Exam 1 studying Flashcards
True or false: Prader-willi is passed down by the father, Angelman is from the mother
True
Klinefelter syndrome karyotype
47,XXY
Turner syndrome karyotype
45X
Which can occur at spontaneous breaks in the DNA, regional mutations or single gene mutations?
Regional
True or false: In most cases, once a mutation occurs it is stable when transmitted from one generation to the next
True
What may lead to either “missense mutation” or “nonsense mutation”?
Single nucleotide substitution or “point mutation”
Do missense or nonsense mutations disrupt the code enough that the protein is unusable?
Nonsense
What condition is a de novo gain of function missense mutation? (hint: it’s autosomal dominant)
Achondroplasia
When all of a mom’s babies have the disease, it’s probably ________________
mitochondrial
When multiple alleles would be worse than having just one, what can be said abt the condition?
It’s incompletely dominant
True or false: Penetrance is all or nothing for the individual
True
What is the inheritance pattern of hereditary hemochromatosis?
Autosomal recessive
1) What does hepcidin do?
2) What does HFE do to it?
1) Block further absorption when supplies are good
2) Inhibits hepcidin signaling; disinhibiting enterocytes and macrophages to release iron
_____________________ as an example is incompletely dominant, because it is usually fatal when homozygous
Achondroplasia
Male-limited precocious puberty: is it autosomal recessive or dominant?
Dominant
Compare the inheritance of x-linked recessive and dominant
1) Recessive: from mom or dad
2) Dominant: a male gets it from his mother
When both copies of a chromosome derive from the same parent this is called what? How does this happen?
Uniparental disomy; trisomy “rescue”
Differentiate b/t 2 types of uniparental disomy
1) May come from sister chromatids – idiosomy
2) May come from homologues – heterodisomy
If the gene is imprinted it is marked based on donor sex and turned _______-
off
True or false: Regions that are imprinted from mom and dad are never on the exact part of the chromosome
True
Describe the mutation that causes Prader-Willi
Chromosome 15 has maternally imprinted near q12 normally
In Prader-Willi there is a paternal deletion of 15q11.2-11.13; baby now has no DNA there
What is the rare type of prader-willi? Describe
Parental Disomy type:
In rare cases, mom can pass along both copies of Chromosome 15 in lieu of any paternal copy
Describe the mutation that causes Angelman syndrome
In this disease, mother’s chromosome 15 is passed along with a deleted region
Father’s normal, imprinted chromosome lacks any expressed genes in this region (as it should)
DiGeorge syndrome, velocardiofacial syndrome, conotruncal anomaly face syndrome can all result from what one cause?
Deletions/ duplications on chromosome 22
What condition can occur either through terminal or interstitial deletion on long arm of Chromosome 5?
Cri du chat syndrome
(Degree of intellectual impairment correlates with size of deletion)
