4. Features of Klinefelter Syndrome
• Tall stature; thin build;
long lower limbs
• Testicular atrophy
• Female pattern of pubic
hair
• High pitched voice
• Infertility
(aspermatogenesis)
• Gynaecomastia
• Low level of intelligence
• Serum testosterone
levels low to normal
• FSH and LH levels very
high
• Sex chromatin positive
8. Features of Triple X Syndrome
• Normal in appearance
• Difficulty in speech,
learning and emotional
responses
• Mild mental retardation
in 15-25% cases
• Two sex chromatin
Barr bodies
• Infertility
• Wide-set eyes
• Amenorrhoea
• Expressionless face
• Enamel hypoplasia
• Deficient language
skills
• Delayed development
of motor skills
11. Double Y Syndrome
• Chromosome complement: 47,XYY
• Phenotype: Male
• Incidence: 1:1000
12. Features of Double Y Syndrome
• Normal in appearance
• Tall stature
• Aggressive behaviour
• Problems in motor and language
development
13. Monosomies of Chromosomes
• Presence of only one member of a chromosome
pair in a karyotype
• More detrimental than equivalent trisomy
• Can involve autosomes or sex chromosomes
• Usually abort spontaneously
• Monosomy of X chromosome results in XO
condition called Turner syndrome
15. Features of Turner Syndrome
• Short statured female
• Sexual infantilism with
primary amenorrhoea
and sterility
• Short, webbed neck
• Prominent ears with
defective hearing
• Small mandible
• Defective vision
16. Features of Turner Syndrome
• Epicanthal folds
• Low posterior hair line
• Cubitus valgus
• Broad chest with widely
spaced nipples
• Cardiovascular
anomalies
• Hyperconvex finger
nails
• Pigmented nevi
• Sex chromatin negative
19. Structural Chromosomal Abnormalities
• Results from chromosome breakage
• Followed by reconstitution in an
abnormal combination
• Breaks in any chromosome may be
induced by various factors
37. REFERENCES
1. Essentials of Anatomy for Dentistry
Students,1st Edition.
2. Langman’s Medical Embryology,11th
Edition.
3. Human Embryology, 5th Edition.
39. MCQs
2. Testicular atrophy is associated with:
a) Triple X syndrome
b) Double Y syndrome
c) Turner syndrome
d) Klinefelter syndrome
40. MCQs
3. Sex chromatin negative is a characteristic
feature of:
a) Triple X syndrome
b) Down syndrome
c) Turner syndrome
d) Klinefelter syndrome
41. MCQs
4. All of the following are trisomy of sex
chromosomes except:
a) Turner syndrome
b) Klinefelter syndrome
c) Triple X syndrome
d) Double Y syndrome
42. MCQs
5. Partial deletion of short arm of chromosome
5 is a feature of:
a) Angelman syndrome
b) Prader -Willi syndrome
c) Cri-du-chat syndrome
d) All of the above