X-linked mitochondrial disease

Question 1

X-linked disorders

Answer 1

1. Mutation on the X-chromosome
2. Mostly males affected
3. No male to male transmission

Question 2

X-linked Recessive Inheritance

Answer 2

1. Phenotype expressed in all males who carry the affected genotype
2. Phenotype expressed in homozygous females only
3. Heterozygote females are carriers

Question 3

X-linked Dominant Inheritance

Answer 3

Expressed in male hemizygotes and female heterozygotes

Question 4

Fragile X Syndrome

Answer 4

1. X-linked dominant
2. Trinucleotide repeat disorder- CGG
3. Most common cause of inherited developmental delay
4. Anticipation
5. Maternal transmission bias

Question 5

Fragile X clinical manifestations

Answer 5

1. Intellectual disabilities
2. Dysmorphic features: large ears, long face, macroorchidism
3. Autistic behavior
4. Social anxiety
5. Hand flapping/biting
6. Aggression

Question 6

Fragile X gene

Answer 6

FMR1

Question 7

fragile x chrom

Answer 7

xq27.3

Question 8

fragile x protein

Answer 8

FMRP

Question 9

FMRP function

Answer 9

Protein is essential form normal cognitive development and female reproductive function

Question 10

fragile x is cause by

Answer 10

Increase in the trinucleotide repeat number methylate the gene and the protein is not made

Question 11

X Chromosome Inactivation

Answer 11

1. Equal expression of X-linked genes
2. Random
3. Mosaic for maternal and paternal X chromosome
4. Does not occur in males

Question 12

Duchenne muscular dystrophy

Answer 12

1. Progressive muscular weakness proximal > distal
2. Calf hypertrophy
3. Dilated cardiomyopathy
4. CK levels 10x
5. Onset before the age of 5
6. Wheelchair bound before 13
7. Death in their 30’s
8. Absence of Dystrophin

Question 13

Becker Muscular Dystrophy

Answer 13

1. Progressive muscular weakness proximal > distal
2. Dilated cardiomyopathy
3. CK levels 5x
4. Onset later
5. Wheelchair bound after 16
6. Death in their 40’s
7. Abnormal quantity or quality of Dystrophin

Question 14

hemophilia A clinical manifestation

Answer 14

1. Spontaneous bleeds into joints, muscles or intracranial
2. Excessive bruising
3. Prolonged bleeding after injury or incision
4. Delayed wound healing

Question 15

hemophilia A gene

Answer 15

F8

Question 16

hemophilia A affects

Answer 16

factor VIII

deficiency in it

Question 17

hemophilia A chromosome

Answer 17

Xq28

Question 18

half of all hemophilia A are caused by

Answer 18

22A inversion

Question 19

Mitochondrial disease:

Answer 19

Group of disorders caused by dysfunction of the respiratory chain

These disorders tend to affect tissues that heavily rely on oxidative phosphorylation, brain, retina, skeletal muscle and heart

Question 20

mitochondrial disease exampels

Answer 20

Kearns-Sayre
MELAS
MERRF
Leber Hereditary Optic Neuropathy

Question 21

Kearns-Sayre, most commonly caused by`

Answer 21

somatic mutation