V.N.

KARAZIN KHARKIV NATIONAL UNIVERSITY

MEDICAL SCHOOL
DEPARTMENT OF NORMAL ANATOMY AND PHYSIOLOGY

METHODOLOGICAL DEVELOPMENT

practical classes for students

Educational discipline "Medical Biology"

KHARKIV
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Topic № 19 "Cytogenetic methods. Chromosomal diseases "

1. The relevance of the topic is determined by the fact that the cytogenetic method
allows to study the human karyotype, and thus is central to the diagnosis of
chromosomal diseases, including prenatal diagnosis to prevent the birth of sick
children. The method also allows to assess the mutagenic effects of environmental
factors, as it allows to detect somatic mutations associated with changes in the
number and structure of chromosomes.
The material contributes to the formation of future doctors' clinical thinking, and is
also important in the future practice of general practitioners, obstetricians and
gynecologists, in medical and genetic counseling.

2. Objectives of the lesson:

2.1. Learning objectives:
- to acquaint the student with the manifestations of major human
chromosomal diseases, to give an idea of prenatal diagnosis of chromosomal
diseases.
- the student must know the classification of hereditary human diseases, the
essence of the method of karyotyping and the main indications for its use, the
stages of making a metaphase plate; the essence of the FISH method; what is sex
chromatin, indications for the definition of X- and Y-sex chromatin as a method of
diagnosing hereditary human diseases, karyotypes in chromosomal diseases caused
by disorders of the number or structure of chromosomes;
- to give students the opportunity to master the ability to analyze karyograms
and determine the type of chromosomal changes, skills of recording human
carotype in normal and pathological.
- give students the ability to study sex chromatin in human buccal
epithelium.

2.2. Educational goals: to be able to explain to the patient the mechanisms of

human chromosomal diseases, the essence of cytogenetic methods and indications
for cytogenetic diagnosis.
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3. Interdisciplinary integration.

Disciplines Know Be able

1. Previous
School course Characteristics of the normal Recognize a normal human
Biology, 10 classes, human karyotype photokaryogram
topic "Features of the
karyotype of different
organisms"

2. The following Chromosomal diseases. Characterize the etiological

disciplines Mechanisms of genomic and factors of occurrence and
Pathological physiology chromosomal mutations. development of hereditary
Topic: The role of Syndromes caused by changes diseases and disorders of fetal
heredity, constitution, age- in the number of development
related changes in chromosomes. The main
pathology. phenotypic manifestations of
chromosomal aberrations.

Medical genetics Modern methods of To interpret karyograms in

Subject. General chromosome research: norm and at pathology.
characteristics of The importance of the
chromosomal diseases. Down cytogenetic method in clinical
syndrome. Cytogenetic practice: diagnosis of
methods. chromosomal diseases,
diagnosis of a number of
mendelian diseases associated
with chromosome instability,
diagnosis of cancer and some
forms of leukemia, assessment
of mutagenic effects of drugs,
monitoring of environmental
damage.

3. Intra-subject integration The structure of the metaphase Determine the shape of

Lesson topic № 4 chromosome, the shape of chromosomes, classify human
Chromosome morphology. chromosomes, the chromosomes according to the
Human karyotype characteristics of the human Denver classification of
karyotype according to the chromosomes
Lesson topic № 14: Denver classification of
Variability, its forms and chromosomes Explain the importance of
manifestations Classification and mechanism mutations and mutagenic
of gene mutations factors (mutagens) of different
nature in the occurrence of
human chromosomal diseases
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4. Lesson content
Inherited diseases – diseases caused by mutations
Classification of inherited diseases
• Chromosomal diseases - caused by changes in the number or structure
of chromosomes
• Monogenic diseases - caused by changes in the nucleotide sequence
of DNA
• Multifactorial diseases - due to hereditary predisposition and the action
of adverse environmental factors
Cytogenetic methods are based on the study of the human karyotype, ie
allow to determine the number and structure of human chromosomes.
The main cytogenetic methods include:
1) karyotyping;
2) molecular cytogenetic methods;
3) determination of sex chromatin.

