Chromosome Analysis Flashcards
Ballpark estimate
Bands on 11p increase with resolution
2 bands- 400
4 bands-550
5 bands- 850
Vancouver method
Determine the number of bands on 1,10,11,12 & X
Count only the dark bands
Bands on 10
Count light and dark bands on 10
13-14: 400
22-23: 500
32: 650
40: 850
Welborn Method
Count chromosome 1&2 and multiply by 6
Trisomy 18 (triple screen)
Low AFP, low uE3, low hcG
Trisomy 21 (triple screen)
Low AFP, low uE3, high hcG
Level 1 mosaicism
Called single cell mosaicism occurs when only one colony shows metaphases with an abnormal karyotype
Level 2 mosacisim
Called psuedomosacism occurs when an abnormal karyotype is limited to only one coverslip
Confined placental mosaicism
This occurs when an abnormal karyotype is found only in the extraembryonic membranes of the fetus
Level 3 mosaicism
True mosacism
Occurs when two or more colonies with the same abnormal karyotype are observed in two or more coverslip cultures
Chromosome groups
A: chromosomes 1-3
B: chromosomes 4&5
C: chromosomes 6-12, X
D: chromosomes 13-15
E: chromosomes 16-18
F: chromosomes 19-20
G: chromosomes 21-22, & Y
Nondisjunction
The failure of paired chromosomes (meiosis 1) or sister chromatids (meiosis 2 or mitosis) to separate at anaphase
If this occurs during meiosis 1 or during meiosis 2 the abnormal division can result in a constitutionally abnormal individual
Pericentric inversion
Centromere is involved in this inversion
Paracentric
Occurs when the breaks are on the same arm
Isochromosome
Occurs when there is a misdivision of the centromere
Is trisomic for one chromosome arm and one monosomic for the other arm
Turner syndrome abnormality and phenotype
45, X
Webbing of neck, short stature and amenorrhea
Klinefelter syndrome and phenotype
47,XXY
Tall stature, sterility, gynecomastia
Patau syndrome and phenotype
47,XX, +13
Cleft lip or palate, small head
Severe mental retardation and physical deformities
Edward syndrome
47,XX,+18
Severe mental retardation and physical deformities
Rocker bottom feet
Wolf Hirschhorn
Del(4)(p16)
WHS deletion
Craniofacial defects sometimes coined “Greek warrior helmet”
Pronounced growth and mental retardation
Cri-du-chat
Del(5)(p15)
CSF1R deletion
Distinctive cry that sounds like a cat, mental retardation, microencephaly
Retinoblastoma
Del(13)(q14)
Rb1 deletion
Tumors of the retina
Cat eye’s
Dup(22)(pter-q11)
Tetrasomy of 22p
Coloboma of iris
Prader-Willi
Del(15)(q11-2)
SNRPN gene
Maternal UPD
Mental retardation, obesity
Angelman
Del(15)(q11-2)
Paternal UPD
Puppet like gait, severe mental retardation, paroxysms of laughter, characteristic facies
Langer-Giedion
Del(8)(q24)
Facial and limb defects
Miller-Dieker
Del(17)(p13.3)
LIS1 deletion
Lissencephaly( smooth brain with incomplete development), severe mental retardation
DiGeorge
Del(22)(pter-q11)
Abnormal defects of the thymus and parathyroids, cardiovascular anomalies
Aniridia-Wilms’ Tumor
Del(11)(p13)
Absence of the iris of the eye
Mental and growth retardation
Tumors of the kidney
Chimerism
Have two or more cell lines
Can result from
The fusion of fraternal twin zygotes
Double fertilization of an egg and polar body
Exchange of hemopoietic stem cells by dizygotic twins
Clastogens
Cause chromosome breaks
Viruses
Radiation
Pesticides
MDS karyotype
-5
-7
+8
del(5q)
del(7q)
Acute promyelocytic leukemia (M3)
t(15;17)(q22-q11-12)
Acute myelomonocytic leukemia (M4)
Inv(16)(p13q22)
Acute monocytic leukemia (M5)
t(9;11)(p22;q23)
Other 11q23 rearrangements
Acute erythroleukemia (M6)
del(5q)
del(7q)
+8
ALL
Pre B
t(1;19)(q23;p13)
B-Cell
t(9;22)(q34;q11)
t(4;11)(q21;q23)
t(8;14)(q24;q32)
t(2;8)(p12;q24)
t(8;22)(q24;q11)
T-cell karyotype
Translocations involving
14q11
7p15
7q34
CLL karyotype
+12
14q32 translocations
CML
t(9;22)
i(17q)
+8
+Ph
+19
Polycythemia Vera
Del(20)
Burkitt’s Lymphoma
t(8:14)(q24;q32)
t(2;8)(p12;q24)
t(8;22)(p24;q11)
Follicular lymphoma
t(14;18)(q32;q21)
Anaplastic large cell lymphoma
t(2;5)(p23;q35)
Mantle cell lymphoma
t(11;14)(q13;q32)
Oma
Tumor (benign or malignant)
Sarcoma
Malignant epithelial tumor
Carcinoma
Malignant mesenchymal tumor
Size heteromorphisms
Most common are observed in chromosomes
1
9
16
Y
Smith-Magenis syndrome
Del(17)(p11.2)
SMS gene
Small ears, speech delay, hearing loss, eye misalignment, self-hugging, and scoliosis
Outgoing personalities and long term memory
Banding at 650 and higher
Williams syndrome (Williams-Beuren syndrome)
Del(7)(q11.23)
ELN gene
Heart and vascular conditions, small stature and growth delays, dental problems and intellectual disabilities
Outgoing and social
High blood calcium
Beckwith-Wiedemann syndrome
11p15 region
Increased body growth, large tongue, body growth can be asymmetrical
Pallister-Killian syndrome
Additional isochromosome of chromosome 12
Weak muscle tone, seizures, large forehead, cleft palate, intellectual disability
CML in blast crisis
+der (22)
+8
I(17q)
+19
AML with differentiation (M2)
t(8;21)(q22;q22)
Marginal zone lymphoma
t(11;18)(q21;q21)
Lower limit of resolution for karyotype, FISH, and microarray
Karyotype: 5-10Mb
FISH:
Duplication: approx 1Mb
Deletion: approx 200kb
Array: 1Kb
