human genetic disorder

1. By,
Pillai Aswathy viswanath
PG 1 Botany
St. Thomas college
kozhencherry

2.  Gene is the unit for genetic information.
 Human being has about 30,000 genes
 Every gene has a different function,
controlling all kinds of biological activities
including embryological development, fetal
growth, metabolism, personality, cognition

3.  They are located on
DNA strands which
make up the
chromosomes.
 Chromosomes are the
genetic material
within a cell nucleus.

4.  A genetic disease or disorder is the result of
changes, or mutations, in an individual’s
DNA
 A mutation is a change in the letters (DNA
sequence) that make up a gene.
 Most people have the concept that a
genetic disease must be one that is
transmitted from one generation to the
next.

5.  Actually this is not totally correct. In
medicine, a genetic disease refers to one
that is caused by abnormalities of the
genetic material at the stage of germ cell or
early embryo.
 So genetic disorder is an illness caused by
one or more abnormalities in the genome,
especially a condition that is present from
birth (congenital).

6.  Each cell in the human
body contains 23 pairs of
chromosomes
 The normal human
chromosome
complement consists of
46 chromosomes
comprising 22
morphologically
different pairs of
autosomes and one pair
of sex chromosomes.

7.  Each chromosome is made up of many genes
 These genes make all the proteins in the body,
which promote development and growth, and
carry out all body functions.
 When one or more of these genes or
chromosomes are missing or mutated, or if
extra chromosomes are present, the proteins
may not get made, may be made incorrectly,
or too many may be made.

8.  Any of these situations can cause abnormal
development and growth and can result in
a genetic disorders.
 Sometimes these abnormal genes or
chromosomes are passed down from a
parent, and sometimes they occur
spontaneously without reason.

9.  Genetic disorder can be divided into
three categories:
Single gene
disorders
.
Chromosomal
disorders
Complex
disorders

10.  Single-gene disorders, where a mutation
affects one gene.
 Chromosomal disorders, where
chromosomes (or parts of chromosomes) are
missing or changed.
 Complex disorders, where there are
mutations in two or more genes. Often your
lifestyle and environment also play a role.

11.  Down Syndrome
 Edward Syndrome
 Patau Syndrome
 Klinefelter Syndrome
 Turner Syndrome
 Sickle Cell Disease

12.  Haemophilia
 Color Blindness
 Cystic Fibrosis
 Huntington’s disease
 Chronic myelogenous leukemia
 Lesch-Nyhan syndrome

13.  It is an autosomal abnormality
due to one extra chromosome
in the 21st pair of autosome.
 Hence this syndrome is called
trisomy-21
 Patients will have 47
chromosomes instead of 46
chromosomes.
 They resemble to Mongolian
 Also known as mongolism

15.  Upward slant to eyes.
 Small ears that fold over at the top.
 Small, flattened nose.
 Small mouth, making tongue appear large.
 Short neck.
 Small hands with short fingers.
 Low muscle tone.

16.  Looseness of joints.
 Small skin folds at the
inner corners of the eyes.
 Excessive space between
first and second toe.
 In addition, down
syndrome always involves
some degree of mental
retardation, from mild to
severe.

17.  Edwards syndrome is a chromosomal
abnormality characterized by the presence of
an extra copy of genetic material on the 18th
chromosome, either in whole (trisomy 18) or
in part
 It is named after John Hilton Edwards, who
first described the syndrome in 1960.
 It is the second most
common autosomal trisomy, after Down
syndrome, that carries to term.

19.  Mental and physical
retardation
 Skull and facial
abnormalities
 Defects in all organ
systems
 Poor muscle tone
 Average life expectancy: 2-
4 month

20.  Patau's syndrome is the result
of trisomy 13, meaning each cell
in the body has three copies of
chromosome 13 instead of the
usual two.
 Most cases of Patau syndrome are
not inherited, but occur as
random events during the
formation of reproductive cells
(eggs and sperm).

22.  Individuals with trisomy
13 often have heart
defects, brain or spinal
cord abnormalities, very
small or poorly developed
eyes (microphthalmia),
extra fingers or toes, an
opening in the lip (a cleft
lip) with or without an
opening in the roof of the
mouth (a cleft palate), and
weak muscle tone
(hypotonia).

23.  Due to the presence of several
life-threatening medical
problems, many infants with
trisomy 13 die within their
first days or weeks of life.
 Only five percent to 10
percent of children with this
condition live past their first
year.

24.  This is the most common sex
chromosomal abnormality
 It was first identified in 1942 by
klinefelter
 Patients will have 47 chromosomes
instead of 46 chromosomes.
 That is 44 autosomes and 2X
chromosomes along with a Y
chromosomes

26.  Phenotypically the patients are male but with
rudimentary sex organs
 They shows some feminine characters
 Development of breast tissue normally seen
in females.
 Little body hair is present, and such person
are typically tall, have small testes.
 Infertility results from absent sperm.
 Evidence of mental retardation may or may
not be present.

