HUMAN CHROMOSOME

AND CHROMOSOME

BEHAVIOR

SUBMITTED BY:ALABADO, SHEENA ANN C.

LUISTRO, JANELLE

What is a chromosome?

A chromosome is…

A very long DNA molecule and associated proteins that carries portions of the hereditary information of an organism.

They are composed of DNA and proteins that are located within the nucleus of our cells. Chromosomes determine everything from hair color and eye color to sex.

Chromosomes are described with the following categories: Metacentric

centromere is median or near medianchromosome has two well defined

arms with a length ratio varying from 1:1 to 2.5:1

SubmetacentricA chromosome whose centromere lies

between its middle and its end but closer to the middle.

Chromosomes are described with the following categories: Acrocentric

centromere is close to one end of the chromosome

one arm is substantially smaller than the other and the arm ratio ranges from 3:1 to 10:1

Telocentriccentromere is a strictly terminal entity and the

chromosome is one armed

Chromosomes are described with the following categories:

Chromosomes are always arranged with the short arm on top: Short arm is labeled

P (French for petit) Long arm is labeled

Q

Human chromosomes are divided into 7 groups & sex chromosomes A 1-3 Large metacentric 1,2 or

submetacentric B 4,5 Large submetacentric, all similar C 6-12, X Medium sized, submetacentric -

difficult D 13-15 medium-sized acrocentric plus

satellites E 16-18 short metacentric 16 or

submetacentric 17,18 F 19-20 Short metacentrics G 21,22,Y Short acrocentrics with satellites. Y

no satellites.

KARYOTYPE

Karyotype An individual's

collection of chromosomes.

It refers to the complement of chromosomes either at the species level, or of individuals.

Is used to look for abnormal numbers or structures of chromosomes.

Karyotyping Also known as Karyotype Test A laboratory technique that produces an

image of an individual's chromosomes. Is a test to identify and evaluate the

size, shape, and number of chromosomes in a sample of body cells.

Extra, missing, or abnormal positions of chromosome pieces can cause problems with a person's growth, development, and body functions.

Why Karyotyping is done: Determine whether the chromosomes

of an adult have an abnormality that can be passed on to a child.

Determine whether a chromosome defect is preventing a woman from becoming pregnant or causing miscarriages.

Determine whether a chromosome defect is present in a fetus.

Why Karyotyping is done: Determine whether chromosomal problems

may have caused a fetus to be stillborn.

Determine the cause of a baby's birth defects or disability.

Help determine the appropriate treatment for some types of cancer.

Identify the sex of a person by determining the presence of the Y chromosome. This may be done when a newborn's sex is not clear.

CHROMOSOMAL ABBERATIONS

Chromosomal Aberrations Sex chromosome abnormalities occur as a

result of chromosome mutations brought on by mutagens (like radiation) or problems that occur during meiosis.

One type of mutation is caused by chromosome breakage. The broken chromosome fragment may be deleted, duplicated, inverted, or translocated to a non-homologous chromosome.

Another type of mutation occurs during meiosis and causes cells to have either too many or not enough chromosomes.

Klinefelter Syndrome (XXY) Klinefelter syndrome, also known as the XXY

condition, is a term used to describe males who have an extra X chromosome in most of their cells. Instead of having the usual XY chromosome pattern that most males have, these men have an XXY pattern.

Klinefelter syndrome is named after Dr. Henry Klinefelter, who first described a group of symptoms found in some men with the extra X chromosome.

Scientists believe the XXY condition is one of

the most common chromosome abnormalities in humans. About one of every 500 males has an extra X chromosome, but many don’t have any symptoms.

Klinefelter Syndrome (XXY) Common Physical

Characteristics:small testicles and penisBreast enlargementsterilityinfertile

Klinefelter Syndrome (XXY)

Metafemale (XXX) A metafemale is a woman who has an extra

X chromosome. It is a condition that is commonly referred to as Triple X Syndrome and it is thought to affect around 1 in every 1000 women.

Triple X Syndrome results during division of a parent's reproductive cells.

In most cases there will be no unusual physical features or medical problems resulting from Triple X Syndrome. This is because in all female cells there is only one active X chromosome at any one time.

Metafemale (XXX)

Common Physical Characteristics:Generally normal due to Barr BodiesTall statureBehavioral problemsClumsiness and poor co-ordinationWide-set eyesReduced muscle toneOvarian failure

Metafemale (XXX)

Turner Syndrome (XO) Turner syndrome is a chromosomal

condition that alters development in females.

This condition occurs in about 1 in 2,500 female births worldwide, but is much more common among pregnancies that do not survive to term (miscarriages and stillbirths).