The main indications for cytogenetic diagnosis

1. Suspicion of chromosomal disease by clinical symptoms (to confirm
the diagnosis).
2. Children with multiple congenital malformations, psychomotor
developmental delays, delays and anomalies of sexual development and
their parents.
3. Married couples with infertility, miscarriage (more than two
miscarriages), stillbirth, the presence of a child with congenital
malformations or chromosomal disease.
4. Leukemia (for differential diagnosis, evaluation of treatment
effectiveness and prognosis).
5. Assessment of mutagenic effects (radiation or chemical).
Karyotyping method
Allows you to study the karyotype as a whole (ie the number and
structure of chromosomes). Human chromosomes are studied at the
stages of metaphase and metaphase of mitosis.
1) 1) Study of metaphase chromosomes. At this stage, the
chromosomes are maximally helical and well visible under a light
microscope.
The preparation of metaphase chromosomes of one is called the
metaphase plate.

To diagnose most chromosomal diseases, metaphase plates are made

from peripheral blood lymphocytes. Also suitable are fibroblasts of the skin,
red bone marrow cells. For prenatal diagnosis, amniotic fluid cells,
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chorionic villi, placenta, and embryonic tissues are cultured. Cells from
various tissues of aborted embryos are also used.
Metaphase plates from peripheral blood lymphocytes are obtained as
follows.
1. Venous blood (1-2 ml) is used for karyotyping. Blood is placed in a
special nutrient medium (Environment 199, "Needle", etc.) with
phytohemagglutinin (PHA). PHA (legume protein) causes immunological
transformation of leukocytes and their division by mitosis. The culture is
placed in a thermostat for 48-72 hours.
2. Colchicine (or colcemid) is added 2-3 hours before the end of
cultivation. Colchicine is obtained from the late autumn plant (Colchicum
autumnale). It destroys the division spindle and stops cell division at the
metaphase stage.
3. The next stage of drug preparation is treatment of cells with hypotonic
solution of potassium chloride or sodium citrate. In a hypotonic solution,
cells swell, interchromosomal bonds break, and chromosomes float freely
in the cytoplasm. The cell suspension is fixed and applied to a glass slide.
When the retainer dries, the cells and chromosomes are firmly attached to
the glass.
4. The drug is stained with nuclear dyes. There are methods of routine
and differential staining. At routine staining the drug is stained with azure-
eosin according to Romanovsky - Gimze. In this case, all chromosomes are
stained evenly along the entire length. Routine staining allows you to count
the number of chromosomes, divide them into groups and detect gross
chromosomal aberrations. For some diagnostic purposes (for example, to
detect numerous chromosome abnormalities), this method is quite
sufficient.
To obtain a more detailed picture of the structure of chromosomes and
accurate diagnosis of chromosomal aberration, various methods of
differential staining are used, in which chromosomes are stained unevenly
along the length.

Differential staining of chromosomes.

The most widely used G-color (from the English. Giemsa stain).
Chromosomes are pre-treated with proteases (trypsin) before staining
according to Romanowski-Gimse. Chromosomes after staining become
striped. They alternate dark and light stripes. Transverse stripes that
appear in the differential color are called segments. It is believed that dark
bands (G-bands) are areas of heterochromatin, and light (R-bands) are
areas of euchromatin. Usually up to 400 segments can be counted in a
haploid set. It is estimated that each segment contains about 8 million bp.
The alternation of dark and light bands (segments) is individual in each pair
of chromosomes. A form of representation of a stylized ideal karyotype with
a typical pattern of bands on each chromosome has been developed.
Schematically generalization of a karyotype with a graphic representation
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of individual chromosomes of a set with all their structural characteristics is
called an ideogram.
Study of metaphase chromosomes (differential staining with high
resolution). Today, methods have been developed for the manufacture of
metaphase plates, ie the separation is stopped at the stage of the
metaphase, when the chromosomes are not sufficiently condensed.
Prometaphase chromosomes are longer than chromosomes at the
metaphase stage. In the differential staining of metaphase chromosomes
can be considered from 550 to 850 segments. The segments observed in
the metaphase chromosomes can be divided into subsegments. This
method is used to diagnose microdeletions, microduplications and complex
chromosomal aberrations.

