Highlights 2.1 + 2.2 Flashcards
1) Define balanced
2) Define unbalanced
1) Genome has normal complement (amount) of chromosomal material
2) Has additional or missing material
When inversion mutations occur in somatic cells, rather than in the germ line, this is the hallmark of ______________
cancer
“Robertsonian translocation” is a medically significant example of what?
Dicentric chromosomes
Is Prader-Willi inherited from mom or dad?
Dad
After one baby with down syndrome, the chance of a second baby with it is ____% overall
1%
List the 3 mnemonics to remember trisomy
You can see a PG-13 movie at age 13
Patau’s, trisomy 13
You are Eligible to vote at age 18
Edward’s, trisomy 18
You can Drink at age 21
Down Syndrome, trisomy 21
If the gene is imprinted, it is marked based on donor sex and turned on or off?
Off
True or false: Regions that are imprinted from mom and dad are never on the exact part of the chromosome
True
Hyperphagia is the primary Sx of what genetic condition?
Prader-Willi syndrome
Explain why 46XX men are infertile
Because the Y chromosome carries additional genes for sperm development, which are not passed on with this recombination error (azoospermic factor AZFa, AZFb, AZFc)
List 3 ways a female can be XY
1) Deletion
2) Duplication
3) Loss of function mutation
1) Gonadal dysgenesis refers to what? What does this lead to?
2) What characterizes complete gonadal dysgenesis?
3) What characterizes partial gonadal dysgenesis? What is made difficult by this?
1) Progressive loss of germ cells; leads to underdeveloped and dysfunctional “Streak” gonads, & consequent failure to develop mature secondary sex characteristics
2) Normal-appearing external genitalia of the opposite chromosomal sex
3) Phenotypically ambiguous external genitalia, which does not quite match the chromosomal sex
-sex assignment is sometimes difficult due to ambiguous genitalia
What condition arises from defects in enzymes of the adrenal cortex required for cortisol biosynthesis?
CAH (congenital adrenal hyperplasia)
Name a disorder that targets the androgen target cells (receptors)
Androgen Insensitivity Syndrome
[caused by Incomplete Masculinization of 46, XY infants]
1) In normal alleles, expansion of (CGC)n in the 5’ untranslated region of the FMR1 gene occurs how many times?
2) What about in fragile X?
3) What does this lead to in fragile X?
1) 6-50 times
2) 200 repeats or more
3) This leads to methylation of the CGC repeat AND the adjacent FMR1 promotor, causing loss of FMRP expression
Fragile X:
Length of the repeat increases each time it is transmitted by females, so families develop worse disease along the line. This is called what?
“Anticipation”
List 5 features of the fragile X phenotype
1) Hyperactivity
2) Hand flapping or biting
3) Temper tantrums
4) Poor eye contact
5) Autistic features
List two conditions that often have “partial gonadal dysgenesis”
1) Congenital Adrenal Hyperplasia: virilization of 46XX infants
2) Androgen Insensitivity Syndrome: incomplete
masculinization of 46XY infants
