for all nursing students

1. GENETICS

2. Structure of chromosomes
 Chromosomes are the thread-like structure found
in the nuclei of both animal and plant cells.
 They are made of protein and one molecule of
deoxyribonucleic acid (DNA).
 In most of the organisms chromosomes are
arranged in pairs in the nucleus of the cell.
 We have 23 pairs of chromosomes.

3. PHYSICAL STRUCTURE
Size varies from 1 to 30 micron in length and diameter from 0.2
to 2 micron.
CENTROMERE:- The non-stainable part of the chromosome
making a primary constriction.
CHROMATIDS:- Two chromatids join at the centromere to form a
chromosome.
CHROMONEMA:- In each chromatid, there are two longitudinal
chromonemata coiled with each other.
SURFACE VIEW

4. TYPES OF CHROMOSOMES
1. TELOCENTRIC:- The centromere is
present at the end of the chromosomes.
2. ACROCENTRIC:-The centromere
is almost terminal. It has one large
and another very small arm.
LONG ARM
SHORT ARM
CENTROMERE
LONG ARM
CENTROMERE

5. 3. SUB-METACENTRIC:- Here the centromere
is not at the middle position of the
chromosomes. So the arms are unequal and it
is ‘L-Shaped’ in appearance.
4. METECENTRIC:- The centromere
is at the middle position. So the arms
are equal and it is ‘V-Shaped’ in
appearance.
LONG ARM
CENTROMERE
SHORT ARM
CENTROMERE
TWO EQUAL ARMS

6. Number
 Diploid : 46
 Haploid: 23 pairs
 Poliploid : Normal multiplication of
chromosomes
 1 from paternal and 1 from maternal and
fuse together to form 1 pair

7. Chromosomal abnormalities
 2 patterns
1. Numerical pattern
2. Structural pattern

8. PATTRENS
NUMERICAL
PATTERN
STRUCTURAL
PATTERN
- Triploid
- Tetraploid
- Aneuploid
- Translocation
- Deletion
- Inversion
- Ring chromosomes
- Isochromosomes

9. 1. Translocation
- Structural abnormalities take place in 2
chromosomes
- Usually genetic meterial is same but it alter or
it exchange
Types : Balanced reciprocal translocation
Robertsonian translocation

11.  DELETION
- Loss of part of chromosomes
1. Terminal deletion : distal part of the
chromosome is deleted
2. Interstitial deletion : in between
chromosome, any fragmentation or any part
is broken. Remaining part will fuse together

13. INVERSION
 There will be break in the chromosomes
 But not separated
 Genetic material will not transferred
Types: pericentric
Paracentric

15. Isochromosomes
 Abnormal split in the centromere
 Both arms will be separated

16. CHROMOSOMAL
ABNORMALITIES

22. Clinical Features
 Head and neck
 Brachycephaly
 Up-slanting palpebral
fissures
 Epicanthal folds
 Brushfield spots
 Flat nasal bridge
 Folded or dysplastic ears
 Open mouth
 Protruding tongue
 Short neck
 Excessive skin at the nape
of neck
 Extremities
 Short broad hands
 Short fifth finger
 Incurved fifth finger
 Transverse palmer crease
 Space between first and
second toe
 Hyper flexibility of joints

28. Diagnosis
 History collection
 Physical examination
 Genetic screening
 Amniocentesis
 Chorionic villa sampling
 AFP and HCG

30. Complications
 Aspiration
 Sleep apnea
 Heart problems
 Meningitis

31. Prevention
 Genetic counseling
 Premarital counseling
 Identification of risk category
 Prevention of elderly pregnancy

32. TRISOMY – 18 (EDWARDS
SYNDROME)

33. Definition
 Genetic Condition that causes severe
developmental delays due to extra
chromosome 18

34. Clinical features
 Small head
 MR symptoms
 Holoprosencephaly
(failure of the fore brain
to fuse
 Micro opthalmia (small
eye)
 Low IQ
 Clenched hands
 Loss of tears
 Drooling saliva
 Difficulty in feeding
 Omphalocele
 Absence of plantar
creases
 Uro-genital defect

36. Diagnosis
 History
 Physical examination
 Amniocenthesis

37. Complications
 Very poor prognosis
 Miscarriage
 Still birth
 80% of the children will die within 1 year

38. Management
 Supportive and symptomatic management
 Speech therapy
 Rehabilitation
 Corrective surgeries

39. KLEIN FELTER
SYNDROME

40.  It is a set of symptoms that results from two
or more X chromosomes in males
 The primary features are sterility and small
testicles

41. Clinical features
1. Physical development
2. Language development
3. Social development

42. Diagnosis
 History and physical examination
 Chromosomal analysis

43. Management
 Medical management
- Hormonal replacement therapy (TRT)
- Treatment for infertility
 Educational therapy
 Occupational therapy
 Speech therapy
 Behavior therapy

44. TURNER’S SYNDROME

45. Definition
 It is a chromosomal disorder in which
female child born with only one X
chromosomes
 Incidence: 1:8000

46. Clinical features
 Short structure
 Peripheral and lymph edema
 Webbing of the neck
 High arch palate associated with cleft
palate
 Small jaw
 Microretrognathia
 Absence of ovaries and menstruation
 Infertility
 CVS anomalies
 Renal anomalies

48. Management
 Hormonal replacement therapy
- Estrogen replacement therapy
 Supportive management