PRESIDENCY SCHOOL

MANGALORE

PHYSICS INVESTIGATORY
PROJECT ON

Chromosomal Disorders
SUBMITTED BY: RAYYAN SYED
SUBMITTED TO:
REGISTRATION NO:

1
 PRESIDENCY SCHOOL
CERTIFICATE
SUBJECT:
DATE:
BOARD ROLL NO.:
THIS IS TO CERTIFY THAT THIS PROJECT HAS BEEN
COMPLETED BY___________________________________OF
GRADE _____________ SEC ___________________ FOR THE
YEAR_____________________.

_______________________ ______________________
TEACHER IN-CHARGE EXTERNAL EXAMINER

________________________ ___________________________
PRINCIPAL SIGNATURE SEAL OF THE INSTITUTION

2
 ACKNOWLEDGEMENT
I WARMLY ACKNOWLEDGE THE CONTINOUS
ENCOURAGEMENT AND TIMELY SUGGESTION
BY OUR PRINCIPAL MR. TANGADURAI. I AM
INDEBTED TO MRS.RASHMITHASHETTY FOR
HER CONSTANT SUPERVISION, PROVIDING
NECESSARY INFORMATION AND HELPING US IN
COMPLETING THE PROJECT. I WOULD LIKE TO
EXPRESS MY GRATITUDE TO HER FOR HER CO-
OPERATION AND ENCOURAGEMENT.

3
 INDEX
SL NO. TOPIC PAGE NO.

1. WHAT 1

2. 2

3. 3-11

4. 12

5. R 13

6. T 14

7. 16

8. 17

9. 18-19

10. 20

4
What is a chromosomal disorder?
A chromosomal disorder, anomaly, aberration, or mutation is a missing,
extra, or irregular portion of chromosomal DNA. It can be from a typical
number of chromosomes or a structural abnormality in one or more
chromosomes. Chromosome mutation was formerly used in a strict
sense to mean a change in a chromosomal segment, involving more than
one gene. The term "karyotype" refers to the full set of chromosomes
from an individual; this can be compared to a "normal" karyotype for the
species via genetic testing. A chromosome anomaly may be detected or
confirmed in this manner. Chromosome anomalies usually occur when
there is an error in cell division following meiosis or mitosis. There are
many types of chromosome anomalies. They can be organized into two
basic groups, numerical and structural anomalies

Inheritance
Most chromosome abnormalities occur as an accident in the egg cell or
sperm, and therefore the anomaly is present in every cell of the body.
Some anomalies, however, can happen after conception, resulting in
Mosaicism (where some cells have the anomaly and some do not).
Chromosome anomalies can be inherited from a parent or be "de novo".
This is why chromosome studies are often performed on parents when a
child is found to have an anomaly. If the parents do not possess the
abnormality it was not initially inherited; however it may be transmitted
to subsequent generations.

5
Numerical disorders
Aneuploidy is a chromosomal mutation in which there is one or more
extra chromosomes, or one or more fewer chromosomes. In humans, the
genetic disorders Down syndrome and Turner's syndrome are examples
of aneuploidy. Individuals with Down syndrome have three copies of
chromosome 21, so their genomes contain 47 chromosomes rather than
the usual 46. Individuals with Turner syndrome have only one sex
chromosome, which is the X-chromosome, so their genomes contain 45
chromosomes.

Polyploidy is a chromosomal mutation in which a cell has entire extra

sets of chromosomes. Instead of being diploid, in which the cell contains
two sets of chromosomes, it may be triploid (three sets of
chromosomes), or tetraploid (four sets of chromosomes). Polyploidy is
common in plants, and plant growers may exploit this fact to produce
plants with flowers having double petals. Polyploidy is generally lethal
in animals.