Molecular cytogenetic methods.

These are methods that combine traditional cytogenetic techniques with
molecular genetic technologies. The main method is fluorescent
hybridization in situ (FISH method).
The technique involves in situ hybridization (ie in the preparation, on a
glass slide) stained with fluorescent dyes DNA probes with metaphase or
interphase chromosomes.
A probe is a region of single-stranded DNA that is complementary to a
specific region of a gene or chromosome. Probes can be DNA sequences
isolated from the genome, artificially synthesized or cloned using bacterial
plasmids or other methods. For the FISH method, the probes are labeled
with biotin or digoxigenin, to which fluorescent dyes are then added.
Метод містить такі етапи:
1. Prepare a preparation of metaphase or pro-metaphase chromosomes.
2. The drug is treated with alkalis. This denatures DNA, that is, the
hydrogen bonds between the two strands of DNA are broken.
3. DNA probes are dripped on the glass. The probes connect to
complementary DNA chromosome sequences. There is a so-called
hybridization. Hybridization is the complementarity of nucleic acids isolated
from different sources (in this case, the patient's DNA is hybridized to the
probe's DNA).
4. The drug is washed from the excess probe. Hybridized probes remain
fixed on chromosomes. It is treated with fluorescent dyes that bind to biotin
or digoxigenin. Rhodamine (red glow) or fluorescein isothiocyanate (green
glow) can be used as dyes.
5. The drug is examined under a fluorescent microscope. The
chromosome regions where the hybridization took place and the probes are
located give a specific glow.
Currently, the FISH method is also used to study chromosomes in non-
dividing cells at the interphase stage.
In clinical genetics, the method is used for
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1) rapid diagnosis of chromosomal diseases associated with changes in
the number of chromosomes in the interphase nuclei,
2) diagnosis of microdeletions, microduplications and complex
chromosomal rearrangements, which are rarely detected using
conventional cytogenetic techniques.
Determination of sex chromatin.
This is an express method that allows you to determine the number of
sex chromosomes, but requires further karyotyping to confirm the
diagnosis.
Methods for determination of X-sex chromatin (Barr's body) and Y-sex
chromatin have been developed.
X-sex chromatin. Barr's bodies are a helical X chromosome. One of the
X chromosomes in females is inactivated and spiraled on the 16th-19th day
of embryonic development, and the other remains active. The helical X
chromosome is visible in the nuclei of somatic cells in the form of a dark,
well-colored lump.
Barr's bodies are found in epithelial cells of the buccal mucosa (buccal
scraping) or neutrophils.
In epithelial cells, sex chromatin lumps are located under the nuclear
membrane. In normal women, sex chromatin is found in more than 20% of
cells. In men, sex chromatin is normally absent.
Sex chromatin can also be detected in blood smears stained by
Romanowski-Gimse. In neutrophils, Barr bodies have the appearance of
drumsticks. Normally, in women drumsticks are found in 1-2% of
leukocytes, and in men there are no.
The method is used:
- for rapid diagnosis of chromosomal diseases associated with changes
in the number of X chromosomes; the number of X chromosomes per unit
is greater than the number of clumps of sex chromatin and is determined
by the formula: N = n +1,
where N is the number of X chromosomes; n is the number of lumps of
sex chromatin;
- as an express method of diagnosing sex in hermaphroditism;
- in forensic medicine to determine the sex of fragments of the human
corpse (Barr's bodies are well preserved in cartilage).
Y-sex chromatin. There is a method for determining Y-chromatin. Y-
chromatin is an intensely fluorescent region of the long arm of the Y
chromosome in the interphase nuclei. It can be identified in buccal
scraping, peripheral blood leukocytes. The drug is stained with fluorescent
dye acridine mustard. Under a fluorescent microscope, Y-chromatin is
detected in the cell nucleus as a bright spot with a diameter of 0.3–1.0 μm.
In men, one lump of Y-chromatin is normal.
The method is used for rapid diagnosis of Y polysomy syndrome.
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Chromosomal diseases.
Chromosomal diseases are inherited diseases caused by changes in the
number and structure of chromosomes. They can be divided into two
groups:
1. Diseases associated with changes in the number of autosomes.
They are characterized by multiple developmental disabilities, mental
retardation. Usually these diseases are diagnosed at birth.
2. Diseases associated with changes in the number of sex
chromosomes. Usually manifested by sexual dysfunction. Intelligence is
more often preserved.

