Chromosomal-aberrations.Chromosomal-aberrationspptx

g10 lesson biology

1. Chromosomal Aberrations or abnormalities Humans have 23 pairs of chromosomes The first 22 pairs are called autosomes or body chromosomes and the last pair or 23 rd pair i s called sex chromosomes

2. Chromosomal Aberrations or abnormalities Chromosomal aberrations are structural changes in chromosomes that can lead to genetic disorders or diseases. These aberrations can occur in various forms, such as: deletions, duplications, inversions, translocations, or the presence of an extra chromosome (trisomy) or a missing chromosome (monosomy).

3. Changes to: the structure of chromosomes deletions, duplications, inversions, translocations, or number of chromosomes (non-disjunction of chromosomes) trisomy monosomy

4. Chromosomal Aberrations or abnormalities In general, each parent contributes one set of chromosomes to their offspring, which collectively make up 23 pairs of chromosomes. A change to any of the chromosomes, in number or structure , creates a  chromosomal aberration   and may cause medical disorders.

5. What is a duplication mutation? In the case of a duplication mutation, a piece of DNA is (abnormally) copied. This might happen once or several times, and can therefore impact the functionality of the encoded protein.

6. Deletion in chromosome no. 5

7. Mixed up pieces These are called translocations , and involve pieces of non-homologous chromosomes swapping locations. They are the most common chromosomal abnormalities in humans—1 in 500 people have a translocation. 

8. Some Disorders due to mutations / chromosomal aberrations 11

9. 43 XX 43 XX 45 XY 45XY

10. This is what the karyotype looks like: Down syndrome, trisomy 21 The incidence of trisomy 21 rises sharply with increasing maternal age.

11. Chromosomal disorders: Down syndrome is caused by non-disjunction of the 21st chromosome during meiosis. As a result, the child has three 21st chromosomes instead of the normal two. Down Syndrome is a genetic disorder but it is not caused by having a harmful gene. These are children with Down's Syndrome:  

12. A child with Cri-Du-Chat Syndrome… Hi! I’m Gemma

13. Missing Pieces or Deletions Cri-du-chat Syndrome: "Cry of the Cat" Syndrome;  Terminal deletion: a part of the short arm near the end of chromosome 5 is deleted.  The name of this deletion refers to cry of children who have this defect; they suffer from mental retardation, a shortened life span, and a distinctive facial appearance.  It occurs one in 50,000 births.

14. Edwards Syndrome Trisomy 18 Infant with Edwards syndrome. Note microphthalmia, micrognathia/retrognathia, microstomia, low set/malformed ears, short sternum, and abnormal clenched fingers. Roland

15. The karyotype here demonstrates trisomy 13 (47, XX, +13) also known as Patau's syndrome . It occurs in only 1 in 6000 live births. It is rare for babies to survive for very long if liveborn because of the multitude of anomalies that are usually present.

16. Chromosomal Aberrations in Sex Chromosomes

17. Turner syndrome, 45, XO a health condition that affects females and involves the partial or complete absence of an X chromosome .  1 in 500 female births but this is only the tip of the iceberg, 99% of Turner syndrome embryos are spontaneously aborted. Individuals are very short and usually infertile. Characteristic body shape changes include a broad chest with widely spaced nipples and may include a webbed neck. IQ and lifespan are unaffected .

18. XO – Turner’s syndrome About one woman in 1000 has an extra X chromosome. It seems to do little harm; individuals are fertile They do have a reduction in IQ

19. XXX females (Meta-female) About one woman in 1000 has an extra X chromosome. It seems to do little harm; individuals are fertile They do have a reduction in IQ

20. Above is a karyotype showing someone with Klinefelter's Syndrome.  Please note the extra X chromosome Klinefelter's Syndrome:   44 + XXY XX Y

21. Klinefelter’s Syndrome: 47, XXY.  The individual has two or more X chromosomes and a Y chromosome (XXY or XXXY) develops as a male and has subtle physical defects.  Y Chromosome defines a male's outward appearance, no matter how many X chromosomes one may have. 

22. 47, XYY (Jacob’s Syndrome) 1 in 1000 male births. Males are tall but normally proportioned. 10 - 15 points reduction in IQ compared to sibs. Strangely, although fertile, they do not seem to transmit this condition or Klinefelter's syndrome.