cytogenetics 2 Flashcards
exam 2
loss of material
deletion
gain of material
duplication
exchange of material between two or more chromosomes
translocation
alteration within a chromosome
inversion
many defined before the genes invovled known
microdeletion
microdeletion syndrome
often result of submicroscopic deletion of more than one gene from chormosome
phenotype correlates with specific genes lost
bigger deletions, more features
microdeletion syndrome needs ____ to diagnose
FISH
microdeletion syndromes are more often _____, but can be _____
sporadic but can be dominant
Di George
microdeletion disorder
williams
microdeletion disorder
miler-dieker syndrome
microdeletion disorder
46,XX,del(15)(q11.2q13)
Prader-Willi/Angelman deletion
multiple genes are physically ______ on the chromosome
contiguous
VCFS
microdeletion disorder
exchange of material between 2 or more chromsomes
translocation
translocations may be
balanced or unbalanced
balanced translocations
identified by chance
unbalanced translocation
will have combination of monosomy and trisomy
Band assignment
numbering system based on landmarks and large the number further away from centromere
familial translocations
present at birth in some or all of cells in body and most are unique to a family
t(11;22)(q23;q11.2)
t(4;8)(p16;p23)
t(4;11)(p16.2;p15.4)
three constitutional familial recurrent
occurs between acrocentric chromosomes (13/14/15/21/22)
robertsonian translocation
robertsonian translocations
results in loss of non-critical genes in the short arm regions of the chromosomes involved
45,XX,der(13;14)(q10;q10)
robertsonian translocation
robertsonian translocation (2)
(1) count is decreased to 45
(2) q10 means that the creak is in the centromere and the long arm is present
balanced or unbalanced:
46, XY, t(1;8)(p22;q24)
balanced
balanced or unbalanced:
46, XX, der(8)t(1;8)(p22;q24)
unbalances
der(8) abnormal chromosome
balanced or unbalanced:
45,WW,der(13;14)(q10;q10)
balanced– Robertsonian
When there is an abnormal X
abnormal X inactivated if has XIST
when there is a translocation between X and autosome
normal x inactivated
when there is a unbalanced x translocation
abnormal x inactivated
pericentric
around centromere inversion
paracentric
outside centromere
not present at birth
acquired changes
cancer associated translocations like
t(9;22)
philadelphia chromosome
der(22)
t(9;22)
balanced translocation
presence of additional karyotype changes
clonal evolution
clona evolution is associated with
disease progression
complex cancer changes affects cells in the
bone marrow
why do translocations recur in cancer?
breakpoints= location of oncogenes- genes involved in driving cell cycle which result in production of abnormal protein that cannot be regulated/overproduction of a normal protein
why do deletions happen in cancer?
loss of one copy of gene and possible inactivation of the other copy removes cell cycle control point
constitutional trisomy
13,18,21
acquired trisomy
any
constitutional trisomy origin
meisosis
acquired trisomy origin
mitosis
constitutional monosomy
X
acquired monosomy
any
constitutional translocation balanced
no impact on phenotype; mostly unique to family
acquired translocation balanced
diagnostic, recurrent
constitutional translocation unbalanced
abnormal phenotype
acquired translocation unbalanced
normal phenotype
constitutional where
majority of cells
acquired where
site of cancer