6
Structural abnormalities
When the chromosome's structure is altered, this can take several forms:
Deletions: A portion of the chromosome is missing or deleted. Known
disorders in humans include Wolf-Hirschhorn syndrome, which is
caused by partial deletion of the short arm of chromosome 4; and
Jacobsen syndrome, also called the terminal 11q deletion disorder.
Duplications: A portion of the chromosome is duplicated, resulting in
extra genetic material. Known human disorders include Charcot-Marie-
Tooth disease type 1A, which may be caused by duplication of the gene
encoding peripheral myelin protein 22 (PMP22) on chromosome 17.
Translocations: A portion of one chromosome is transferred to another
chromosome. There are two main types of translocations:
Reciprocal translocation: Segments from two different chromosomes
have been exchanged.
Robertsonian translocation: An entire chromosome has attached to
another at the centromere - in humans these only occur with
chromosomes 13, 14, 15, 21, and 22.
Inversions: A portion of the chromosome has broken off, turned upside
down, and reattached, therefore the genetic material is inverted.
Insertions: A portion of one chromosome has been deleted from its
normal place and inserted into another chromosome.
Rings: A portion of a chromosome has broken off and formed a circle or
ring. This can happen with or without loss of genetic material.
Isochromosome: Formed by the mirror image copy of a chromosome
segment including the centromere.

7
Different Types of Chromosomal Disorders
1) Turner Syndrome
Turner syndrome (TS), also known 45,X, or 45,X0, is a genetic
condition in which a female is partly or completely missing an X
chromosome. Signs and symptoms vary among those affected. Often, a
short and webbed neck, low-set ears, low hairline at the back of the
neck, short stature, and swollen hands and feet are seen at birth.
Typically, they develop menstrual periods and breasts only with
hormone treatment, and are unable to have children without reproductive
technology. Heart defects, diabetes, and low thyroid hormone occur
more frequently. Most people with TS have normal intelligence. Many
have troubles with spatial visualization that may be needed for
mathematics. Vision and hearing problems occur more often.
Turner syndrome is not usually inherited from a person's parents. No
environmental risks are known, and the mother's age does not play a
role. Turner syndrome is due to a chromosomal abnormality in which all
or part of one of the X chromosomes is missing or altered. While most
people have 46 chromosomes, people with TS usually have 45. The
chromosomal abnormality may be present in just some cells in which
case it is known as TS with mosaicism. In these cases, the symptoms are
usually fewer and possibly none occur at all. Diagnosis is based on
physical signs and genetic testing.
No cure for Turner syndrome is known. Treatment may help with
symptoms. Human growth hormone injections during childhood may
increase adult height. Estrogen replacement therapy can promote
development of the breasts and hips. Medical care is often required to
manage other health problems with which TS is associated.

8
Turner syndrome occurs in between one in 2,000 and one in 5,000
females at birth. All regions of the world and cultures are affected about
equally. Generally people with TS have a shorter life expectancy, mostly
due to heart problems and diabetes. Henry Turner first described the
condition in 1938. In 1964, it was determined to be due to a
chromosomal abnormality.

Signs and symptoms

Of the following common symptoms of Turner syndrome, an individual
may have any combination of symptoms and is unlikely to have all
symptoms.

 Short stature
 Lymphedema (swelling) of the hands and feet of a newborn
 Broad chest (shield chest) and widely spaced nipples
 Low posterior hairline
 Low-set ears
 Reproductive sterility
 Rudimentary ovaries gonadal streak (underdeveloped gonadal
structures that later become fibrotic)
 Amenorrhoea, the absence of a menstrual period
 Increased weight, obesity
 Shortened metacarpal IV
 Small fingernails
 Characteristic facial features
 Webbed neck from cystic hygroma in infancy
 Aortic valve stenosis
 Coarctation of the aorta

9
  Bicuspid aortic valve (most common cardiac problem)
 Horseshoe kidney
 Visual impairments – sclera, cornea, glaucoma, etc.
 Ear infections and hearing loss
 High waist-to-hip ratio (the hips are not much bigger than the
waist)
Attention deficit hyperactivity disorder (problems with concentration,
memory, attention with hyperactivity seen mostly in childhood and
adolescence)
Nonverbal learning disability (problems with maths, social skills, and
spatial relations)
Other features may include a small lower jaw (micrognathia), cubitus
valgus, soft upturned nails, palmar crease, and drooping eyelids. Less
common are pigmented moles, hearing loss, and a high-arch palate
(narrow maxilla). Turner syndrome manifests itself differently in each
female affected by the condition; therefore, no two individuals share the
same features.
While most of the physical findings are harmless, significant medical
problems can be associated with the syndrome. Most of these significant
conditions are treatable with surgery and medication.

