HUMAN
KARYOTYPE
DNA CONDENSATION
CHROMOSOME MORPHOLOGY
METACENTRIC
SISTER CHROMATIDS
SUBMETACENTRIC
SHORT ARMS (p)
TELOMERE
CENTROMERE
LONG ARMS (q)
TELOMERE
AKROCENTRIC
SATELLITES
SAMPLES FOR
CHROMOSOMAL ANALYSIS
PRENATAL DG.:
• amniotic fluid
(amniocytes)
• fetal blood
• chorionic villi
∼
• umbilical cord and
other embryonal
or fetal tissues
POSTNATAL DG.:
• peripheral blood
(lymphocytes)
• bone marrow
• skin (fibroblasts)
• carcinoma samples
• other tissues
CYTOGENETIC ANALYSIS
Peripheral blood
Karyotype
Analyse metaphase
Venous blood
with heparine
Add phytohaemagglutinin
and culture medium
Digest with trypsin
and stain with Giemsa
Culture at 37°°C
for 72 hours
Spread cell suspension
onto slide by dropping
Add colchicine
Hypotonic
saline
Fixation
HUMAN KARYOTYPE
• 7 groups - depending on the lenght and morphology
• 22 pairs of homologous chromosomes - autosomes
• 1 pair of sex chromosomes
A
B
1-3
4-5
C
6 - 12
D
E
13 - 15
16 - 18
F
G
19 - 20
21 - 22
XX or XY
HUMAN KARYOTYPE
Chromosome groups characteristics
Group
Chromosomes
A
1–3
B
4 and 5
C
6 – 12 and X
D
13 – 15
Medium acrocentric
E
16 – 18
Short submetacentric
F
19 and 20
G
Size and Shape
Large metacentric
Large submetacentric
Medium submetacentric
Short metacentric
21 and 22 and Y Short acrocentric
G - BANDING PATTERNS
METAPHASE
KARYOTYPE
46,XY
FEMALE KARYOTYPE
46,XX