1. Human Genetics

2. Chromosomal Disorders
Nondisjunction – means “not coming apart”; when homologous chromosomes fail to separate, abnormal chromosome numbers may find their way into gametes
Monosomy – missing one chromosome from a pair
Trisomy – having three copies of a chromosome
Ex] Trisomy 21 – extra chromosome-21

3. A karyotype displays a diploid number of chromosomes.
Analyzing Karyotypes
A karyotype displays a diploid number of chromosomes.

4. How Are Karyotypes Made?

5. Human Female Karyotype
Human Karyotypes
Human Female Karyotype
Notation: 46, XX
Autosomes
Sex Chromosomes
Notation: 46, XY

6. Karyotype Analysis Is this person a male or a female?
What condition does this person have?
Trisomy 21 / Downs Syndrome
What was it caused by?
Nondisjunction 
What notation would you use to characterize this patient’s karyotype?
47, XY, +21

7. Recognizing Disorders in Karyotypes

8. Patient 1

9. Patient 2
Turner’s Syndrome

10. Patient 2 Short stature (height) Failure of ovaries to develop
Abnormal fingernails and toenails.
Kidney and urinary tract disorders.
Hearing problems.
Drooping eyelids.
Wandering eyes.

11. Patient 3
Cri-Du-Chat

12. Cri Du Chat Patient 3 Cry is high-pitched so it sounds like a cat.
Low-set or abnormally shaped ears.
Mental retardation
Webbed fingers and toes.
Small head
Wide-set eyes

13. Patient 4
Klinefeleter’s Syndrome

14. Patient 4 Very little body hair. Underdeveloped muscles
Enlarged breasts
Reduced speech ability
Reduced problem-solving skills.
Trouble with controlling impulses

15. XXX Syndrome Patient 5 Very tall Often has learning disabilities
Delayed learning in speech, language.
Delayed motor skills.

16. Patient 5

17. Trisomy 13: Patau’s Syndrome
Patient 6
Trisomy 13: Patau’s Syndrome

18. Patient 6 Extra fingers and toes Deformed, rocker-bottom feet.
Severe mental deficiency due to underdeveloped brain.
Facial deformation such as cleft palate.
Heart and Kidney defects.

19. Trisomy 18: Edward’s Syndrome
Patient 7
Trisomy 18: Edward’s Syndrome

20. Edward’s Syndrome Patient 7 Mental retardation
Small head, very wide-set eyes, small lower jaw.
Small eyes.
Bones are severely retarded in their growth (they grow slowly)
Urinary tract, digestive tract, and genitals are malformed.

21. Patient 8
Trisomy 21: Down’s Syndrome

22. Down’s Syndrome Patient 8
Flat face with an upward slant to the eye, short neck, and abnormally shaped ears.
Hearing problems.
Heart disease
Intestinal problems
Thyroid dysfunctions
Skeletal problems
Dementia