10
 2) Down Syndrome
Down syndrome (DS or DNS), also known as trisomy 21, is a genetic
disorder caused by the presence of all or part of a third copy of
chromosome 21. It is usually associated with physical growth delays,
mild to moderate intellectual disability, and characteristic facial features.
The average IQ of a young adult with Down syndrome is 50, equivalent
to the mental ability of an 8- or 9-year-old child, but this can vary
widely.
The parents of the affected individual are usually genetically normal.
The probability increases from less than 0.1% in 20-year-old mothers to
3% in those of age 45. The extra chromosome is believed to occur by
chance, with no known behavioral activity or environmental factor that
changes the probability. Down syndrome can be identified during
pregnancy by prenatal screening followed by diagnostic testing or after
birth by direct observation and genetic testing. Since the introduction of
screening, pregnancies with the diagnosis are often terminated.Regular
screening for health problems common in Down syndrome is
recommended throughout the person's life.
There is no cure for Down syndrome. Education and proper care have
been shown to improve quality of life. Some children with Down
syndrome are educated in typical school classes, while others require
more specialized education. Some individuals with Down syndrome
graduate from high school, and a few attend post-secondary education.
In adulthood, about 20% in the United States do paid work in some
capacity, with many requiring a sheltered work environment. Support in
financial and legal matters is often needed. Life expectancy is around 50
to 60 years in the developed world with proper health care.

11
Down syndrome is one of the most common chromosome abnormalities
in humans.[8] It occurs in about one per 1,000 babies born each year. In
2015, Down syndrome was present in 5.4 million individuals globally
and resulted in 27,000 deaths, down from 43,000 deaths in 1990. It is
named after John Langdon Down, a British doctor who fully described
the syndrome in 1866. Some aspects of the condition were described
earlier by Jean-Étienne Dominique Esquirol in 1838 and Édouard Séguin
in 1844. The genetic cause of Down syndrome was discovered in 1959.

Signs and symptoms

Those with Down syndrome nearly always have physical and intellectual
disabilities. As adults, their mental abilities are typically similar to those
of an 8- or 9-year-old. They also typically have poor immune function
and generally reach developmental milestones at a later age. They have
an increased risk of a number of other health problems, including
congenital heart defect, epilepsy, leukemia, thyroid diseases, and mental
disorders.

12
 3) Edwards Syndrome
Edwards syndrome, also known as trisomy 18, is a genetic disorder
caused by a third copy of all or part of chromosome 18. Many parts of
the body are affected. Babies are often born small and have heart
defects. Other features include a small head, small jaw, clenched fists
with overlapping fingers, and severe intellectual disability.
Most cases of Edwards syndrome occur due to problems during the
formation of the reproductive cells or during early development. The
rate of disease increases with the mother's age. Rarely cases may be
inherited from a person's parents. Occasionally not all cells have the
extra chromosome, known as mosaic trisomy, and symptoms in these
cases may be less severe. Ultrasound can increase suspicion for the
condition, which can be confirmed by amniocentesis.
Treatment is supportive. After having one child with the condition, the
risk of having a second is typically around one percent. It is the second-
most frequent condition due to a third chromosome at birth, after Down
syndrome.
Edwards syndrome occurs in around one in 5,000 live births. Some
studies suggest that more babies that survive to birth are female. Many
of those affected die before birth. Survival beyond a year of life is
around 5–10%. It is named after John Hilton Edwards, who first
described the syndrome in 1960.

Signs and symptoms

Children born with Edwards syndrome may have some or all of these
characteristics: kidney malformations, structural heart defects at birth
(i.e., ventricular septal defect, atrial septal defect, patent ductus

13
arteriosus), intestines protruding outside the body (omphalocele),
esophageal atresia, intellectual disability, developmental delays, growth
deficiency, feeding difficulties, breathing difficulties, and arthrogryposis
(a muscle disorder that causes multiple joint contractures at birth).
Some physical malformations associated with Edwards syndrome
include small head (microcephaly) accompanied by a prominent back
portion of the head (occiput), low-set, malformed ears, abnormally small
jaw (micrognathia), cleft lip/cleft palate, upturned nose, narrow eyelid
folds (palpebral fissures), widely spaced eyes (ocular hypertelorism),
drooping of the upper eyelids (ptosis), a short breast bone, clenched
hands, choroid plexus cysts, underdeveloped thumbs and/or nails, absent
radius, webbing of the second and third toes, clubfoot or rocker bottom
feet, and in males, undescended testicles.
In utero, the most common characteristic is cardiac anomalies, followed
by central nervous system anomalies such as head shape abnormalities.
The most common intracranial anomaly is the presence of choroid
plexus cysts, which are pockets of fluid on the brain. These are not
problematic in themselves, but their presence may be a marker for
trisomy 18. Sometimes, excess amniotic fluid or polyhydramnios is
exhibited.

