Chromosomal Aberrations Flashcards
false about adrenoleukodystrophy
A. X linked genetic disorder that occurs primarily in male
B. Disorder of peroxisomal fatty acid beta oxidation
C. Accumulation of very short chain fatty acids in tissues
throughout the body
C - very long dapat
enumerate 3 most severely affected sites @ adrenoleukodystrophy
myelin in the CNS
adrenal cortex
Leydig cells in the testis
location of main mutation @ adrenoleukodystrophy
Long arm of Chromosome X region 28
False about meiosis
A. daughter cells are diploid
B. at prophase I, tetrads are formed from homologous chromosomes
C. problems here would lead to genetic mutations
A - haploid dapat any daughter cell
main cause of aneuploidy
nondisjunction (or non-separation) during meiosis 1
results in N+1, N+1, N-1, N-1) or meiosis 2 (results in N+1, N-1, N, N
False about Monosomy
A. missing chromosome perturbs the overall gene balance in the chromosome set
B. missing chromosome allows any deleterious recessive allele on the single chromosome to be hemizygous and thus to be directly expressed phenotypically
C. Down Syndrome is an example of this
C - Down syndrome is trisomy. Example ng monosomy is Turner Syndrome (X0)
Which is mismatched?
A.Klinefelter syndrome : XXY
B.Patau syndrome: Trisomy 12
C.Edward’s Syndrome: Trisomy 18
B - Patau syndrome is trisomy 13
harelip and rocker bottom feet present at __
A.Klinefelter syndrome : XXY
B.Patau syndrome: Trisomy 13
C.Edward’s Syndrome: Trisomy 18
B
Faunlike ears present at __
A.Klinefelter syndrome : XXY
B.Patau syndrome: Trisomy 13
C.Edward’s Syndrome: Trisomy 18
C
identify the aneuploidy: Epicanthal folds, flat nasal bridges, upslanting palpebral fissures, midface hyperplasia, small mouths, cleft or high arched palates, delayed or absent teeth or enamel defects
48 XXXX
two ways for aberrations in chromosome structure to occur: enumerate
- Total amount of genetic information in the chromosome can change
- Genetic material may remain the same, but is rearranged
False about deletions
A. Deletions revert even if DNA is gone
B. Effect of deletion depends on what was deleted
C. Human disorders caused by large chromosomal
deletions are generally seen in heterozygotes since homozygotes usually die
A - irreversible sila
identify this chromosomal aberration & classify its type:
Affected individuals have underdeveloped vocal chords, wide set eyes, small head and jaw, moderate to severe mental health problems, very short
Cri-du-Chat syndrome
deletion
Tandem duplications are said to be adjacent to one another. Differentiate reverse tandem from terminal tandem.
Reverse tandem result in genes arranged opposite
order of original.
Terminal tandem are duplications at the end of a
chromosome
(1) What exactly happens in MECP2 Duplication Syndrome?
(2) What is MECP2 responsible for?
(1) Extra copy of MECP2 gene is caused by a
duplication of genetic material in the long (q) arm
of the X chromosome
(2) MECP2 – responsible for normal function of
nerve cells
False about MECP2 Duplication Syndrome (A) Almost exclusively in females (B) Characterized by moderate to severe intellectual disability (C) Weak muscle tone in infancy, feeding difficulties and poor or absent speech. (D)Some affected individuals experience loss of previously acquired skills (developmental regression)
(A) - almost exclusively in males dap at
identify the chromosomal aberration:Results when a chromosome segment excises and
reintegrates oriented 180o from original orientation
inversion
Differentiate pericentric from paracentric inversion
Pericentric Inversion – includes centromere
Paracentric Inversion – does not include
centromere
Which is false?
A.Inversion has same effect on homozygote & heterozygote.
B.Linked genes are often inverted together.
C.Gametes produced from pericentric and paracentric
inversions are imbalanced
A
Differentiate effect of inversion on homozygote & heterozygote
Homozygote will have normal meiosis Heterozygote effect depends on whether crossing over occurs (1) If no crossing over, no meiotic problem occurs (2) If crossing over happens, unequal conversion may produce serious genetic consequences
Which can happen in a heterozygous paracentric inversion but not in a heterozygous pericentric inversion?
A.One normal gamete
B.One gamete with duplication and deletion
C.One gamete with reciprocal duplication and
deletion
D.Two deletion products
D
A - happens in both
B & C - for heterozygous pericentric inversion only
Why do the great majority of inversions have no
phenotypic consequences in a way that alters its
gene expression?
In an inversion, the total amount of genetic information stays the same.
(a) alternate name of Angelman Syndrome
(b) in what chromosome is it involved
(a) Happy Puppet Syndrome
b) Involved in chromosome 15q11q13 (regions q11 and q13
False about Angelman Syndrome
A. Speech impairment, e and non-verbal communications skills higher than verbal ones
B. ataxia of gait and/or tremulous movement of limbs
C. combination of frequent crying, apparent sad demeanor
C - frequent laughing dapat, and apparent happy demeanour
When does translocation occur?
occurs when a segment of one chromosome becomes attached to another
What is reciprocal translocation?
Arise from two different mechanisms
a) Chromosomal breakage and DNA repair
(b) Abnormal crossovers (between non-homologous chromosomes
Reciprocal translocation leads to
A. change in total amount
B. rearrangement of genetic material
B. hence they are called balanced translocations
identify: Most common type of chromosomal rearrangement in humans. transfer of genetic material occurs in only one direction
Robertsonian (unbalanced) Translocations
true about Robertsonian translocations
(A)Breaks occur at the extreme end of the short arms of two non-homologous acrocentric chromosomes
(B)The small fragments fuse at their centrometric regions to form single chromosome
(C)The large acrocentric fragments are subsequently lost
A
B - large ang nagffuse
C - small ang nawawala
Robertsonian translocations occur only in these 4 chromosomes. enumerate!
13, 14, 15, 21
A translocation may happen for follicular lymphoma to occur. What chromosomes are affected in follicular lymphoma?
14 –> 18
in follicular lymphoma, what is transferred from chrome 14 to 18? what genes are affected?
IgH enhancer on chromosome 14 transferred to
chromosome 18 altering expression of bcl-2
genes causing follicular lymphoma
(a) chromosomes affected in translocation leading to chronic myelogenous leukaemia
(b) what exactly happens?
(a) 9 and 22
(b) Normal bcr1 gene on chromosome 22 fuse with
c-abl gene on chromosome 9 forming bcr1-abl
fusion protein