Clinical and cytogenetic characteristics of major chromosomal diseases and

syndromes
Karyotype Frequen
Syndrome cy in the The main clinical symptoms
populati
on
Triploidy 69, ХХY Sporadi Increase in the mass and size of the placenta,
або 69, c cases focal pseudocystic degeneration of the
XXX chorionic villi. Hypopalasia at birth. Fatal
syndrome of multiple congenital malformations
Down'S 47,ХХ,+21 1:700–1 Mental retardation, muscular hypotension,
Syndrome або :800 brachycephaly, microcephaly, flat face,
47,ХY,+21 Mongoloid incision of the eye, macroglossia,
50% of heart defects, defects, etc. organs,
immunodeficiency. Some patients live up to
50-60 years.
Edwards'S 47,ХХ, +18 1:5000– Prenatal hypoplasia, single umbilical artery,
syndrome або 47,ХY, 1:7000 dolichocephaly, overhanging occiput,
+18 (70% of microgeny, specific flexion of the fingers,
patients rocking foot, multiple malformations of the
are girls internal organs, lethal syndrome
Syndrome 47,ХХ, +13 1:5000– Microcephaly, cleft lip and palate, polydactyly,
Patau або 1:7000 multiple birth defects, lethal syndrome
47,ХY, +13
"Cat's cry" 46,ХХ, 1:45000 Unusual screaming, reminiscent of cat
syndrome del5p- або –1:5000 meowing, microcephaly, antimongoloid incision
46,XY,del 0 of the eyes, hypertelorism, wide nose, defects
5p- of internal organs, mental retardation. Some
patients live more than 50 years.
Shereshevsky- 45,Х 1:3000– In newborns - lymphedema of the hands and
Turner syndrome 3500 feet, especially noticeable on the lower
girls extremities; hypotension, skin folds on the
neck. In older children - sexual infantilism,
primary amenorrhea, short stature, skin folds
on the neck, congenital malformations of the
cardiovascular, genitourinary and other
systems. Intelligence is usually normal.
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Polysomy X- More 1:1000 The clinical picture of trisomy X is variable -
syndrome frequent - from almost healthy fertile women to patients
("superwoman" trisomy X - 1:1200 with severe hypergonadotropic hypogonadism,
syndrome) 47, XXX, дівчато infertility, oligophrenia. At a tetrasomy X and a
Rarely к pentasomy X symptomatology, in 100%
tetrasomy - oligophrenia is more expressed. Craniofacial
48, XXXX dysmorphia, defects of teeth, skeleton and
and even genitals are described
less often
pentasomy
49, XXXX
Klinefelter's More 1:1000 At trisomies the variable clinic from easy forms
syndrome frequent boys with normal intelligence and fertility to heavy,
trisomy X - are followed by hypogenitalism,
47, XXX, hypogonadism, infertility. At tetrasomies and
Rarely pentasomies symptoms are always expressed.
tetrasomy - External signs: eunuchoid physique, elongated
48, XXXX distal extremities, gynecomastia, female
and even pattern baldness, hypogonadism.
less often
pentasomy
49, XXXX
Y-chromosome More 1:1000 Clinical symptoms range from almost normal
polysomy common men in physical and mental development to
syndrome trisomy 47, patients with mild mental retardation,
("superman" XYY, liquid propensity to criminal and even aggressive
syndrome) 48, XYYY, acts.
49, XYYYY

Prenatal diagnosis of chromosomal diseases.