27.  It is a sex chromosomal abnormality in
women.
 first described in 1938 by Henry H
Turner
 The patients have only 45 chromosomes
 Karyotype analysis shows that such
females have 44 autosomes but they
have only one X chromosomes

29.  Turner syndrome is associated with
underdeveloped ovaries, short stature,
webbed, and is only in women.
 Bull neck, and broad chest. Individuals are
sterile, and lack expected secondary sexual
characteristics.
 Absence of menstrual cycle
 Such women are prone to heart diseases,
hypothyroidism, diabetes and visual and
auditory problems.

30.  Sickle cell disease or sickle cell anemia is a
blood disorder
 Sickle cell anemia is one type of anemia.
 Anemia is a condition in which a person’s
blood has a lower than normal number of red
blood cells, or the red blood cells don’t have
enough hemoglobin.
 Hemoglobin is an iron-rich protein that gives
blood its red color and carries oxygen from
the lungs to the rest of the body.

31.  A serious condition in which
red blood cells can become
sickle-shaped
 Normal red blood cells are
smooth and round. They
move easily through blood
vessels to carry oxygen to all
parts of the body.
 Sickle-shaped cells don’t
move easily through blood.
They’re stiff and sticky and
tend to form clumps and get
stuck in blood vessels.

32.  The clumps of sickle cell block blood flow in the
blood vessels
 Blocked blood vessel can cause pain, serious
infection, and organ damage.

33.  Normal red blood cells live about 120 days in
the bloodstream and then die.
 In sickle cell anemia, the abnormal sickle
cells usually die after only about 10 to 20
days.
 The bone marrow can't make new red blood
cells fast enough to replace the dying ones.
 Sickle cell anemia is an inherited, lifelong
disease. People who have the disease are born
with it.

34.  If one parent has sickle cell
anaemia (HbSS) and the
other is completely
unaffected (HbAA) then all
the children will have sickle
cell trait.
 None will have sickle cell
anemia.
 The parent who has sickle cell
anemia (HbSS) can only pass
the sickle hemoglobin gene
to each of their children.

35.  If both parents have sickle cell
trait (HbAS) there is a one in four
(25%) chance that any given child
could be born with sickle cell
anemia.
 There is also a one in four chance
that any given child could be
completely unaffected.
 There is a one in two (50%)
chance that any given child will
get the sickle cell trait.

36.  Haemophilia is commonly called bleeder’s
diseases
 This is a recessive X-linked genetic disorder
 Lethal recessive genes located on the X
chromosomes
 bodies of individuals lose the ability to
coagulate blood or blood clotting.
 As the mutation is caused in X chromosome
and the condition is recessive, the females are
carriers and males suffer from the symptoms
of haemophilia.

37.  The most common type of hemophilia is
called hemophilia A. This means the person
does not have enough clotting factor VIII
(factor eight).
 A less common type is hemophilia B. This
person does not have enough clotting factor
IX (factor nine).
 The result is the same for people with
hemophilia A and B: they both bleed for a
longer time than normal.

38.  Color blindness means that
you have trouble
seeing red, green, or blue
or a mix of these colors.
 Color blindness is also
called a color vision
problem.
 This disease consists of
the inability to
differentiate between reds
and greens.

39.  Most color vision problems are inherited
(genetic) and are present at birth.
 Colorblindness is caused by the X-linked
gene.
 Males are usually affected because they only
need one X, where females need both.
 Color blindness is caused by a defect in the
retina or in other nerve portions of the eye

40.  People usually have three types of cone
cells in the eye.
 Each type senses either red, green, or blue
light.
 You see color when your cone cells sense
different amounts of these three basic colors.
 The highest concentration of cone cells are
found in the macula, which is the central part
of the retina

42.  Inherited color
blindness happens
when you don't have
one of these types of
cone cells or they
don't work right.
 You may not see one
of these three basic
colors, or you may see
a different shade of
that color or a
different color.
Weak green cone
Weak red cone

43.  You may be able to see some colors but not
others. For instance, you may not be able to tell
the difference between some reds and greens but
can see blue and yellow easily.
 You may see many colors, so you may not know
that you see color differently from others.
 You may only be able to see a few shades of
color, while most people can see thousands of
colors.
 In rare cases, some people see only black, white,
and gray.

44.  Cystic fibrosis is an autosomal-recessive genetic
disorder
 It is caused by mutations in the CFTR
(cystic fibrosis transmembrane regulator) gene.
 The defective gene, CFTR, was identified in 1989
and mapped to the long arm of chromosome 7
 The CFTR gene normally creates a protein that
moves salt and water out of a cell.
 If the CFTR gene is defective, it results in a
build-up of thick, sticky mucus in the body's
tubes and passageways.

45.  CF primarily affects the
lungs and digestive
system and makes a child
more vulnerable to
repeated lung infections.
 These thick secretions also
obstruct the pancreas,
preventing digestive
enzymes from reaching
the intestines to help
break down and absorb
food.

