Genetic Disorders in Humans Presentation

8/7/2019 Genetic Disorders in Humans Presentation

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Achondroplasiay It is an autosomal dominant

genetic disorder better known as

dwarfism. Height varies from 4

feet to 4 feet 4 inches with

disproportionately short limbs.

y However, there is no intellectual

disability. In this disorder, the

cartilage, specially in the long

bones, fail to convert into bones.y Caused by a defect of a gene

located on chromosome 4.



Albinismy Albinism is a congenital

disorder in which there islittle or completely noproduction of melanin in

hair, skin and iris of theeyes.

y They have light coloredskin, hair and eyes.

y

Caused by an inheritanceof recessive alleles fromparents.



Angelman syndromey This disorder is marked by intellectual

and developmental delays, severe

speech impairment and problems in

movement and balance,

recurrent seizures and small heads.

y Children withAngelman syndrome

typically have a happy demeanor. They

are hyperactive with short attention

span and show jerky hand movements.y The disorder is caused due to deletion

of the maternally inherited

chromosome 15.



Cri-du-Chat Syndromey Cri du Chat syndrome is caused due

to deletion of short (p) arm of chromosome 5.

y The syndrome gets the name from

the characteristic high pitched cry of an infant that resembles the cry of acat. Other symptoms are intellectualdisabilities, delayed development,microcephaly (small head), low

birth weight, typical facial featuresand weak muscle tones duringinfancy. No specific treatment isavailable for this disorder.



Down Syndromey Also called Trisomy 21 it is a genetic

disorder in human that is the result of extra copy of chromosome 21.

y This extra genetic material causes

delays in mental as well as physicaldevelopment of a child.

y Symptoms include a narrow chin, aprominently round face, protrudingtongue, short limbs, the Simian crease

and poor muscle tone.y The incidence of this disorder

increases with maternal age.Karyotyping test of a child confirmsthis syndrome.



Fragile X Syndromey Fragile X syndrome is the most

common cause of inheritedform of mental retardation.

y It is caused by a partial additionto the q-region of the Xchromosome.

y The result is intellectualdisabilities, high levels of anxiety and hyperactivity likefidgeting, autistic behavior like

hand flapping, avoiding eyecontact, shyness, mentalretardation and attention deficitdisorder and other symptoms.



Fragile X Syndrome



Huntington's Diseasey Autosomal dominant genetic disorder in

the huntingtin gene, that produces afaulty protein instead of the normal"huntingtin" protein.

y The faulty protein causes damage to

specific areas of the brain, causinginvoluntary movements oruncoordinated jerky movements.As thedisease progresses, decline on mentalabilities (marked with dementia),behavioral and psychiatric problems

become prominent.y Although physical symptoms of

Huntington's disease may manifest at anyage, it most commonly occurs inindividuals between 35 to 45 years old.There is no cure.



Klinefelter Syndromey It is the most common sex linked

genetic disorder. In which males

have an extra X chromosome.

Hence ,this disorder is also known

as 47, XXY or XXY syndrome.

y The most common symptom is

infertility, but may also have

impaired physical, language and

social developments.A

s theseindividuals produce less testosterone

than other males, such teenagers

may be less muscular and have less

facial hair than their peers.



Langer-Giedion Syndromey A genetic disorder in human that is

caused due to deletion or mutation of at least two genes on chromosome 8.

y This is not an inherited disorder. It iscaused due to random events duringformation of reproductive cells(sperms and eggs) in individuals.

y Causes bone abnormalities and typicalfacial features, multiple non-cancerous tumors in their bones that

cause pain, restrict joint movementand exerts pressure on nerves, bloodvessels, spinal cord and the tissuessurrounding the tumors. Someintellectual disability may beassociated with this disorder.



Triple X Syndromey Trisomy which results in an extra copy of the

X chromosome in females.

y It is caused due to non-disjunction during celldivision, that results in an extra copy of chromosome in reproductive cells. In some

cases, the extra copy of X chromosome maybe caused during cell division in earlyembryonic development.

y Most diagnosed have normal sexualdevelopment and are able to conceivechildren, but some have learning disabilities

and delayed development of speech andlanguage skills, weak muscle tone, andbehavioral and emotional difficulties.However, these characteristics vary widelyamong affected girls and women.



Patau Syndromey Also known trisomy 13, Patau syndrome is

caused due to non-disjunction of chromosome 13 during meiosis, due towhich, an affected individual inherits anextra copy of the chromosome.

y

The extra copy of chromosome results inkidney and heart defects, neurologicalproblems, facial defects, polydactyly(having extra fingers) and deformed feet.

y While certain infants may be able tosurvive only for a couple of days,

depending upon the severity of theconditions, those who survive with mildersymptoms undergo treatment, focusingthe particular disability that eachindividual suffers from.



Turner Syndromey Turner syndrome refers to a condition

in which a woman lacks either onewhole or a part of an X chromosome.

y The most characteristic feature of Turner syndrome is small stature that

becomes evident when one is around 5years old.

y Symptoms include loss of ovarianfunctions, absence of menstrual cycle,broad chest, low hairline and webbedneck. Since, this is a chromosomal

abnormality, there is no cure.However, estrogen replacementtherapy and doses of growth hormonesare successful in minimizing thesymptoms.



XXXX Syndromey Tetrasomy X, Quadruple X , the XXXX syndrome is a

chromosomal aneuploidy, that is, it arises due to a defect inmeiosis. This happens when homologous chromosomes failto separate during meiosis when the reproductive cells

(sperms and eggs) are formed.

y The symptoms of this disorder range from mild to severe.Physically, these women have epicanthic folds, flat nosebridge, cleft or highly arched palate, teeth and enamel

defects. Delay in development of speech, language andmotor skills is also found.Also may have defects in vision,hearing, kidneys, circulatory system and nervous system.50% of women with XXXX do not ever develop a menstrualperiod.



YY Syndromey As the name suggests, YY

syndrome is the result of chromosomal aneuploidy due towhich a male has an extra Y

chromosome. Other than beingnoticeably taller than their peers,males suffering from thiscondition do not have any otherunusual physical features.However, these individuals are ata risk of suffering from learningdisabilities and delayeddevelopment of speech andlanguage skills.

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Genetic Disorders in Humans Presentation