Chromosome

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250,000 in US has Down syndrome.

The cost and maintaining Down syndrome case in US is estimated at $ 1 billion per year.

Slide 88

Patients having Down syndrome will Short in stature (four feet tall) and had an epicanthal fold, broad short skulls, wild nostrils, large tongue, stubby hands

Some babies may have short necks, small hands, and short fingers.

They are characterized as low in mentality.

Down syndrome results if the extra chromosome is number 21.

Slide 89

Amniocentesis for Detecting Aneuploidy

Chromosomal abnormalities are sufficiently well understood to permit genetic counseling.

A fetus may be checked in early stages of development by karyotyping the cultured cells obtained by a process called amniocentesis.

A sample of fluid will taken from mother and fetal cells are cultured and after a period of two to three weeks, chromosomes in dividing cells can be stained and observed.

If three No.21 chromosomes are present, Down syndrome confirmed.

Slide 90

The risk for mothers less than 25 years of age to have the trisomy is about 1 in 1500 births.

At 40 years of age, 1 in 100 births

At 45 years 1 in 40 births.

Slide 91

Other Syndromes

Chromosome Nomenclature: 47, +13

Chromosome formula: 2n+1

Clinical Syndrome: Trisomy-13

Estimated Frequency Birth: 1/20,000

Main Phenotypic Characteristics:

Mental deficiency and deafness, minor muscle seizures, cleft lip, cardiac anomalies

Slide 92

Other Syndromes

Chromosome Nomenclature: 47, +18

Chromosome formula: 2n+1

Clinical Syndrome: Trisomy-18

Estimated Frequency Birth: 1/8,000

Main Phenotypic Characteristics:

Multiple congenital malformation of many organs, malformed ears, small mouth and nose with general elfin appearance.

90% die in the first 6 months.

Slide 93

Other Syndromes

Chromosome Nomenclature: 45, X

Chromosome formula: 2n - 1

Clinical Syndrome: Turner

Estimated Frequency Birth: 1/2,500 female

Main Phenotypic Characteristics:

Female with retarded sexual development, usually sterile, short stature, webbing of skin in neck region, cardiovascular abnormalities, hearing impairment.

Slide 94

Other Syndromes

Chromosome Nomenclature: 47, XXY, 48, XXXY, 48,XXYY, 49, XXXXY, 50, XXXXXY

Chromosome formula: 2n+1; 2n+2; 2n+2; 2n+3; 2n+4