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;
51 Cards in this Set
- Front
- Back
|
What causes cat eye syndrome
|
4 copies of chromosome 22p+
|
|
|
How does an isodicentric chromosome form?
|
inverted duplication forms when resolution of 2 homologous acrocentric chromosomes results in a nugget with a centromere at each end
|
|
|
How would you test for Pallister-Killian prenatally?
|
Tetrasomy 12p won't show up on karyotype because the cells with this won't divide. Must order FISH or microarray.
|
|
|
Describe the 2 types of complex chromosomal rearrangements
|
Type 1--3 or 4 breaks, usually familial, usually maternal
Type 2--more than 4 breaks, usually de novo |
|
|
What are some indications for chromosome analysis of an individual?
|
1.Features of a recognizable syndrome
2. MR 3. unexplained major/minor anomalies 4. MCA 5. sexual anomalies 6. growth anomalies 7. some malignancies 8. failed neonatal adaptation 9. mosaic features (streaks, asymmetry) |
|
|
What is the sequence of the telemere cap?
|
TTAGGG
|
|
|
What is the name of the region after the telomere cap that is shared by all chromosomes?
|
telomere associated repeats
|
|
|
How long does each phase of the cell cycle last?
|
GI=12 h
S=6-8h G2=3-4h M= 1h |
|
|
In females, when does Meiosis I complete? When does Meiosis II complete?
|
MI-puberty
MII-fertilization (usually doesn't happen) |
|
|
Name 3 types of modifications that occur to alter histones
|
1. methylation of lysines/arginines
2.acetylations/ubiquitination of lysines 3. serine phosphorylation |
|
|
How are histones involved in turning genes off?
|
Methylated cPg islands recruit proteins like histone deacetylases, which remove acetyl grouos from histones to make chromatin compact=turns off expression
|
|
|
5 lines of evidence for imprinting
|
1. pronuclear transplantation in mice
2. human triploids have different phenotypes 3. chromosome microdeletion syndromes 4. genetic disease with unusual inheritance 5. UPD |
|
|
How does UPD 15 occur following maternal NDJ in Meiosis I?
|
Gametes can be either trisomic or monosomic. Trisomy rescue or monosomy rescue occurs.
|
|
|
Name 4 phenotypic risks of UPD
|
1. loss of gene exp due to imprinting
2. overexp. of an active gene 3. recessive disease 4. residual trisomy effects, since it once was |
|
|
Paternal UPD causes what % of Angelman?
|
3-5%
|
|
|
Chromosomal rearrangement in mom causes what % of Angelman?
Recurrence risk? |
less than 1%
10-20% |
|
|
Imprinting center mutations cause what % of Angelman?
Recurrence risk? |
3-5%
1% or 50% |
|
|
Name 2 genes included in the Beckwith-Weidemann region
|
IGF2
CDKN1C |
|
|
Paternal UPD11 can cause what?
|
Beckwith Weidemann
|
|
|
Name some mechanisms for imprinting
|
methylation os cytosine, chromatin compaction, DNA replication timing, others
|
|
|
Characteristic behavior in Smith-Magenis
|
sleep problems, hyperactivity, self-hugging, self-injury (put things in orifices, pulling out nails)
|
|
|
In 22q, what happens if calcium too low?
|
seizures
|
|
|
Features of 22q
|
Heart defect
palate defects immuno defects ENT defects hypocalcemia eye abnormalities renal defects neurologic abnormalities DD |
|
|
What % of 22q patients are female?
|
52%
|
|
|
% of 22q with autoimmune disease
|
about 4%
|
|
|
Most 22q patietns with hearing loss have what type?
|
conductive
|
|
|
% of 22q kids with DD
|
90%
|
|
|
% of 22q kids with language delay
|
100%
|
|
|
Name the 4 recombination products of a pericentric inversion
|
1. Duplication/deficiency
2. Inverted chromosome 3. Duplication/deficiency 4. Normal chromosome |
|
|
Q banding recognizes what regions on what chromosomes?
|
AT regions, 1, 9, 16, acrocentrics, distal part of Y
|
|
|
G banding recognizes what sequences?
|
AT regions, chromosomes 1, 9, 16, acrocentrics, distal Y
|
|
|
C banding recognizes what regions and what chromosomes?
|
constitutive heterochromatin--1, 9, 16, distal Y
|
|
|
R banding is good ofr what regions?
|
telomeres
|
|
|
In proper nomenclature, for a given chromosome, which abnormality is listed first--numerical of structural?
|
numerical is always listed first
46, XX, der (13;21), +21 46, XX, +13, der (13;21) |
|
|
Optimal gestation range for CVS
|
10-12 weeks
|
|
|
What is used to stimulate mitotic activity in a cell prep?
|
PHA
|
|
|
What characteristic do bone marrow cells and the trophoblast layer of chorionic villi cells have in common?
|
they divide spontaneously
|
|
|
Name 3 classes of commercially available DNA probes
|
repetitive sequence probes
locus-specific probe whole chromosome paints |
|
|
In a reciprocal translocation, which is a higher risk of an abnormal liveborn--small distal segments or large distal segments?
|
Small is more of a risk, because they are more likely to survive
|
|
|
Most unbalanced karyotypes seen in liveborns from reciprocal translocations are from which 2 types of segregation?
|
adjacent-1 or 3:1
|
|
|
Difference btwn primary and secondary nondisjunction
|
Primary occurs during meiosis. Secondary happens during mitosis and results in a mosaic embryo.
|
|
|
As maternal age increases, more recombination occurs where?
|
near telomeres
|
|
|
Most Down syndrome occurs from what event?
|
Nondisjunction in maternal Meiosis I
|
|
|
If paternal gametes undergo nondisjunction, it usually happens when?
|
Meiosis II
|
|
|
Major clinical features of Down syndrome
|
hypotonia
skeletal anomalies (neck instability) GI anomalies myopia, strabismus, nystagmus hearing loss hypothyroidism hypogonadism |
|
|
Percent of kids with Down syndrome who have heart defect
|
40-50%
|
|
|
Alzheimer risk in Down syndrome compared with general population
|
25% compared with 6%
|
|
|
Percent of patients with Down syndrome who have hearing loss
|
65%
|
|
|
Major physical features of trisomy 18
|
microcephaly with prominent occiput
thin, weak, cry doll-like face clenched fist with overlapping fingers arches on dermatoglyphics rocker bottom feet 2-3 toe syndactlyly club feet central apnea |
|
|
Most common heart defect in tri 18
|
VSD
|
|
|
Internal malformations in tri 18
|
GI malformations (Meckel's diverticulum or malrotation)
omphalocoele CNS abnormalities Genital abnormalities Heart defect |
