Chromosomal Abnormalities

Question 1

What is trisomy 13 also known as?

Answer 1

Patau syndrome

Question 2

What is the chromosomal abnormality associated with Patau syndrome?

Answer 2

47, XX or XY, +13

Question 3

What are the clinical features of patau syndrome?

Answer 3

• Cleft lip/palate
• Low set ears
• Small chin
• Micropthalmia
• Polydactyly
• Rocker-bottom feet
• Congenital heart defects - VSD and PDA in particular

Remember 7 Ps - 7 Ps of Patau syndrome: holoProsencephaly, cleft liP and Palate, Polydactyly, Pump disease (congenital heart disease), Polycystic kidney disease, cutis aPlasia.

Question 4

What syndrome might the following be associated with?

Answer 4

Coloboma - associated with trisomy 13 (Patau Syndrome)

Question 5

What cardiac defects are commonly seen in Patau syndrome?

Answer 5

VSD and PDA

Question 6

What is the epnymous name for trisomy 18?

Answer 6

Edwards syndrome

Question 7

What is the chromosomal abnormality seen in Edwards syndrome?

Answer 7

♀: 47,XX,+18
♂: 47,XY,+18

Question 8

What are the clinical features of edwards syndrome?

Answer 8

• Low set ears
• Micrognathia
• Prominent occiput
• Microcephaly
• Broad nose
• Rocker bottom feet
• Heart defects - VSD, ASD and tetralogy
• Severe learning disability
• Clenched fists

PRINCE Edward turned 18: Prominent occiput, Rocker-bottom feet, Intellectual disability, Nondisjunction (in meiosis), Clenched fists, low-set Ears, and chromosome 18.

Question 9

How can you distinguish Edwards from Patau syndrome?

Answer 9

Edwards has:
* Polydactyly
* Coloboma
* Small eyes and head
* PDA
* Cleft lip/palate

Patau has:
* Clenched fists
* Small chin
* Rocker bottom feet

Question 10

What cardiac abnormalities does Patau syndrome have?

Answer 10

• VSD
• ASD
• Tetralogy of fallot

Question 11

What causes turners syndrome?

Answer 11

It is caused by either the presence of only one sex chromosome (X) or a deletion of the short arm of one of the X chromosomes.

Question 12

What is the pathophysiology of turners syndrome?

Answer 12

chromosomal nondisjunction → X chromosome monosomy/mosaicism → impaired ovarian development → malfunctioning streak gonads with connective tissue instead of normal germ cells → estrogen and progesterone deficiencies

Question 13

Does turners syndrome affect males, females or both?

Answer 13

Females - given affect X chromosome

Question 14

What are clinical features of turners syndrome?

Answer 14

Female phenotypoe
* Primary ovarian insufficiency - delayed puberty, Primary amenorrhoea, infertility
* Cystic hygroma/lymphoedema
* Short stature
* Shield chest
* Webbed neck
* High arched palate
* Cardiac abnormalities - aortic dissection, coarctation of aorta, bicuspid aortic valve
* Hypothyroidism, T2DM
* Horseshoe kidney

Question 15

How does Turners syndrome present in terms of sex hormone profile?

Answer 15

Hypergonadotrophic hypogonadism - ↓ estrogen, ↓ androgens, ↑ FSH, ↑ LH

Question 16

What disorders are associated with webbed neck deformity?

Answer 16

Noonans and turners syndrome

Question 17

What cardiovascular abnormalities are associated with turners syndrome?

Answer 17

• Coarctation
• Aortic aneurysm
• Bicuspid Aortic Valve

Question 18

What causes klinefleters syndrome?

Answer 18

Usually due to nondisjunction of sex chromosomes during meiosis - 47,XXY (rarely 48,XXXY or 48,XXYY)

Question 19

What are the clinical features of klinefleters syndrome?

Answer 19

• Testicular dysgenesis
• Gynaecomastia
• Azoospermia
• Micropenis
• Osteoporosis