Genetic development: birth defects Flashcards
What are the two classes of transcription factors?
Unspecific and specific
What gene is responsible for the development of the anterior/posterior axis?
HOX genes
How do cells signal their relative position in an embryo?
cell-cell contact
secretion of morphogens
What are morphogens? How does it affect development?
Secretions of cells that signals their position, leading to a gradient in the embryo. Cells change their development based on [mophogens]
What is the sonic hedgehog protein? How does it influence development?
secreted from the notocord and develops a gradient. Helps organize the different cells in the brain and spinal cord
A mutation in shh leads to what?
Midline defects
What chemical must the Shh protein interact with for function?
Cholesterol
What is SLOS (Smith-Lemli-Opitz syndrome)?
Severe congenital malformations due to the impairment of Shh by a lack of cholesterol
What does cell changing shape in development consist of?
Rearranging the cytoskeleton and polarizing the secretions of proteins to apical or basal surface
What is polycystic disease (where cysts develop on the kidneys) the result of?
An overgrowth of a kidney duct due to a lack of polycstin 1 or 2. this disrupts cell’s ability to sense flow of fluid to stop and change development
Why is migration important in embryonic development?
CNS cells need to migrate from the neural tube in waves
What is lissencephaly?
Mutation or deletion of the LIS1 gene that interferes with the orderly migration of CNS cells away from the neural tube. Severe MR.
Apoptosis is a key feature in the development of which organs?
Heart separation of digits perforation of anal and choanal membranes connection b/t vagina and uterus immune system
How do autoimmune diseases develop?
failure of lymphocyte that react to the body to undergo apoptosis in development
What is hermaphroditism?
When pt has both testes and ovarian tissues
What is pseudohermaphroditism?
Pts have either testes or ovaries, but phenotype does not match their sex
What is the critical region on the Y chromosome for male development?
Sex-determining region of Y (SRY)
What happens if the SRY region is destroyed?
female develops with a Y chromosome
What happens if the SRY region is translocated to an X chromosome?
Male develops with XX chromosomes
What is female pseudohermaphroditism?
females with normal ovaries but ambiguous or male genitalia
Female pseudohermaphorditism is caused by Congenital adrenal hyperplasia (CAH). What is this?
Caused by a defect in a 21-hydroxylase involved in cortisol synthesis. Cortisol shunted to androgen synthesis
What are the three possible causes of male pseudohermaphroditism?
a defect in testes during development
problem in androgen biosynthesis
Deficiency in androgen receptor production
What is the tumor progenitor cell model?
Abnormalities in stem cells leads to a pool of cells that are incompletely differentiated. Benign, but can mutate, leading to CA.
