CHROMOSOMAL DISORDERS

Presented by G. Susila

I yr. M.Sc., (N)SHNC

Guided by Dr.(Mrs) Nalini Gopalakrishnan

Ph.D., PrincipalSHNC

CHROMOSOMAL DISORDER

IntroductionDiseases due to dysfunction of

hereditary material, like chromosomes and genes, are the oldest, most widespread and probably the most common burden some of all human affilictions. Birth defects about 80 percent of which are thought to be due to genetic defects, are amongst the leading causes of infant mortality and fetal loss. Several studies have shown that genetic disease has a severe impact on the newborn.

Down Syndrome (Trisomy 21)Down syndrome is the most common

cause of mental retardation and malformation in a newborn. It occurs because of the presence of an extra 21st chromosomes.

It was first described in 1866 by Dr.John. L.H. Down, an English Physician.

IncidenceDown syndrome occurs about once in

every 800 births. It is estimated that 10,000 children are born with down syndrome each year in the India.

Causes increased maternal age

Parents with chromosomal disorders Hereditary Chromosomal mutation

Types of Down Syndrome Mosaic down syndrome Translocation of down syndrome

Mosaic Down Syndrome

The original egg and sperm cells are completely normal.

The problem occur sometime shortly after fertilization, during the phase where cells are dividing rapidly, one cell divides abnormally, creating a line cells with an extra chromosome 21.

This form of genetic disorder is called as mosaic.

Karyotyping

Translocations Down Syndrome

During cell division the number 21st chromosome some how breaks.

A piece of the 21st chromosome then becomes attached to another chromosome.

Each cell still has 46 chromosomes but the extra piece of chromosome 21.

ResultsDown syndrome

Clinical Manifestations

Mangolion Face Simian Crease

Thick Fissured Tongue

Flattened Nose and Face, Upward Slanting Eyes

Increased space

between 1st and 2nd

toe

Short Fifth Finger that

curves inward

Down Syndrome Newborn

Epicanthic Folds

Other Problems

congenital heart diseaseHearing problemsCeliac diseaseCataractsThyroid dysfunctions

Turner Syndrome

Turner syndrome is a genetic condition

in which a female does not have the

usual pair of two x

chromosomes. It was first described in

1938 by Dr.Hentry turner, an

endocrinologist.

DescriptionNormal Females Turner Syndrome Females

x x x

Incidence

Turner syndrome occurs in about 1 out of 2,000 live births.

Clinical Manifestations

Infants

swollen hands and feet wide and webbed neck

Wide and Wide and Webbed NeckWebbed Neck Swollen FeetSwollen Feet

Shortened Shortened meta carpalmeta carpal Small Finger Small Finger

NailsNails

Short StructureShort Structure

Shortened 4Shortened 4thth & & 55thth Meta Carpal Meta CarpalLoss of HairLoss of Hair

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