Clinical Features and Molecular Diagnosis of Most Common Genetic Diseases

Question 1

the most common cause of
hypogonadism and infertility in males

and the most common sex
Cromosome aneuploidy in humans

Answer 1

Klinefelter Syndrome

Question 2

Klinefelter Syndrome
It is caused by

Answer 2

The extra X chromosome arises from a nondisjunction
in either the sperm or the egg.

Question 3

Klinefelter Syndrome
Clinical features

Answer 3

Tall
Hypogonadism, Infertility
Sexually underdeveloped
Reduced testosterone levels
50 % Gynaecomastia
Breast cancer 20 to 50 times more frequent.
Each additional X chromosome reduces the IQ by 10- 15 points, when comparing these persons with their normal siblings.
Delays in speech and motor skills as well as deficits in
attention, Learning disabilities and social skills.

Question 4

Complications
Klinefelter Syndrome

Answer 4

Behavioural problems anxiety, and depression
Increased risk of autoimmune disorders, breast cancer,
osteoporosis, leg ulcers and dental problems.

Question 5

XXX Syndrome
(Trisomy X)
Extra X chromosome due to

Answer 5

nondisjunction

Question 6

XXX Syndrome
(Trisomy X).
features of Triple X syndrome

Answer 6

Many girls and women with Triple X haveno signs symptoms. Signs and symptoms vary a lot but can include:
Physical:
- Tall/stature (height)
- Possible mild facial characteristics: (epicanthal
fold)microcephaly, curved fifth finger
Developmental:
Learning disabilities: (70%
The IQ are 10-15 points below siblings
Speech and language delays (50%)
Motor skills : poor coordination

Question 7

Turner syndrome
Maternal age is or not a predisposing factor?

Answer 7

not

Question 8

Turner syndrome
Clinical feature

Answer 8

Short stature
Congenital lymphedema
Widespread nipples
Shield chest
Horseshoe kidneys
Increased carrying angle of elbow (cubitus valgus)
Congenital hip dislocation
- Scoliosis
- Redundant nuchal skin
- Low posterior hairline
- Cardic lesion 40%
Coarctation of aorta
Bicuspid aortic valve
Cardiac conduction abnormalities
Hypoplastic left heart syndrome
- Gonadal dysgenesis (infertility, primary amenorrhea)

Question 9

Turner syndrome

Possible antenatal findings:
Possible neonatal features:

Answer 9

Cystic hygroma, ascites

webbed neck, coarctation of the aorta, renal anomalies
small size for gestational age, protruding ears, and lymphedema of the hands and feet,
although many newborns are phenotypically
normal 2

Question 10

Complications
Turner syndrome

Answer 10

Learning disabilities (in 70%)
Developmental delay (in 10%)
Hypothyroidism (acquired in 15-30%)
Type 2 diabetes mellitus (insulin resistance)

Strabismus, Cataracts
Recurrent otitis media
Sensorineural hearing loss
Inflammatory bowel disease
Celiac disease

Question 11

It is the most common abnormality of chromosomal number.

Answer 11

Down
Syndrome

Question 12

Down
Syndrome
Genetics

Answer 12

Nondisjunction (47, +21): 92.5%, The frequency of trisomy increases with increasing maternal age

Robertsonian translocation: 4.5%, not related to maternal age.

Mosaicism

Question 13

The most Common translocation leading ta Down
Syndrome involves chromosomes

Answer 13

14 and 21;
Robertsonian translocation