Manifestation of chromosomal and genomic mutations begins during
embryonic development, so most chromosomal diseases can be diagnosed
before birth - prenatally.
Prenatal (antenatal) diagnosis of hereditary diseases involves
examination of all pregnant women with ultrasound (detecting
malformations) and determination of certain substances in the serum of
pregnant women, called maternal serum markers (in chromosomal
pathology in the child their content changes)
If the results of ultrasound and biochemical examination suggest
chromosomal disease in the fetus, invasive prenatal diagnosis is performed
- obtaining cells of the amniotic sac or fetus and their subsequent
cytogenetic study.
To obtain cells use:
 • Chorion biopsy — obtaining chorionic tissue. Chorion - villous shell.
It is formed during pregnancy from a trophoblast, so chorionic cells
have the same genotype as embryonic cells. It is recommended to
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spend at a gestational age of 10-14 weeks;

 • Placentocentesis — obtaining placental tissue, carried out from the
14th week of pregnancy;
 • Amniocentesis — obtaining amniotic fluid, which contains
exfoliated cells of the fetus and amnion. Early amniocentesis is
performed at 13-14 weeks, late - usually at 16-20 (preferably 16)
weeks of pregnancy;
 • Cordocentesis — taking blood from the umbilical cord under
ultrasound control through the anterior abdominal wall. Conducted
from the 20th week of pregnancy.

5. Materials on methodological support of the lesson.

6.1. Control materials for the preparatory stage of the lesson: questions, tasks, tests.
Test questions to check the initial level of knowledge of students

1. What are hereditary diseases? Name the groups of hereditary diseases.

2. What is the cytogenetic method of human genetics based on? To diagnose which
group of hereditary diseases is it used?
3. Classification of cytogenetic methods.
4. Stages of the karyotyping method. What is differential coloring?
5. The nature and mechanism of X-sex chromatin. What is B-chromatin?
6. What is the definition of sex chromatin?
7. Characteristics of karyotypes in major human chromosomal diseases, their
cytogenetic diagnosis.
8. What is prenatal diagnosis? The concept of invasive prenatal diagnosis.

1. Learn the rules of recording human karyotype in normal and various

chromosomal diseases resulting from genomic mutations

1. First indicate the total number of chromosomes.

For example: 46; 47.
2. Then, after the comma, the letters indicate the sex chromosomes.
For example: 46, XX; 47, ХХY.
3. The number (according to the Denver classification, 1960) of the extra
chromosome is indicated in parentheses with the sign "+".
For example: 47, XY (21+).
4. The karyotype of a human mosaic is indicated next to the oblique fraction sign
"/".
For example: 46, XX / 47, XX (18+).

2. Learn the rules of recording human karyotype in various chromosomal diseases

resulting from chromosomal aberrations

1. The arms of chromosomes are indicated by Latin symbols (p is short; q is long).

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2. Deletion is denoted as follows: 46, XX (5r-); 46, XY (5p-) or 46, XX, del (5p);
46, XY, del (5p).
3. Duplication is denoted as follows: 46, XX (13q +); 46, XY (13q +) or 46, XX,
dup (13q); 46, XY, dup (13q).

3. Examine the schematic image of the nuclei of epithelial cells of the buccal
scraping, find the X-sex chromatin body present on the inner membrane of the
nucleus, mark it. Find and mark the "drumstick" on the schematic image of the
neutrophil leukocyte

3. Solve test problems

1. Which method is a method of accurate diagnosis of chromosomal diseases?

A. Cytogenetic.
B. Dermatoglyphic.
C. DNA diagnostics.
D. Clinical and genealogical.
E. Specific biochemical diagnostics.

2. For the diagnosis of chromosomal diseases use all methods, except:

A. Karyotyping.
B. Determination of sex chromatin.
C. Biochemical.
D. Molecular cytogenetic.
E. FISH method

3. Karyotyping is one of the genetic methods. Phytohemagglutinin is used in the

manufacture of metaphase plates. What effect does it have on lymphocytes?
A. Stimulates cells to mitosis.
B. Destroys the spindle.
C. Stops mitosis in metaphase.
D. Stops mitosis in anaphase.
E. Causes swelling of chromosomes and cells.

