ch. 14 Developmental Genetics and Birth Defects

Flashcards about genetics in medicine, chapter 14, developmental genetics and birth defects

What is Dysmorphology?

The study of birth defects and abnormal development.

T/F: Gene expression occurs throughout a lifetime

true

Malformations Definition

Result from intrinsic abnormalities in genetic programs operating in development.

ex: extra or fused fingers

Deformations Definition

Dysmorphology

Caused by extrinsic (environmental factor) factors physically impinging on the fetus during development.

• common in 2nd trimester

• ex: arthrogryposes - contractions of the joints of the extremities, associated with twins or decreased amniotic fluid

Disruptions Definition

Destructions of irreplaceable fetal tissue, resulting from vascular insufficiency, trauma, or teratogens.

• difficult to treat

• ex: amnion disruption - partial amputation of a fetal limb with strands of amniotic tissue

Define Pleiotropy syndrome

What is Pleiotropic sequence?

Multiple abnormalities in parallel

• A single underlying causative agent may result in abnormalities in multiple organ systems

PS - mutation affects only 1 organ system at 1 point in time, and the disruption of that system causes the rest of the pleiotropic symptoms

*Ex: Robin Sequence

Environmental factors include mutagens and teratgon. Define both

1. Mutagen - cause damage by creating mutations

2. Teratogen - act directly and transiently on developing embryonic tissue

   1. ex: fetal retinoid syndrome*

Examples of environmental teratogens

Fetal retinoid syndrome, thalidomide syndrome, fetal alcohol syndrome

*List categories of teratogens:

Industrial agents, recreational substances, pharmacological agents, infectious agents

Factors influencing teratogenic effects include:

Dosage, acute vs. chronic exposure, time of exposure, stage of development, genotype of embryo

Thalidomide was developed in the 1950s to treat what?

Pregnancy-associated morning sickness

What are the components of TORCH?

Toxoplasma, Others, Rubella, Cytomegalovirus, Herpes simplex

Fetal Alcohol Syndrome Symptoms

Behavioral disturbances, brain defects, cardiac defects, spinal defects, craniofacial abnormalities

Tobacco related birth defects include…

low birth weight

Proliferation Definition

Cell division

Differentiation Definition

Cells acquire novel functions or structures

Migration Definition

Cell movement within the embryo

Apoptosis Definition

Programmed cell death

Three stages of embryonic development:

Pre-embryonic, embryonic, fetal

What are the three primary germ layers?

Ectoderm, mesoderm, endoderm

List the components of the ectoderm:

Epidermis of skin and its derivatives, epithelial lining of mouth and anus, cornea and lens of eye, nervous system, sensory receptors in epidermis, adrenal medulla, tooth enamel, epithelium of pineal and pituitary glands

List the components of the mesoderm:

Notochord, skeletal system, muscular layer of excretory system, circulatory and lymphatic systems, reproductive system, dermis of skin, lining of body cavity, adrenal cortex

List the components of the endoderm:

Epithelial lining of stomach and intestine, epithelial lining of digestive tract, epithelial lining of respiratory system, lining of urethra, urinary bladder, and reproductive system, liver, pancreas, thymus, thyroid and parathyroid glands

What is the single greatest causal factor of neural tube defects?

Vitamin deficiency

Folate supplementation can reduce incidence of NTDs by how much?

75%