14
 4) Klinefelter Syndrome
Klinefelter syndrome (KS), also known as 47,XXY or XXY, is the set of
symptoms that result from two or more X chromosomes in males. The
primary features are infertility and small testicles. Often, symptoms may
be subtle and many people do not realize they are affected. Sometimes,
symptoms are more prominent and may include weaker muscles, greater
height, poor coordination, less body hair, breast growth, and less interest
in sex. Often it is only at puberty that these symptoms are noticed.
Intelligence is usually normal; however, reading difficulties and
problems with speech are more common. Symptoms are typically more
severe if three or more X chromosomes are present (48,XXXY
syndrome or 49,XXXXY syndrome).
Klinefelter syndrome usually occurs randomly. An older mother may
have a slightly increased risk of a child with KS. The condition is not
typically inherited from one's parents. The underlying mechanisms
involves at least one extra X chromosome in addition to a Y
chromosome such that the total chromosome number is 47 or more
rather than the usual 46. KS is diagnosed by the genetic test known as a
karyotype.
While no cure is known, a number of treatments may help. Physical
therapy, speech and language therapy, counselling, and adjustments of
teaching methods may be useful. Testosterone replacement may be used
in those who have significantly lower levels. Enlarged breasts may be
removed by surgery. About half of affected males have a chance of
fathering children with the help of assisted reproductive technology, but
this is expensive and not risk free. Males appear to have a higher risk of
breast cancer than typical, but still lower than that of females. People
with the condition have a nearly normal life expectancy.

15
Klinefelter syndrome is one of the most common chromosomal
disorders, occurring in one to two per 1,000 live male births. It is named
after the endocrinologist Harry Klinefelter, who identified the condition
in the 1940s. In 1956, identification of the extra X chromosome was first
noticed. Mice can also have the XXY syndrome, making them a useful
research model.

Signs and symptoms

As babies and children, XXY males may have weaker muscles and
reduced strength. As they grow older, they tend to become taller than
average. They may have less muscle control and coordination than other
boys of their age.
During puberty, the physical traits of the syndrome become more
evident; because these boys do not produce as much testosterone as
other boys, they have a less muscular body, less facial and body hair,
and broader hips. As teens, XXY males may develop breast tissue and
also have weaker bones, and a lower energy level than other males.
By adulthood, XXY males look similar to males without the condition,
although they are often taller. In adults, possible characteristics vary
widely and include little to no sign of affectedness, a lanky, youthful
build and facial appearance, or a rounded body type with some degree of
gynecomastia (increased breast tissue). Gynecomastia is present to some
extent in about a third of affected individuals, a slightly higher
percentage than in the XY population. About 10% of XXY males have
gynecomastia noticeable enough that they may choose to have cosmetic
surgery.

16
Affected males are often infertile, or may have reduced fertility.
Advanced reproductive assistance is sometimes possible.
The term hypogonadism in XXY symptoms is often misinterpreted to
mean "small testicles" when it means decreased testicular
hormone/endocrine function. Because of this (primary) hypogonadism,
individuals often have a low serum testosterone level, but high serum
follicle-stimulating hormone and luteinizing hormone levels. Despite
this misunderstanding of the term, however, XXY men may also have
microorchidism (i.e., small testicles).

17
 5) Patau Symdrome
Patau syndrome is a syndrome caused by a chromosomal abnormality, in
which some or all of the cells of the body contain extra genetic material
from chromosome 13. The extra genetic material disrupts normal
development, causing multiple and complex organ defects.
This can occur either because each cell contains a full extra copy of
chromosome 13 (a disorder known as trisomy 13 or trisomy D), or
because each cell contains an extra partial copy of the chromosome or
because of mosaic Patau syndrome. Full trisomy 13 is caused by
nondisjunction of chromosomes during meiosis (the mosaic form is
caused by nondisjunction during mitosis).
Like all nondisjunction conditions (such as Down syndrome and
Edwards syndrome), the risk of this syndrome in the offspring increases
with maternal age at pregnancy, with about 31 years being the average.
Patau syndrome affects somewhere between 1 in 10,000 and 1 in 21,700
live births.

