body resulting from extrinsic breakdown of, or an interference with, an originally normal process. E.g. amniotic band wrapping around a developing limb, leading to hypoplasia.

Question 5

Define and give example of Deformation

Answer 5

Abnormal form, shape or position of a part of body caused by mechanical forces (external disruption) - e.g. talipes equinovarus.

Question 6

Define and give example of Anomaly

Answer 6

Any deviation from expected or average type in structure, form or function which is interpreted as abnormal (as distinct from normal variant). Major have cosmetic or surgical consequences, minor have little impact on well-being (e.g. single palmar crease).

Question 7

Define and give example of Sequence

Answer 7

Pattern/cascade of multiple anomalies derived from a single known or presumed prior anomaly or mechanical factor (the flow-on effect). E.g. X-linked spina bifida.

Question 8

Define and give example of Syndrome

Answer 8

Multiple anomalies thought to be pathogenetically related and not representing a sequence - a lower level of anomalies than a sequence. E.g. Down Syndrome

Question 9

Define and give example of Association

Answer 9

Any non-random occurrence in one or more individuals of severe morphologic defects no identified as a sequence or syndrome. Typically involve major anomalies with similar embryologic timings. E.g. Vater (vertebral, anorectal, tracheo-oesophageal radial and renal) defects involve mesodermal derivatives that begin differentiation at 20-25 days.

Question 10

Define and give example of Developmental Field Defects

Answer 10

Result of non-distruptive disturbed development of a morphogenic field or pattern thereof. Links between cause and consequences not as well defined as sequences, but more reproducible than syndromes. E.g. asplenia occurs with dextropulmonary isomerism and pulmonary stenosis (bilateral right sidedness), whereas polysplenia occurs with levopulmonary isomerism and azygous venous return (bilateral left sidedness)