cytogenetic disorders Flashcards
The standard for cytogenetic nomenclature is the__
International System of Cytogenetic
Nomenclature (ISCN)
The nomenclature describing a chromosome complement can be broken down into three
basic parts:
: the total number of chromosomes, the sex chromosome complement, and
any chromosome abnormalities
A normal female would be ___
46,XX
These units are listed in order, separated by commas.
yes
A normal male would be__
A normal male would be 46,XY
- A trisomy 13 in female would be written as ___
47,XX,+13
- A monosomy 8 in a male would be written as __
45,XY,-8
it is not necessary to use a + or – sign when sex chromosome variation is
known to be constitutional or inherent, because the change in the chromosome
complement can be noted directly
sige
Autosomal monosomies are observed only
rarely among ___ and ___
spontaneous abortions and
live births
- ____ is found in 30% to 50% of all cases of
chromosomal abnormalities in fetal death
Autosomal trisomy
Only few autosomal trisomies result in live births (__
trisomy 8, 13, and
18)
Trisomy ___ (Down syndrome) is the only autosomal trisomy that
allows survival into adulthood
21
Patau
Syndrome (47,+13)
Trisomy 13
47 chromosomes, and the extra chromosome was identified as
chromosome 13
Trisomy 13: Patau
Syndrome (47,+13)
Only ____ in 15,000 live births involves trisomy 13, and the condition is
lethal
1
Half of all affected individuals die in the first month, and the mean
survival time is __
6 months
Abnormalities of trisomy 13 include ___
facial malformations, eye defects, extra
fingers or toes, and feet with large protruding heels
Infants with this condition are small at birth, grow very slowly, and are
mentally retarded
Trisomy 18: Edwards Syndrome (47,+18)
Occurs in 1 in 11,000 live births, average survival time is 2 to 4 months
Trisomy 18: Edwards Syndrome (47,+18)
For unknown reasons, 80% of all trisomy 18 births are
female
in trisomy 13 There is usually severe malformations of the brain and nervous
system, as well as congenital heart defects
true
__ is the only factor known to be related to trisomy 13
Parental age
is predisposing factor or t18
Advanced maternal age
- Heart malformations are almost always present, and heart failure or
pneumonia usually causes death
Trisomy 18: Edwards Syndrome (47,+18)
Clenched fists, with the second and fifth fingers overlapping the third and
fourth fingers, and malformed feet are characteristic
Trisomy 18: Edwards Syndrome (47,+18)
Trisomy 21: Down
Syndrome (47,+21)
described by
__ in 1866
Described by John Langdon Down in 1866
The only human autosomal trisomy in which a significant
number of individuals survive longer than a year past birth
Trisomy 21: Down
Syndrome (47,+21)
Found in 1 in every 800 births
Trisomy 21: Down
Syndrome (47,+21)
- Leading cause of childhood mental retardation and heart
defects in the US
Trisomy 21: Down
Syndrome (47,+21)
Characterized by prominent epicanthic fold in each eye, and
individuals usually have a wide, flat skull, and spots on the
iris
Trisomy 21: Down
Syndrome (47,+21)
They may have furrowed, large tongues that cause the
mouth to remain partially open
Trisomy 21: Down
Syndrome (47,+21)
Physical growth, behavior, and mental
development are retarded, and
approximately 40% of all ___
children have congenital heart defects
Down syndrome
They are susceptible to respiratory
infections and contract leukemia at a rate
far above that of the normal population
Trisomy 21: Down
Syndrome (47,+21)
It is observed that death in older adults
with Down syndrome is frequently due to
Alzheimer disease
__ is a leading risk factor for trisomy
Maternal age
Young mothers have a low probability of having trisomy 21 children, but the risk
increases rapidly after age 35 yea
omsim
The relationship between maternal age and nondisjunction focuses
on the duration of __ in females
meiosis
According to this idea, the embryo-uterine interaction normally
results in the spontaneous abortion of chromosomally abnormal
embryos, a process called
maternal selection
As women age, maternal selection may become less effective,
allowing more chromosomally abnormal embryos to implant and
