Genetic Conditions and Patterns of inheritance

Question 1

Hereditary haemochromatosis

Answer 1

Autosomal recessive - HFE gene chromosome 6.

Excessive intestinal absorption of dietary iron resulting in a pathological increase in total body iron stores - build up in organs

Question 2

Huntingdon’s disease

Answer 2

Autosomaldominant

Question 3

Tay-Sachs disease

Answer 3

Autosomal recessive

Question 4

Ehlers Danlos

Answer 4

Mostly autosomal dominant

Question 5

Alport’s syndrome

Answer 5

Most (about 85%), the condition is inherited in an X-linked pattern

Question 6

Sickle cell

Answer 6

Autosomal recessive

Question 7

Haemophilia

Answer 7

X-linked

Question 8

Duchenne muscular dystrophy

Answer 8

X-linked

Question 9

Cystic fibrosis

Answer 9

Autosomal recessive

Question 10

Thalassaemia

Answer 10

Autosomal recessive

Question 11

Autosomal dominant polycystic kidney disease (ADPKD)

Answer 11

Autosomaldominant

Question 12

Type 1 neurofibromatosis

Answer 12

Autosomaldominant

Question 13

Tuberous sclerosis

Answer 13

Autosomaldominant

Question 14

Turner syndrome

Answer 14

Only affects females and is caused by a missing or abnormal X chromosome

Question 15

Klinefelter’s syndrome

Answer 15

Only affects males and is caused by an extra X chromosome

Question 16

Patau’s syndrome

Answer 16

Extra copy of chromosome 13

Question 17

Down’s syndrome

Answer 17

Extra copy of chromosome 21

Question 18

Fragile X syndrome

Answer 18

X-linked

Question 19

Edwards’ syndrome

Answer 19

Extra copy of chromosome 18

Question 20

Alpha-1 antitrypsin deficiency (α1-antitrypsin deficiency, A1AD)

Answer 20

Autosomal co-dominant

Question 21

Charcot-Marie-Tooth

Answer 21

Autosomal dominant inheritance is the most common (but autosomal recessive, and CMT X-linked (CMTX) forms exist

Production of abnormal myelin: unstable and spontaneously breaks down –> demyelination–> slowing of conduction velocity.

Schwann cells proliferate and form concentric arrays of remyelination. Repeated cycles of demyelination and remyelination result in an ‘onion bulb’ appearance.