Development

Question 1

Causes of Congenital Anomalies

Answer 1

Chromosome imbalance 25% Copy number variants 10% Single-gene defects 20% Multifactorial 40% Teratogen 5%

Question 2

Isolated Anomaly Incidence per livebirths

Answer 2

Undescended testes 1:30
Heart defect 1:150
Club foot 1:300
Neural tube defects 1:500
Cleft lip + cleft palate 1:1000
Hypospadias 1:1000
Polydactyly 1:1500
Cleft palate 1:2000
Craniosynostosis 1:2000
Syndactyly 1:2000

Question 3

Deformation

Answer 3

Developmental Process is normal
Mechanical force alters structure

Physical restraints

Examples:
Oligohydramnios
Breech presentation
Bicornuate uterus

Clubbed feet could be caused by spina bifida

Question 4

Disruption

Answer 4

Developmental process is normal, but interrupted

Examples:
Amniotic band sequence
Fetal Cocaine exposure (Hole in the brain)

Question 5

Dysplasia

Answer 5

Abnormal tissue organization, microscopic structure

Examples:
Skeletal or connective tissue dysplasias
Ectodermal dysplasia (hyohidrotic dysplasia)

Question 6

Malformation

Answer 6

• Morphological defect from an intrinsically abnormal developmental process
• Examples: holoprosencephaly, congenital heart disease, neural tube defect

Question 7

Fetal Alcohol Syndrome

Answer 7

Growth retardation
Microcephaly
Mental retardation
Short palpebral fissures
Short nose
Smooth philtrum
Thin upper lip
Small distal palanges
Hypoplastic finger nails
Cardiac defects

Question 8

Four Basic processes during development

Answer 8

1. Proliferation- increase cell numbers by division
2. Differentiation- acquire novel functions or structure
3. Migration- move within the embyro
4. Programmed Cell Death- controlled elimination of cells

Question 9

Fate

Answer 9

process by which an undifferentiated cell moves through a series of discrete steps to manifest distinct functions of attributes to become a further differentiated cell (ab erythrocyte, a keratinocyte, or a cardiac myocyte)

Question 10

Specification

Answer 10

when a cell acquires characteristics but can still be influenced by environmental cues (signaling molecular, positional information) to change its ultimate fate

Question 11

Determination

Answer 11

The state of commitment when a cell either irreversibly acquires attributes or has irreversibly been committed to acquire those attibutes

• With the exception of the germ cell and stem cell comparements, all cells undergo specification and determination to their ultimate developmental fate

Question 12

Epigenetic Changes

Answer 12

• Regulation of gene expression depends on epigenetic changes, not permanent DNA changes (with exception of DNA arrangements in B and T cells of immune system)
• Examples of epigenetic changes: stable transcription complexes, modification of histones in chromatin, and methylation of DNA
• Epigentic control of gene expression is responsible for loss of developmental palsticity

Question 13

Establishment of Body Axes

Answer 13

A-P: anterior-posterior (cranial-caudal)
[Proximal-distal for limbs]
D-V: dorsal-ventral (back-front)
L-R: left-right axes

Patterning program of the embryo is overlaid onto these axes