4. Karyotyping is one of the genetic methods. Colchicine is used in the

manufacture of metaphase plates. How does it affect lymphocytes?
A. Stimulates cells to mitosis.
B. Causes swelling of the cell.
C. Stops mitosis in metaphase.
D. Stops mitosis in anaphase.
E. Causes swelling of chromosomes.

5. In women with mental retardation karyotype 48, XXXX. How many lumps of
sex chromatin can be found in a buccal scraper?
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A. 0.
B. 1.
C. 2.
D. 3.
E. 4.

6. In a man with karyotype 48, XYYY number of Barr's bodies in the scraping
of the mucous membrane of the cheek:
A. 0.
B. 1.
C. 2.
D. 3.
E. 4.

6.2. Materials of methodical support of the main stage of the lesson:

professional algorithms, orientation maps for the formation of practical skills and
abilities, educational tasks.

Professional algorithm:
To analyze the photokaryograms of patients and determine chromosomal disease
requires:
1. Recall the principles of construction of a normal karyotype. To do this, it is
necessary to remember that chromosomes are classified according to the size
and shape of chromosomes.

The groups are denoted by letters of the English alphabet from A to G. The
groups are clearly different from each other. Sex chromosomes are denoted by the
Latin letters X and Y and have autosomes at the end of the layout.
Group A (1, 2, 3 pairs) - the longest chromosomes, 1st and 3rd pairs -
metacentric, 2nd - submetacentric. Absolute length from 11 to 8.3 microns.
Group B (pairs 4 and 5) - long submetacentric chromosomes. They do not differ
from each other without differential color. The absolute length is 7.7 microns.
Group C (6–12 pairs) - chromosomes of medium size, submetacentric. Absolute
length - from 7.2 to 5.8 microns. With standard (routine) staining, the X
chromosome cannot be distinguished from other chromosomes in this group. It is
similar in size to the chromosomes of the 6th and 7th pairs.
Group D (13–15 pairs) are middle acrocentric chromosomes, very different in
shape from all other human chromosomes. All three pairs on the short shoulder
contain a secondary constriction and companions. The length of the proximal parts
of the short shoulders varies, the satellites may be absent, and sometimes may be
very large, may fluoresce brightly, and may not give fluorescence. The absolute
length is 4.2 microns.
Group E (16-18 pairs). Relatively short submetacentric chromosomes. The
absolute length is 3.6–3.2 μm.
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Group F (19–20 pairs) are small metacentric chromosomes. In drugs with
routine staining, they look the same, but with differential staining differ sharply.
The absolute length is 2.9 microns.
Group G (21–22 pairs) are the smallest acrocentric chromosomes. They have a
satellite on their short shoulders. The variability of their short shoulders is as
significant as in the chromosomes of group D. The absolute length is 2.3 μm.
Y-chromosome is a small acrocentric chromosome 2.8 μm long. Usually
(but not always) more than the chromosomes of group G. The chromatids of
her long arm, as a rule, lie parallel to each other. This distinguishes it from
group G chromosomes, in which the chromatids of the long arms form a wide
angle. Sometimes has a secondary constriction in the long shoulder.
X chromosome - submetacentric, 6.8 μm long. The structure is similar to
chromosomes of group C, differs in differential color.

1. Carefully look at the photokaryogram, pay attention to the number of

chromosomes of each pair, the uniformity of both chromosomes of the
homologous pair of autosomes, the number of sex chromosomes. Notice whether
the male or female karyotype is represented. If differences from the normal
karyotype are found, determine to which group the wrong chromosome belongs, its
number according to the chromosome classification.

2. Based on the knowledge of mutations that cause major chromosomal diseases,

determine chromosomal disease.

3. Based on the rules of karyotype recording, write the karyotype. Note the male or
female patient whose karyotype is represented.

