Chromosomal aberrations are disruptions in the normal chromosomal content of a cell. In other words, they are changes in the number and or arrangement of genes in the chromosomes.

1. PRESENTED BY:
Mrs. Aakanksha Bajpai
Nursing Lecturer
Dept of Pediatrics
RAMA UNIVERSITY

2. INTRODUCTION
 The word ‘Chromosome’ is derived from Greek
word “chroma”-color and “soma”- body .
 Normally in males we have 44+xy and in female we
have 44+xx chromosomes
 A female ova consists of 23 chromosomes and sperm
consists of 23 chromosomes so after fertilization a
zygote comprises of 46 chromosomes(23 pairs)

3. STRUCTURE OF CHROMOSOME

4. DEFINITION
Chromosomal aberrations are disruptions in the
normal chromosomal content of a cell.
In other words, they are changes in the number and
or arrangement of genes in the chromosomes.

5. ETIOLOGY
 Meiosis-if there is an error in cell division,
the egg or sperm can end up with too many or
not enough chromosomes.
 Mitosis- if the chromosome do not split into
equal halves, the new cells can have an extra
chromosome or have a missing chromosome.

6. ETIOLOGY
 Maternal age- eggs are also aging and may have the
incorrect number of chromosomes at the time of fertlization.
 Consanguinity- it describes a relationship between two
people who share a common ancestor or a shared blood
relationship .
 Radiations- it is teratogenic
 Environment- it may include medications, foods, etc.

7. TYPES OF CHROMOSOMALABERRATIONS
CHROMOSOMAL ABERRATIONS
NUMERICAL STRUCTURAL
•MONOSOMY
•TRISOMY
•TETRASOMY
•TRIPLOIDY
•TETRAPLOIDY
•DELETION
•TRANSLOCATION
•INSERTION
•INVERSION
•ISOCHROMOSOME
•RING CHROMOSOME
•DUPLICATION

9. MONOSOMY
 In this one chromosome is missing.
 When a chromosome does not separate properly
during meiosis I or II it is called as meiotic
nondisjunction.
 It is incompatible with survival because of loss of
too much genetic information.

11. MONOSOMY

12. TRISOMY
 3 instances of a particular chromosome are
present instead of normal 2 chromosomes.
 Occurs if the chromosomes fail to separate
properly during cell division.

14. TRISOMY

15. TETRASOMY
 It Is a deviation of an abnormal number of
chromosomes in which an additional
chromosomal pair is added to particular
chromosome(2n+2).
 A cell contain 48 chromosomes here.

16. TETRASOMY

17. TRIPLOIDY
 There is a complete set of extra chromosomes.
 It can be due to:
a. Egg is fertilized by a sperm with a double set of
chromosomes.
b. The egg is fertilized by two sperms.
c. The egg producing cells fail to divide properly
and so the mature egg contains a double set of
chromosomes.

18. TRIPLOIDY

19. TETRAPLOIDY
 Two extra chromosome set are present. So a cell
contains 92 chromosomes.
 Not compatible with life.

20. TETRAPLOIDY

21. STRUCTURAL
ABERRATIONS

22. DELETION
 It means of loss of small portion of chromosome
 occurs from breakage at random in both
chromatids of a chromosome(chromosome
break), or only in one chromatid (chromatid
break).

23. DELETION

24. TRANSLOCATION
 Sometimes a segment of a chromosome becomes
detached and unites with another non- homologous
chromosome.
 It is of two types:
i. Simple translocation
ii. Reciprocal translocation

26. RECIPROCAL TRANSLOCATION

27. INSERTION
 A fragment is transferred from a chromosome to a
non homologous chromosome.
 It is a rare non reciprocal type of translocation
which involves three breaks.

28. INSERTION
x y
z

29. INVERSION
 It results when there are two breaks in a
chromosome and the detached segment becomes
reinserted in the reverse order.
 It is of two types depending upon inclusion or
absence of centromere.

30. A. Paracentric- both breaks in one arm of
chromosome
B. Pericentric- it has breakpoints on either side of
the centromere.

31. INVERSION

32. ISOCHROMOSOME
 It is a chromosome that has lost one of its arm and
replaced it with an exact copy of the other arm.

34. RING CHROMOSOME
 It was first discovered by Lilian Vaughan in 1926.
 It is a chromosome whose arms have fused
together to form a ring.
 It is denoted by symbol ‘r’ in human genetics.

35. RING CHROMOSOME

36. DUPLICATION
 The term "duplication" simply means that a part of a
chromosome is duplicated, or present in two copies.
 This results in having extra genetic material, even
though the total number of chromosomes is usually
normal.
 Since a very small piece of a chromosome can contain
many different genes, the extra genes present in a
duplication may cause those genes to not function
properly

37. DUPLICATION
 These "extra instructions" can lead to errors
in the development of a baby.
 One example of a genetic syndrome caused
by a duplication is called "Pallister Killian
syndrome," where part of the #12
chromosome is duplicated.

38. DUPLICATION

39. SUMMARY AND CONCLUSION