Sims genetics

16. How many autosomes:?
–22 pair
How many sex chromosomes?
–1 pair
Females:
–46 XX
Males:
–46 XY

17. Normal human karyotype is
– Diploid.
Sperm/ Eggs are
– Haploid (carry one copy of each
chromosome).
The sex of newborn is determined by
– Sperm

18. GENETIC ENVIRONMENTAL
Hemophilia
Osteogenesis imperfecta
Phenylketonuria
Galactosaemia
Duchene
muscular
dystrophy
Spina bifida
Ischemic heart disease
Ankylosing spondylitis
Scurvy
Trauma
Tuberculosis
Peptic ulcer
Diabetes mellitus

19. *HEREDITARY:
Transmitted in the germ line; passed from parents to their
offspring.
*FAMILIAL:
Diseases run in families and represent multifactorial
inheritance. Risk for first degree is 5-10% higher.
*CONGENITAL:
Born with; disease present since birth.

20. BARR BODY
[ SEX CHROMATIN ]
Nucleus
Barr body
# of Barr bodies = # of X chromosomes - 1

28. Davidson Body

31. LYON HYPOTHESIS:
[ 1961, Mary Lyon ]
1. Only one of the X - chromosomes is
genetically active,
2. Other X of either maternal or
paternal origin undergoes
heteropyknosis and is rendered
inactive.

32. 3. Inactivation of either the maternal or
paternal X occurs at random among all
the cells of the blastocyst on or about
the 16th day of embryonic life.
4. Inactivation of the same X
chromosome persists in all the cells
derived from each precursor cell.
LYON HYPOTHESIS:

34. INCIDENCE:
• 1 in 800 live births [ overall ]
• Maternal age:
•< 20 yrs - 1 in 1550,
•> 45 yrs - 1 in 30

39. Flat face
Protruding tongue
Occiput tends to be flat
Low bridged nose
Oblique palpabral
fissure
Epicanthic folds
Slanting eyes
Brushfield spots in iris

40. Epicanthic fold:

41. Simian crease

43. 40%- Congenital cardiac defects
ASD, VSD, TOF, PDA.
10-20 fold risk to develop Acute leukemia's:
ALL/AML.
CNS:
Mental retardation, IQ -30.
Develop Alzheimer’s disease -
-- at very young age;
Intestine:
Imperforate anus, duodenal stenosis, Hirschsprung’s
disease.
Sterility:
Arrested spermatogenesis.

44. Life expectancy:
Most common cause of death:
Congenital heart diseases and leukemia.
With normal heart, only 5% of children with
Down syndrome die before age 10.
After age 10, the estimated life expectancy
is 55 years.

46. Common cause of male hypogonadism
and infertility.
1 in 1000 live male births,
Presence of one or more extra X
chromosome, 47 XXY.
Rarely diagnosed before puberty,

47. Clinical features:
Eunuchoid body habitus:
– Long legs, tall and thin.
Small, atrophic testes, small penis.
Lack of secondary sexual characteristics,
Deep voice of high pitch.
Gynecomastia, feminine characters.
IQ - low; mental retardation, behavioral
abnormality.

50. Karyotype of KFS

52. Turner Syndrome:
Most common sex chromosome
abnormality in females,
Monosomy X; the missing chromosome X
is usually of paternal origin.
Incidence: 1/8000 . Most die in infancy

53. Karyotype of Turner Syndrome:

54. Clinical features of TS:
Edema of dorsum of hand & foot,
Bilateral neck webbing,
Congenital heart diseases, (COA)
Short stature, hyper convex finger nails.
Broad chest & widely spaced nipples,
Multiple Pigmented nevi,
Amenorrhea [ Primary ],
Infertility, streak ovaries.
Low posterior hair line.
Wide carrying angle (cubitus valgus).

57. Cystic hygroma of neck > webbed neck

59. Lymphedema

60. Streak ovaries

61. True Hermaphrodite:
( ovary + testis )
Pseudo Hermaphrodite:
( Disagreement between
phenotypic and
gonadal sex )

64. Pseudo hermaphrodite
Female pseudo hermaphrodite:
* Ovaries,
* Male external genitalia,
Male pseudo hermaphrodite:
.. Testes,
.. Female external genitalia;

65. MENDELIAN
DISORDERS:
[ MUTANT GENES WITH
LARGE EFFECT ]
Genetic diseases:

66. 66

67. 67

68. 68

69. 69

70. 70

71. 71

72. 72

73. 73

74. 74

75. 75

76. 76
Class I Loss of receptor synthesis
Class II Transport inside cell is impaired
Class III Failure of receptors to bind LDL
Class IV Fail to internalize after binding
Class V Internalized bodies are trapped in
endosomes

77. 77
MUTATION IN ENZYME PROTEIN
PHENYLKETONURIA
GALACTOSEMIA
LYSOSOMAL STORAGE DISEASES
GLYCOGEN STORAGE DISEASES

78. 78
DISEASE ENZYME DEFICIENCY
Pompe’s Disease Lysosomal Glucosidase
Tay Sachs disease Hexosaminidase A
Gaucher disease Glucocerebrosidase
Niemann Pick disease Sphingomyelinase
Hurler disease L-Iduronidase
Hunter disease L-Iduronosulphate
sulphatase

79. 79

80. 80

81. 81

82. 82

83. 83

84. 84

85. 85

86. 86