Structural chromosomal abnormalities result from chromosome breakage and rearrangement. Types include deletions, inversions, ring chromosomes, duplications, and translocations. Specific disorders discussed include Down syndrome caused by trisomy 21 from nondisjunction; Cri du chat syndrome from deletion of chromosome 5p; Turner syndrome from X chromosome monosomy; and Klinefelter syndrome from XXY in males due to nondisjunction. Cytogenetic features and characteristics of each condition are described.

1. Chromosoal Disorders
Saleh Al-Missned
331116716
Supervised by /D.Mostaf

2.  Define 'structural chromosomal abnormalities; define
and describe each of the following.
 Deletion
 Inversion
 Ring chromosome
 Duplication
 Translocation
 Robertsonian translocation
 Isochromosome
Illustrate the features of some cytogenetic
disorders:
Down syndrome.
Cri du chat.
Turner syndrome.
Klinefelter syndrome.

3. * Definition :
Change in chromosome usually result from a chromosomal breakage
followed by loss or rearrangement material .
Type :
1- Deletion
2- Inversion
3- Ring chromosome
4- Duplication
5- Translocation
6- Isochromosome

4. * Definition :
Loss of a segment of a chromosome .
It could be :
1-Interstitial: loss of a segment within a chromosome (two breaks )
2-Terminal:loss of a segment at the end of a chromosome (single break)
Example :
Cri du Chat Syndrome .

5. * Definition:
Rearrangement that involves two breaks within a single chromosome
* It could be :
1-pericentric: if the breaks are on opposite side of centromere.
2-Paracentric: if the break in only one arm of chromosome.

6. * Definition :
loss of segments from each end of the chromosome, the
arms unite to form a ring.

7. * Definition:
Part of chromosome or gene is doubled without increase in
the total number of chromosome.

8. * Definition :
one chromosome Segment is transferred to another
It’s two types:
a-Balanced reciprocal:
If there are single breaks in each of two chromosome
b-Robertsonian translocation:
It is a special type of translocation between two acrocentric
chromosome
The breaks occur close to the centromeres of each chromosome. Then
,lead to very long chromosomeand extremely small one.(usually the
small product is lost)

10. Definition :
It is result if the centromere has divided transversely rather than
longitudinally.
* Result
one chromosome has two upper arms
the other has two lower arms.

11. * Epidemiology:
It occurs in 1 in 1550 live
births in women younger
than 20 years in contrast
to 1 in 25 live births in
women older than 45
years.

12. * It is autosomal abnormality.
* Approximately 95% of cases of
Down syndrome are due to
maternal meiotic
nondisjunction.
* About 4% of all the patient with
trisomy 21 the extra chromosome
material is present not as extra
chromosome but as translocation
of the long arm of chromosome 21
to chromosome 22 or 14.

13. Normal division Non disjunction

14. Trisomy 21

15. Clinical Features
*Increase
susceptibilityto
infectionand
Alzheimer
disease.
*Thyroid
disorder,eyeand
hearing disorder.
*Intestinal
stenosis

16. * Rare genetic disorder.
* 90% of the cases is not
hereditary.
* It is autosomal deletion
caused by a partial deletion of
chromosome 5p .

17. 1. Cat like cry
2.Facial abnormality
3.Behavioral problems
4.Widely spaced eyes (ocular
hypertelorism)
5.Short fingers

18. •It is chromosomal abnormality in sex
chromosome result from partial or complete
monosomy of the short arm of x chromosome, so
their chromosomes count is 45.
•What is monosomy
Monosomy : It is the condition that absence or decrease of one chromosome
 -In autosome : incompatible with life.
 -In sex chromosome: compatible with life e.g. Turner syndrome
•It occurs only in females.
* Characterized by female hypogonadism.
* Cytogenetic features:
1.Isochromosome
2.Non disjunction
3.Mosaicism

20. A male hypogonadism that develop when there
are at least two x chromosome and one or more Y
chromosome. Most patients are 47,XXY
* Cytogenetic features:
1.Chromosomal non disjunction during meiosis.
2. Mosaicism
What is Mosaicism
 Mosaicism : It is a mitotic errors in early development give
rise to 2 or more population of cell in the same individual.
Result from Mitotic errors during cleavage .
Mosaicism effecting often the sex chromosome

23. Structural abnormalities
Change in chromosome usually result from achromosomal breakage followed by loss or
rearrangement material
Deletion Loss of a segment of a chromosome
Inversion Rearrangement that involves two breaks within a single chromosome
Ring chromosome loss of segments from each end of the chromosome, the arms unite to form a
ring.
Duplication
Part of chromosome or gene is doubled without increase in the total number of chromosome.
Translocation one chromosome Segment is transferred to another
Isochromosome It is result if the centromere has divided transversely rather than longitudinally
the features of some cytogenetic
Down Syndrome (47,XY) -Non-disjunction -Translocation
5(deletion of chromosome5.p) short arm cases is not hereditaryCri du chat syndrome
Turner syndrome
Mosaicism-Non disjunctio-(45,x) It occurs only in females Isochromosome
Mosaicism-Klinefelter syndrome (47,XXY) 1.Chromosomal non disjunction during meiosis

25.  ROBBINS (Basic Pathology) 8th edition
 Pathologic Basis Of Disease.
 The pictures form the U.S national Library of medicine