1. Chromosomal disorders

2. Body, cells, chromosomes
23 pairs of chromosomes
+ mitochondrial DNAs
Human body: 10 trillion cells

3. karyogram
Cytogenetics
- karyotype
Giemsa staining

4. Homologous chromosomes
Daughter chromosomes
Sister chromatids

5. Meiózis I
Meiózis II
n: number of chromosomes
c: number of chromatids

6. Nondisjunction in meiosis
MEIOSIS - I
MEIOSIS - II
FERILIZATION
ZYGOTE
Disjunction = separation

7. Chromosomal aberrations
Structural disorders
translocations
Insertions/
deletions
duplications
inversions
Ring chromosomes
Numerical disorders
Aneuploidy
Hyperploidy
Trisomy
(2n+1)
Tetrasomy
(2n+2)
Hypoploidy
Monosomy
(2n-1)
Nullisomy
(2n-2)
Euploidy
Monoloidy
(n)
Diploidy
(2n)
Polyploidy
(3n,4n,etc.)
Chromosomal aberrations
Aberration in a cell vs. in every cell of an organism

8. Numerical aberrations
Autosomes
Patau-syndrome
(13-trisomy)
Edwards-syndromes
(18-trisomy)
Down-syndrome
(21-trisomy
Sex chromosomss
Turner-syndrome
(X0)
Triple X syndrome
(XXX)
Klinefelter syndrome
(XXY)
Double Y syndrome
(XYY)

9. Patau-syndrome (trisomy 13)
A chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. Affected individuals with this disorder often have brain or spinal cord abnormalities, heart defects, poorly developed eyes, extra fingers or toes, an opening in the lip frequently associated with an opening in the roof of the mouth, and weak muscle tone (hypotonia).
Many infants with trisomy 13 die within their first days or weeks of life. Only 5 to 10 percent of children with this condition live past their first year.
occurrence: 1/16,000

10. Edwards syndrome (trisomy 18)
This chromosomal condition may be associated with heart defects and abnormalities of other organs. Other features include a small, abnormally shaped head; a small jaw and mouth; and clenched fists with overlapping fingers. Most affected individuals die before birth or within their first month.
5 to 10 % of children with this condition live past their first year, and these children often have severe intellectual disability.
Occurrence: 1/5,000

11. Down-syndrome (trisomy 21)
This syndrome is associated with a characteristic facial appearance, and hypotonia in infancy. Affected individuals experience cognitive delays, but the intellectual disability is usually mild to moderate. About half of all affected children are born with a heart defect. Individuals with Down syndrome also have an increased risk of hearing and vision problems.
occurrence: 1/800

12. Turner syndrome (X0)
The most common feature of this syndrome is short stature. Many affected girls do not undergo puberty unless they receive hormone therapy, and most are infertile. Turner syndrome occurs in about 1 in 2,500 newborn girls worldwide.

13. Triple X syndrome (XXX)
Most females with triple X syndrome are able to conceive children. This condition is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills, hypotonia, and behavioral and emotional difficulties are also possible.
This syndrome occurs in about 1 in 1,000 newborn girls.
Four or even more X chromosome can also occur.

14. Klinefelter syndrome (XXY)
This disease affects male physical and cognitive development. Affected individuals typically have small testes that do not produce as much testosterone as usual. A shortage of testosterone can lead to delayed or incomplete puberty, breast enlargement, reduced facial and body hair, and infertility. have an increased risk of developing breast cancer and a chronic inflammatory disease. Children with Klinefelter syndrome may have learning disabilities and delayed speech and language development.
Klinefelter syndrome affects 1 in 500 to 1,000 newborn males.

15. Double Y syndrome(XYY)
Males with this condition may be taller than average, this chromosomal change typically causes no unusual physical features. Most males with 47,XYY syndrome have normal sexual development and are able to father children. This syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills, hypotonia, and behavioral and emotional difficulties.
This syndrome occurs in about 1 in 1,000 male birth.

16. Structural abnormalities
Two chromosome mutations
Single chromosome mutations
insertional translocation
deletion
duplication
inversion
ring chromosome
isochromosome
reciprocal translocation

17. Chromosomal deletion syndromes
Wolf–Hirschhorn syndrome (4p16.3)
Jacobsen syndrome (11q24.1)
Chri du chat szindróma (5p15.1)

18. Chromosomal duplication syndromes
Charcot–Marie–Tooth disease
Mutations on various chromosomes can cause the disease
1q21.1 duplication syndrome

19. Nondisjunction in mitosis
It causes mosaicism

20. Chromosomal mosaicism

21. Genetic mosaicism in the brain
Not only chromosomal mosaicism!