Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
34 Cards in this Set
- Front
- Back
|
What is the purpose of colcemid during karyotyping?
|
mitotic spindle inhibitor; suspend the cells in metaphase
|
|
|
To increase banding resolution, we should suspend the cells in what phase?
|
prophase, before DNA condenses
|
|
|
Where is the gene, Xp21.2?
|
short arm of X chromosome; region 2, band 1, sub-band 2
|
|
|
What is euploidy?
|
3n, 4n. any chromosomal abnormality with an entire new set of genes
|
|
|
What is aneuploidy?
|
extra chromosome (but not entire set)
|
|
|
What is worse? Monosomy or trisomy?
|
monsomy is worse; removal of a gene is worse than excess of the gene
|
|
|
Usual causes of aneuploidy?
|
nondisjunction; anaphase lag (chromosome doesn't connect to the spindle or doesn't move into new cell)
|
|
|
What is mosaicism?
|
in a patient with a chromosomal abnormalities, some cells may have normal chromosomal arrangements
|
|
|
What is a ring chromosome?
|
chromosome forms a ring and is usually degraded; serious consequences
|
|
|
What can we tell from this: 46, XY, del(16)(p11.2p13.1) ?
|
normal male except for a deletion on short arm of 16 (from region1, band1, sub-band2 to region 1, band 3, sub-band 1)
|
|
|
What is a pericentric inversion?
|
inverted genetic material involving the centromere
|
|
|
What is a paracentric inversion?
|
inverted genetic material NOT involving the centromere
|
|
|
How is an isochromosome formed?
|
one arm is lost, while one arm is duplicated
|
|
|
What is a Robertsonian translocation?
|
short arms of chromosomes (acrocentric) are lost and the long arms fuse into 1 chromosome
|
|
|
What is an acrocentric chromosome?
|
short arm is almost non-existant
|
|
|
When is maternal age not important in the formation of Down's Syndrome?
|
if it is caused by mosaicism or robertsonian translocation; maternal influence is only if it is caused by nondisjunction (most cases)
|
|
|
What is the gene dosage hypothesis and its relevance to Down's Syndrome phenotypes?
|
extra genes from the additional 21 chromosome = over-expression of certain genes
|
|
|
Coarctation of the aorta is common in which chromosomal anomaly?
|
Edwards (trisomy 18); Turner's
|
|
|
Why do patients with DiGeorge syndrome have bad immune systems?
|
DiGeorge = thymic hypoplasia = bad T cells
|
|
|
DiGeorge syndrome can be caused by what chromosomal anomaly?
|
chromosome 22q11.2
|
|
|
DiGeorge syndrome resembles what other syndrome?
|
velocardiofacial syndrome
|
|
|
Why are anomalies of the sex chromosomes more tolerated than with the autosomes?
|
X inactivation; and little genetic info on the Y chromosome
|
|
|
Where is the SRY gene located?
|
short arm of Y
|
|
|
What is Klinefelter Syndrome?
|
XXY in males; reduced male sex features
|
|
|
Klinefelter's results in hypogonadism in which gender?
|
males
|
|
|
Turner's Syndrome causes hypogonadism in which gender?
|
females
|
|
|
Turner's Syndrome has what chromosomal abnormalities?
|
Monosomy X
|
|
|
In patients with Klinefelters syndrome (hypogonadism), do they have longer or shorter CAG repeats?
|
long CAG repeats = hypogonadism in Klinefelter's
|
|
|
Most frequent cause of Turner's syndrome?
|
lost of short arm of an X; isochromosome
|
|
|
Most important cause of ammenorrhea (no menstruation)
|
Turner's syndrome
|
|
|
What gene is responsible for limb growth on the X chromosome, leading to short stature in Turner's patients (XO)?
|
SHOX haploinsufficiency
|
|
|
What is true hermaphroditism?
|
presence of both ovaries and testis
|
|
|
What is female pseudohermaphroditism?
|
genetically normal (XX), but exposed to high androgens (perhaps adrenal hyperplasia)
|
|
|
What is male pseudohermaphroditism?
|
genetically normal (XY), but maybe resistant to androgens or defective androgen synthesis
|