Signs and symptoms

Of those fetuses that do survive to gestation and subsequent birth,
common abnormalities may include:

 Nervous system
 Intellectual disability and motor disorder

18
 Microcephaly
 Holoprosencephaly (failure of the forebrain to divide properly).
 Structural eye defects, including microphthalmia, Peters' anomaly,
cataract, iris or fundus (coloboma), retinal dysplasia or retinal
detachment, sensory nystagmus, cortical visual loss, and optic
nerve hypoplasia
 Meningomyelocele (a spinal defect)

 Musculoskeletal and cutaneous

 Polydactyly (extra digits)
 Cyclopia
 Proboscis
 Congenital trigger digits
 Low-set ears[3]
 Prominent heel
 Deformed feet known as rocker-bottom feet
 Omphalocele (abdominal defect)
 Abnormal palm pattern
 Overlapping of fingers over thumb
 Cutis aplasia (missing portion of the skin/hair)
 Cleft palate

 Urogenital
 Abnormal genitalia
 Kidney defects
 Other

19
 6) Williams Syndrome
Williams syndrome (WS) is a genetic disorder that affects many parts of
the body. Facial features frequently include a broad forehead, short nose
and full cheeks, an appearance that has been described as "elfin".Mild to
moderate intellectual disability with particular problems with visual
spatial tasks such as drawing and fewer problems with language are
typical. Those affected often have an outgoing personality and interact
readily with strangers.Problems with teeth, heart problems, especially
supravalvular aortic stenosis, and periods of high blood calcium are
common.
Williams syndrome is caused by a genetic abnormality, specifically a
deletion of about 27 genes from the long arm of one of the two
chromosome 7s. Typically this occurs as a random event during the
formation of the egg or sperm from which a person develops. In a small
number of cases, it is inherited from an affected parent in an autosomal
dominant manner. The different characteristic features have been linked
to the loss of specific genes. The diagnosis is typically suspected based
on symptoms and confirmed by genetic testing.
Treatment includes special education programs and various types of
therapy. Surgery may be done to correct heart problems. Dietary
changes or medications may be required for high blood calcium. The
syndrome was first described in 1961 by New Zealander John C. P.
Williams. Williams syndrome affects between 1 in 7,500 to 1 in 20,000
people at birth. Life expectancy is less than that of the general
population, mostly due to the increased rates of heart disease.

20
Signs and symptoms
People with Williams syndrome experience many cardiac problems,
commonly heart murmurs and the narrowing of major blood vessels as
well as supravalvular aortic stenosis. Other symptoms may include
gastrointestinal problems, such as severe or prolonged colic, abdominal
pain and diverticulitis, nocturnal enuresis (bed wetting) and urinary
difficulties, dental irregularities and defective tooth enamel, as well as
hormone problems, the most common being high blood calcium.
Hypothyroidism has been reported to occur in children, although there is
no proof of it occurring in adults; adults with WS have a higher risk of
developing type 2 diabetes, with some cases apparent as young as 21
years old.
People with Williams syndrome often have hyperacusia and
phonophobia which resembles noise-induced hearing loss, but this may
be due to a malfunctioning auditory nerve. However, people with WS
can also tend to demonstrate a love of music, and they appear
significantly more likely to possess absolute pitch. There also appears to
be a higher prevalence of left-handedness and left-eye dominance.

21
Treatments
In many cases, there is no treatment or cure for chromosomal
abnormalities. However, some interventions may include:
Genetic counseling. If testing indicates your child has a chromosomal
abnormality, you will meet with a genetic counselor who will explain
the features of the condition, the short- and long-term features, what
interventions may prove helpful and the risk of recurrence in additional
family members.
Occupational therapy. Your child may need help from an occupational
therapist to learn certain skills of daily living, such as getting dressed,
bathing, eating and school-related tasks like writing.
Physical therapy. A physical therapist can help your child learn to build
muscle strength, improve motor skills and accomplish more daily tasks.
Cardiovascular medicines. For some chromosomal conditions, a
cardiologist will prescribe medicines to prevent dilation (enlargement)
of your child’s aorta and other blood vessels.

22
Photo Gallery

23
24
25
26
27
28