develop
oki
Females with this condition are short and wide-chested with rudimentary ovaries
Turner
Syndrome
(45,X)
At birth, puffiness of the hands and feet is prominent, but that disappears in infancy
Turner
Syndrome
(45,X)
Many __ patients also have a narrow constriction of the aorta
turner
turner
There is no mental retardation associated with this syndrome
opo
Characterized by short stature (usually under 5 feet), skin flaps on the back of the neck,
and underdeveloped breasts
turner syndrome
Occurs with a frequency of 1 in 10,000 female births
turner syndrome
Two X chromosomes are needed for
normal development of the ovary,
normal growth patterns, and
development of the nervous system
in females
Turner Syndrome
(45,X)
Complete absence of an X
chromosome in the absence or
presence of a Y chromosome is
always lethal
Turner Syndrome
(45,X)
Occurs in approximately 1 in 1,000 male births
Klinefelter Syndrome
(47,XXY)
The features of this syndrome do not develop until
puberty
Klinefelter Syndrome
(47,XXY)
Affected individuals are male but have very low
fertility
Klinefelter Syndrome
(47,XXY)
- Individuals with this condition are generally tall and often
have long arms and legs
Klinefelter Syndrome
(47,XXY)
- They have genitalia and internal ducts that are male, but
their testes are reduced in size
Klinefelter Syndrome
(47,XXY)
Although 50% of affected individuals do produce sperm, a
low sperm count renders most individuals sterile
Klinefelter Syndrome
(47,XXY)
Gynecomastia is common, and hips are often rounded
Klinefelter Syndrome
(47,XXY)
Presence of an additional Y chromosome in an otherwise male karyotype
XYY Syndrome (47,XYY)
It results from the deletion of a small terminal portion of
chromosome 5
Cri du Chat Syndrome
(46,5p-)
biirubin pathway
heme - (heme oxigenase )- biliverdin - (biliverdin reductase)
–> b1 + albumin
they will reach liver. While in the liver, the carrier will now become
- Ligandin
–> B1 + ligandin
– acted upon by UDPT
conjugated by the conjugating enzyme
uridyl diphosphate glucoronyl transferase
–> B2
- gallblader – intestine (metabolized by the bacteria)
– ur0bilinogen
– either in intestine or in kidney
which bilirubin is water polar
b2
tighthly bounded b1 and albumin in liver is called
delta bilirubin
Has longer half-life than other forms of bilirubin
DELTA BILIRUBIN
Formed due to prolonged elevation of conjugated bilirubin
DELTA BILIRUBIN
Helps in monitoring the decline of serum bilirubin following
gall stones
A condition characterized by a
yellow discoloration or
pigmentation of the skin, sclera
and mucous membranes
jaundice
Normal – bilirubin total
0.2 - 1.0 mg/dL
in case the bilirubin goes up to 3.0 , it will be called as
overt jaundice - patient is not yet yellow
in case the bilirubin goes up to 5.0 , it will be called as
clinical jaundice - madilaw na ang patient
Prehepatic hyperbilirubinemia
INCREASE b1
INCREASE urobilinogen
NORMAL b2
Prehepatic hyperbilirubinemia
causes
all related to rbc
malaria
HDN
Implies damage to hepatocytes where both types of bilirubin are increased
Increase both B1 and B2
Hepatic hyperbilirubinemia
responsible for the uptake of the bilirubin in the hepatic cynosoites
Gilbert’s syndrome
Retention jaundice has an incease in __
B1
Crigler-Najjar
syndrome (Type I and II)
is absence of
UDGPT - conjugating enxyme
type 1 Crigler-Najjar
syndrome
lack of udpgt
type 2 Crigler-Najjar
syndrome
few UDGPT
syndrome for bilirubin that reached brain is called as
Crigler-Najjar syndrome
Hepatocyte injury
(hepatocellular) as
seen in:
o Viral hepatitis
o Cirrhosis and
alcoholic hepatitis
o Toxic liver injury
o
in Hepatocyte injury
(hepatocellular) as, mataas ang
b1 and b2
Impaired excretion of
products from the
hepatocytes as seen in:
o Dubin-Johnson
syndrome
o rotor syndrome
o Viral hepatitis
o Cirrhosis
Failure of bile to flow due to obstruction of the biliary tree
Increase B2
Post-hepatic hyperbilirubinemia
causes
o Choledocholelithiasis (stone in the common bile duct)
o Structures and spasm caused by bacteria
o pancreatic sarcoma/ cholangiocarcinoma
o Parasitism
number 1 enzyme for the detection of the biliary tree
gamma-glutamyl transferas