47.  Abnormalities in the glands that produce
sweat and mucus, and may cause a loss of salt.
This can cause imbalance of blood minerals,
abnormal heart rhythms, and, possibly,
shock.
 Thick mucus in the lungs and intestines can
cause malnutrition, poor growth, frequent
respiratory infections, breathing difficulties,
and/or lung disease.

48.  Sinusitis
 clubbing of fingers and toes - a condition
marked by the ends of the fingers and toes
become enlarged; more prevalent in the
fingers.
 hemoptysis - coughing blood.
 cor pulmonale - enlargement of right side of
heart.
 abdominal pain
 gas in the intestines
 liver disease
 diabetes
 pancreatitis

49.  Huntington disease is a progressive brain
disorder that causes uncontrolled movements,
emotional problems, and loss of thinking ability
 The disease is also known as Huntington's
chorea.
 Chorea means "dance-like movements" and
refers to the uncontrolled motions often
associated with the disease.
 Having a parent with Huntington's is the risk
factor.
 A child of an affected parent has a 50% chance of
inheriting the disease

50.  Mutations in the HTT gene
cause Huntington disease.
 The HTT gene provides
instructions for making a
protein called huntingtin.
 Although the function of
this protein is unknown, it
appears to play an important
role in nerve cells (neurons)
in the brain.
 The HTT mutation that
causes Huntington disease
involves a DNA segment
known as a CAG
trinucleotide repeat

51.  An increase in the size of the CAG segment
leads to the production of an abnormally long
version of the huntingtin protein.
 The elongated protein is cut into smaller,
toxic fragments that bind together and
accumulate in neurons, disrupting the normal
functions of these cells.
 The dysfunction and eventual death of
neurons in certain areas of the brain underlie
the signs and symptoms of Huntington
disease.

52.  Chronic myelogenous (or
myeloid) leukemia (CML), also
known as chronic granulocytic
leukemia (CGL).
 Chronic myeloid leukaemia
(CML) is a type cancer that
affects the blood and bone
marrow.
 In CML the bone marrow
produces too many white cells,
called granulocytes.

53.  More than 90% of cases are
due to a gene abnormality
caused when two
chromosomes swap sections
with each other.
 There are 23 chromosomes in
humans, and in patients with
chronic myelogenous
leukemia chromosomes 9 and
22 within blood cells
exchange bits of genetic
material to form a
Philadelphia chromosome

55.  The new gene on this chromosome makes a
protein called tyrosine kinase that allows
white blood cells to grow out of control;
 moreover, these abnormal white blood cells
tend not to become old and die.
 The bone marrow, where red blood cells, white
blood cells, and platelets are made, becomes
filled with white blood cells crowding out the
normal cells and damaging the bone marrow
itself.
 This can impair the ability of the bone
marrow to manufacture normal amounts of
blood cells.

56.  Can occur as exposures to radiation,
chemicals, etc
 Known from 1981 or before that Benzene (a
byproduct of the use of laser printers and
copy machines) caused the mutation leading
to CML in humans
 Not enough has been done to protect
employees who work in the presence of
Benzene

57.  Bone and joint pain may occur as the bone
marrow pressure increases due to an excess
build-up of white blood cells.
 Fatigue may be due to anemia because not
enough red blood cells are being produced
and bleeding can occur if not enough
platelets are being manufactured.
 In some patients with chronic myelogenous
leukemia their bone marrow makes too many
platelets and they can develop abnormal
blood clotting, which can cause strokes.

58.  In chronic myelogenous leukemia there are
too many white blood cells, but these white
blood cells tend not to function properly and
their ability to fight infection is
compromised, which leads to an increased
risk of infection.
 The increased numbers of white blood cells
spill out of the bone marrow and start
circulating in the blood stream and eventually
become trapped in the spleen, causing it to
enlarge.

59.  It is an X-linked recessive disorder
which causes deficiency of the
enzyme hypoxanthine-guanine
phosphoribosyltransferase (HPRT).
 Lack of HPRT leads to
accumulation of uric acid in body,
which leads to gout and kidney
problems, poor muscle control and
mental retardation of moderate
degree.
 A striking feature of this disorder
is a child biting his lips and
fingers.

60.  This self mutilating behavior appears in
second year of a child's life.
 Other than these features, an individual
suffering from this disorder shows facial
grimacing.
 This disorder is alternatively also known as
Nyhan's syndrome, Juvenile gout and
Kelley-Seegmiller syndrome.

61.  John B Jenkins (1990).Human Genetics
Harper and Row,Publishers,New York
 http://www.buzzle.com/articles/genetic-
disorders-in-humans.html
 www.google.com, wikipedia.org
 http://www.diseaseinfosearch.org/
 www.webmd.com/eye-health/tc/color-
blindness-topic-overview
 www.britannica.com/EBchecked/topic/228874/h
uman-genetic-disease

62. By,Pillai Aswathy Viswanath