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1

List the 7 types of congenital abnormalities and birth defects.

Malformation
Disruption
Dysplasia
Sequence
Association
Deformation
Syndrome

2

What is polysomy X in males and what are the clinical features?

Kleinfelter’s syndrome – tall, gynaecomastia, infertile, learning disability

3

What is monosomy X in females and what are the clinical features?

Turner Syndrome – webbed neck, infertile, normal intelligence, low posterior hairline

4

How can someone who has sex chromosomes XX be male?

Due to a translocation in which the sex determining region on the Y (SRY) has been translocated onto the X chromosome.

5

What are genomic disorders?

Disorders in which there is a gain or loss of DNA

6

Give an examples of two genomic disorders

Deletion – Di George syndrome
Duplication – Charcot-Marie-Tooth Disease Type 1A

7

What could be the potential future issues for someone who has a balanced translocation?

Balanced translocations lead to the formation of quadravalents (rather than bivalents) during meiosis which can lead to strange exchanges in genetic material which can cause disease

8

What are the 3 types of chromosome?

Metacentric
Submetacentric
Acrocentric

9

What are the three different types of chromosomal abnormality?

Aneuploidy
Structural
Mosaicism

10

Define dysplasia

Abnormal organisation of cells into tissue

11

What is the most common cause of Sequence e.g. Potter Sequence?

Oligohydramnios – reduced supply of amniotic fluid

12

Name three causes of Down Syndrome.

Non-disjunction during meiosis I or meiosis II
Robertsonian translocation –2 acrocentric chromosomes break at the centromere and fuses to form a new chromosome
Mosaicism

13

Describe how chromosome banding works.

Starts at 11 at the centromere – different banding for different stains

14

What is mosaicism?

The cells of an individual do not all contain identical chromosomes. There may be two or more genetically different populations of cells. E.g. one cell lineage will be Down Syndrome

15

What is the difference between a balanced and unbalanced translocation?

Unbalanced – there is a loss of genetic material

16

List some clinical features of Down Syndrome

Excess nuchal skin, sleepy, severe hypotonia, Single palmar crease, sandal gap Upwards slanting eye folds, macroglossia, Short stature, Cardiac abnormalities – ASD and VSD

17

Name two other trisomy disorders and describe symptoms.

13 – patau syndrome, 18 – Edwards