Turner syndrome is a chromosomal condition related to the X chromosome

Researchers have not yet determined which genes on the X chromosome are responsible for most signs and symptoms of Turner syndrome.

Turner Syndrome (XO)

Common Physical Characteristics:extra skin on the neck (webbed neck)puffiness or swelling (lymphedema) of

the hands and feetskeletal abnormalitiesheart defectskidney problems

Turner Syndrome (XO)

Jacobs Syndrome (XYY)

Jacob's syndrome is a rare chromosomal disorder that affects males. It is caused by the presence of an extra Y chromosome. Males normally have one X and one Y chromosome. However, individuals with Jacob's syndrome have one X and two Y chromosome.

Males with Jacob's syndrome, also called XYY males.

Jacob's syndrome occurs when a male inherits two Y chromosomes from his father instead of one. He is an XYY male. Most males are XY.

The exact cause of the XYY aberration is unknown.

Jacobs Syndrome (XYY) Common Physical

Characteristics:With uncontrolled temper and

antisocialSevere acne problemsTall and thinHigh testosterone levels

Jacobs Syndrome (XYY)

AUTOSOMAL ABERRATIONS

Autosomal Aberrations

Syndrome or disorder of interest is pertaining to a chromosome that is NOT a sex chromosome, either X or Y but of body chromosomes.

Down Syndrome (Trisomy 21) Down syndrome (also called Trisomy

21) is a genetic disorder that occurs in approximately 1 of 800 live births.

Down syndrome is named after Doctor Langdon Down, who in 1866 first described the syndrome as a disorder.

It is the leading cause of cognitive impairment.

Down Syndrome (Trisomy 21) Common Physical Characteristics:

Oblique eye featuresmild to moderate learning disabilitiesDevelopmental delaysCharacteristic facial features, Low muscle tone in early infancy. Epicanthal foldSimian crease

Down Syndrome (Trisomy 21)

Edward Syndrome (Trisomy 18) The Edward's syndrome, which got its

name after the famous doctor, Dr. John Edward.

A genetic chromosomal disorder caused by an error in cell division resulting on additional third chromosome 18.

Edward's syndrome, a result of one of the genetic disorders and most common after Down syndrome, occurs in approximately one among 3000 to 6000 births.

Edward Syndrome (Trisomy 18) Common Physical

Characteristics:Upturned noseGrowth DeficiencyAbnormal skull shape and facial

featuresClenched handsRocker bottom feetCardiac and renal abnormalities

Edward Syndrome (Trisomy 18)

Patau Syndrome (Trisomy 13) Patau syndrome, also referred to as,

'Trisomy 13. A form of genetic disorder in which all or

a portion of the person's chromosome thirteen appears three times instead of twice in the cells of their body.

The extra material interferes with the person's regular process of development, which leads to severe intellectual disability and physical abnormalities in a number of parts of their body.

Patau Syndrome (Trisomy 13) Common Physical Characteristics:

Polydactyl and cleft palateLow-set earsScalp defectsClenched handsSmall lower jawMental retardationSingle palmar creaseUndescended testicleSkeletal abnormalitiesClose-set eyes - eyes may actually fuse

together

Patau Syndrome (Trisomy 13)

Angelman Syndrome A neuro-genetic disorder that it is usually

caused by deletion or inactivation of genes on the maternally inherited chromosome 15 while the paternal copy, which may be of normal sequence, is imprinted and therefore silenced.

AS is named after a British pediatrician, Dr. Harry Angelman, who first described the syndrome in 1965.

People with AS are sometimes known as "angels", both because of the syndrome's name and because of their youthful, happy appearance.

Angelman Syndrome

Common Physical Characteristics:Intellectual and developmental delaySleep disturbanceSeizuresJerky movements (especially hand-

flapping)Frequent laughter or smilingUsually a happy demeanor.

Angelman Syndrome

Note: The deletion in Chromosome 15 is so small and is almost not visible

Prader–Willi syndrome

Is a rare genetic disorder in which seven genes (or some subset thereof) on chromosome 15 (q 11–13) are deleted or unexpressed (chromosome 15q partial deletion) on the paternal chromosome.

It was first described in 1956 by Andrea Prader (1919–2001), Heinrich Willi (1900–1971), Alexis Labhart (1916), Andrew Ziegler, and Guido Fanconi of Switzerland.

Prader–Willi syndrome Common Physical

Characteristics:Low muscle toneShort statureIncomplete sexual developmentCognitive disabilitiesProblem behaviorsChronic feeling of hunger that can

lead to excessive eating and life-threatening obesity

Prader–Willi syndrome

STRUCTURAL ABERRATIONS

-The chromosome's structure is altered

Structural Aberrations

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.