Algorithm for determining sex chromatin in buccal scraping:

1. After pre-rinsing the mouth with a disposable dental spatula with the
right hand take a scrape of the epithelium of the inner surface of the cheek
near the molars. The left hand supports the cheek from the outside.
2. The scraper is applied in an even layer on a glass slide, 1 - 2 drops of
1% acetoarcein in glacial acetic acid are added, stained for 2 min, then
covered with a cover glass. Excess paint is removed with filter paper.
3. Counting of sex chromatin bodies is performed under immersion in
round or oval nuclei with intact nuclear membrane. The content of sex
chromatin is expressed as a percentage. To do this, find 100 cell nuclei,
take into account the number of nuclei containing sex chromatin.
4. Carry out the relationship between the number of Barr cells in the nuclei
of cells by the formula: N = n +1, where N is the number of X
chromosomes; n is the number of lumps of sex chromatin. Pay attention to
the phenotypic sex of the person whose cells are being studied.
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Educational tasks

1. Fill in the table on the main chromosomal diseases of man. Choose which
cytogenetic methods can be used in the diagnosis of these inherited diseases.

Diagnostic method Research results

Condition / Mutation The number
syndrome type Sex Karyotypes of Barr's
Karyotyping
chromatin are possible calves in the
nucleus
Healthy people

Diseases caused by autosomal abnormalities

Down'S syndrome
Edward's
syndrome
Patau's syndrome
Cat Cry Syndrome
Diseases caused by abnormalities of heterochromosomes
Shereshevsky-
Turner syndrome
Superwoman
syndrome
(polysomy-X)
Klinefelter's
syndrome
Superman
Syndrome
(Polysomy-Y)

1. Analyze photokaryograms of patients with various chromosomal diseases.

Identify the disease, write down the karyotype.
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2. Determine sex chromatin in buccal scraping cells according to a professional
algorithm. Determine the number of sex X chromosomes. (or analyze photographs
of the buccal epithelium with different numbers of Barr's bodies). Write the
karyotype.

Control materials for the final stage of the lesson

1. Fill in the table of chromosomal diseases. Using textbooks and manuals,
independently write down possible karyotypes and the characteristic of the
main phenotypic displays at various chromosomal diseases of the person.

Syndromes Karyotype Frequency Phenotype characteristics

(s)
Diseases caused by autosomal abnormalities
Down'S syndrome 1:700
Edward's syndrome 1:6000
Patau's syndrome 1:7000
Cat Cry Syndrome 1:50000
Diseases caused by heterochromosome abnormalities
Shereshevsky- 1:3000
Turner syndrome
Superwoman 1:1100
syndrome
(polysomy-X)
Klinefelter's 1:900
syndrome
Superman 1:1000
Syndrome
(Polysomy-Y)

Solve situational problems.

1. The staff of the pre-trial detention center sent a tall man with antisocial
behavior to the medical and genetic center for examination. Luminescent
microscopy of Caspersson-stained acrychin-mustard-stained cells revealed two
very green glowing bodies. What research method was used? What syndrome
can be predicted? Write down the karyotype. What method should be used to
confirm the diagnosis of chromosomal disease?
2. 2. An eight-month-old girl was diagnosed with microcephaly, nonunion of
the upper lip and palate, congenital malformations of the eyes, cardiovascular
system, etc. Karyotyping revealed 47 chromosomes, and the 13th chromosome
of group D is superfluous. Which syndrome can be established on the basis of
phenotypic manifestations and karyotyping data? Write down the karyotype. Is
it necessary to determine sex chromatin?
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3. A 28-year-old woman consulted a doctor about infertility. The examination
revealed underdevelopment of the ovaries and uterus, menstrual irregularities.
Examination of buccal epithelial cells in the nuclei of most of them revealed
two Barr bodies, in the nuclei of neutrophilic leukocytes - "drumsticks". What
research method was used? What preliminary diagnosis can this woman be
given? Write down the karyotype. What method should be used to confirm the
diagnosis of chromosomal disease?
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