This document summarizes several chromosomal disorders including trisomies, deletions, and sex chromosome abnormalities. It describes the karyotypes, causes, and typical symptoms of several conditions including Down syndrome, Patau syndrome, Edwards syndrome, DiGeorge syndrome, Klinefelter syndrome, and Turner syndrome. Structural abnormalities of chromosomes can result in an abnormal number of chromosomes or deletions/insertions of genetic material, leading to developmental delays and physical abnormalities.

1. By; omer Aslankan
Chromosomal Disorders
Normal Karyotype
human somatic cells contain 46 chromosomes;
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these comprise 22 homologous pairs of autosomes and two sex chromosomes, XX in the female and XY in the
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male.
normal male (46,XY)
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normal Female (46,XX)
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Structural Abnormalities of Chromosomes
abnormal number of chromosomes
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Insertion
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Deletion
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Robertsonian translocation
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Mosaic
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autosomal chromosome disorders
1) Trisomy 13;
Pataus syndrome; is a person has an extra chromosome.
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Karyotaype; (47,XX,+13 or 47,XY,+13);
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Caused; ıt is having 3 copies of chromosome 13 in each cell, instead of 2
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symptoms; Severe mental retardation, cleft lip/palate, heart defects
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2) Trisomy 18;
Edwards syndrome; is a person has an extra chromosome.
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Karyotaype; (47,XX,+18 or 47,XY,+18)
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Caused; it is having 3 copies of chromosome 18 in each cell in the body, instead of 2
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symptoms; is Severe mental retardation, rocker-bottom feet, Small mouth & chin
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3) Trisomy 21;
Down syndrome is a person has an extra chromosome.
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Down syndrome is meiotic nondisjunction.
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Karyotaype; (47,XX,+21 or 47,XY,+21)
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symptoms; mental retardation, eye abnormalities, A short neck, Small ears, Small hands and feet.
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Caused; ıt is having 3 copies of chromosome 21 in each cell, instead of 2
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Clinical features; Flat facial profile, oblique Palpebral fissures, epicanthic folds
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4) DiGeorge (22q11.2 Deletion or Velocardiofacial) Syndrome;
is caused by a deletion of a small part of chromosome 22
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Causes; small eyes, small ears, mean IQ in low 70s, overt cleft palate,hyperthyroidism, heart disease
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sex chromosome disorders
1) Klinefelter Syndrome;
Klinefelter syndrome; is a sex chromosomal disorders
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Caused; it is have extra copy of the X chromosome (affects males only)
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Karyotaype; 47, XXY
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symptoms; small testicles, tall height, tall arms and legs
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2. 2) Turner Syndrome
Turner Syndrome; is a sex chromosomal disorders
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Caused; having only one X chromosome (affects females only)
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Karyotaype; 45, X
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symptoms; short height, heart defects, failure of ovaries to develop.
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