Structural Aberrations Translocations

When a portion of one chromosome is transferred to another chromosome. There are two main types of translocations. In a reciprocal translocation, segments from two different chromosomes have been exchanged. In a 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.

InversionsA portion of the chromosome has broken off,

turned upside down and reattached, therefore the genetic material is inverted.

Structural Aberrations Insertions

A portion of one chromosome has been removed from its normal place and inserted into another chromosome.

RingsA portion of a chromosome has broken off and

formed a circle or ring. This can happen with or without loss of genetic material.

IsochromosomeFormed by the mirror image copy of a

chromosome segment including the centromere.

Wolf-Hirschhorn Syndrome

A syndrome is due to a specific chromosomal deletion which is the cause of typical facial features and developmental delays.

The anomalies are due to the lack of chromosomal material from the top of one of the number 4 chromosomes.

This results in missing genes which account for the anomalies. The degree of deletions and scope of symptoms vary widely and reflect the amount of genetic material that is missing.

Wolf-Hirschhorn Syndrome Common Physical

Characteristics:Short philtrumSmall head size (microcephaly)"Greek helmet like" nose shapeWide spaced eyes (hypertelorism)Mental retardation

Wolf-Hirschhorn Syndrome

Cri-du-chat Syndrome Also known as chromosome 5p deletion

syndrome, 5p minus syndrome or Lejeune’s syndrome

A rare genetic disorder due to a missing part of chromosome 5. Its name is a French term (cat-cry or call of the cat) referring to the characteristic cat-like cry of affected children.

It was first described by Jérôme Lejeune in 1963. The condition affects an estimated 1 in 50,000 live births, strikes all ethnicities, and is more common in females by a 4:3 ratio.

Cri-du-chat Syndrome Common Physical Characteristics:

Excessive droolingFeeding problems because of difficulty

swallowing and sucking.Low birth weight and poor growthSevere cognitive, speech, and motor delaysBehavioral problems such as hyperactivity,

aggression, tantrums, and repetitive movements.

Unusual facial features which may change over time

Cri-du-chat Syndrome

Cat eye Syndrome A rare condition caused by the short arm (p) and

a small section of the long arm (q) of human Chromosome 22 being present three (trisomic) or four times (tetrasomic) instead of the usual two times.

The term "Cat Eye" syndrome was coined because of the particular appearance of the vertical colobomas in the eyes of some patients.

However, over half of the CES patients in the literature do not present with this trait. There is no significant reduction in life expectancy in patients who are not afflicted with one of CES' life threatening abnormalities.

Cat eye Syndrome Common Physical Characteristics:

Iris colobomaAnal atresia (abnormal obstruction of the anus)Unilateral or bilateral iris coloboma (absence of tissue from

the colored part of the eyes)Palpebral fissures (downward slanting openings between the

upper and lower eyelids)Preauricular pits/tags (small depressions/growths of skin on

the outer ears)Cardiac defects (such as TAPVR)Kidney problems (missing, extra, or underdeveloped kidneys)Short statureScoliosis/Skeletal problems

Cat eye Syndrome

Velo-Cardio-Facial Syndrome

Velocardiofacial syndrome is a genetic disorder that is present from birth and can be characterized by a variety (over thirty) different signs and symptoms.

Although the gene or genes that cause velocardiofacial syndrome have not been identified, most of the children who have been diagnosed with this syndrome are missing a small part of chromosome 22.

Velo-Cardio-Facial Syndrome Common Physical Characteristics:

cleft palate (opening in the roof of the mouth)

heart defects, certain facial featuresminor learning problems speech and feeding problems

Velo-Cardio-Facial Syndrome

Charcot-Marie-Tooth Disease

Also known also as Morbus Charcot-Marie-Tooth, Charcot-Marie-Tooth neuropathy, hereditary motor and sensory neuropathy (HMSN), hereditary sensorimotor neuropathy (HSMN), or peroneal muscular atrophy.

An inherited disorder of nerves (neuropathy) that takes different forms.

It is caused by duplication of the gene encoding peripheral myelin protein 22 (PMP22) on chromosome 17.

Charcot-Marie-Tooth Disease Common Physical Characteristics:

Foot drop which is the dropping of the forefoot due to weakness, damage to the peroneal nerve or paralysis of the muscles in the anterior portion of the lower leg.

ScoliosisMalformed hip sockets Gastrointestinal problems can be part of

CMT, as can chewing, swallowing, and speaking (as vocal cords atrophy).

Charcot-Marie-Tooth Disease