Mitochondrial Disorders Flashcards

1
Q

How many genes make up mitochondrial DNA

A

37 Genes

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2
Q

How is mitochondrial DNA organized

A

double stranded ring, no introns, no homologous recombination or meiosis

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3
Q

The majority of genes that contribute to the ETC come from _ DNA

A

nuclear

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4
Q

Which complex of the ETC is entirely nuclear encoded

A

Complex II

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5
Q

How many nuclear genes contribute to mitochondrial function

A

over 1200

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6
Q

Leigh syndrome is also referred to as

A

Subacute necrotizing encephalomyelopathy

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7
Q

Leigh syndrome is characterized by

A

the degeneration of the central nervous system (brain, spinal cord, and optic nerve)

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8
Q

Clinical features of Leigh syndrome

A

Leukodystrophy on MRI
DD/ regression
Ataxia, spasticity, hypotonia
neuropathy
nystagmus
opthalmoparesis
optic atrophy, RP
dysphagia
HCM
Deafness

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9
Q

Onset of Leigh syndrome

A

3-12 months

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10
Q

Genes associated with Leigh Syndrome

A

> 75
most common: SURF1
MTATP6, PDHA1, BTD

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11
Q

NARP (Neuropathy, Ataxia, and Retinitis Pigmentosa) Clinical features

A

Salt and pepper retinopathy
DD
Numbness, tingling or pain in the extremities
Balance/coordination problems
Proximal muscle weakness
vision loss/light sensitivity
hearing loss
seizures
cardiac conduction defects

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12
Q

Onset for NARP

A

Adolescence or young adulthood

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13
Q

High levels of heteroplasmy with NARP may cause

A

Leigh syndrome

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14
Q

MELAS

A

Mitochondrial encephalopathy, Lactic Acidosis, and Stroke-Like Episodes

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15
Q

Clinical features of MELAS

A

“Stroke-like” episodes: seizures, headaches, encephalopathy, dementia
elevated lactic acid in blood and CSF
muscle weakness, exercise intolerance
cortical vision loss
hemiparesis
vomiting
hearing loss
short stature
DM
Peripheral neuropathy

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16
Q

MELAS MRI

A

do not have the classic vascular findings as in stroke
asymmetric, increased T2 signal
typically, posterior cerebrum

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17
Q

Leigh syndrome MRI

A

Bilateral, symmetrical hypintensities in the basal ganglia or brainstem

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18
Q

MIDD

A

Maternally Inherited Diabetes- Deafness (MIDD)

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19
Q

Clinical features of MIDD

A

rapid and severe bilateral sensory hearing loss typically in the 20s-30s
DM develop later in the third decade

20
Q

MIDD is more commonly prevalent in what population

A

Japanese

21
Q

this mutation makes up 85% of MIDD cases

A

m.3243A>G

22
Q

MERRF

A

Myoclonic Epilepsy with Ragged Red Fibers

23
Q

Clinical Features of MERRF

A

myoclonus, CNS deterioration (seizures, ataxia
Short stature
Cardiomyopathy; dysthymias
hearing loss
ophthalmoplegia
exercise intolerance
peripheral neuropathy

24
Q

biochemical finding of MERRF

A

Increased lactate and pyruvate in blood and CSF- increases after exercise

25
Q

Muscle biopsy finding of MERRF

A

Ragged red fibers

26
Q

LHON

A

Leber Hereditary Optic Nueropathy

27
Q

LHON clinical features

A

Vision loss (bilateral blurring and clouding of vision)
tremors, neuropathy
arrhythmia

28
Q

Common variants for LHON

A

m.11778G>A, m.3460G>A, m.14484T>C

29
Q

LHON is more common in

A

Males

30
Q

Pearson Syndrome

A

Sideroblastic anemia,
bone marrow failure
exocrine pancreatic failure
renal fanconi syndrome
lactic acidosis

31
Q

Key findings for Pearson syndrome

A

weakness, fatigue, frequent infections, easy bruising, failure to thrive, liver and kidney failure

32
Q

Kearns Sayre

A

retinopathy, rod-cone dystrophy, ptosis, ophthalmoplegia
adrenal insufficiency
cardiac conduction defects
ataxia
endocrine dysfunction- diabetes
hypothyroidism
adrenal insufficiency
Sensory neural hearing loss
Failure to thrive

33
Q

CPEO

A

Chronic Progressive External Opthalmoplegia

34
Q

CPEO clinical symptoms

A

Pstosis
ophthalmoplegia
proximal limb weakness

exercise intolerance, myopathy, dysphagia

35
Q

MNGIE

A

Mitochondrial Nuerogastrointestinal Encephalopathy Disease

36
Q

Clinical features of MNGIE

A

Dysmotility (nausea, dysphagia, reflux, pain, diarrhea, emesis)
Cachexia
Ptosis/ opthalmoplegia
Leukoencephalotpathy
demyelinating peripheral neuropathy
distal weakness

37
Q

Onset of MNGIE

A

variable with mean onset of 18

38
Q

Gene associated with MNGIE

A

TYMP

39
Q

Biochemical marker for MNGIE

A

elevated plasma thymidine and deoxyuridine or enzymatic analysis of thymidine phosphorylase

40
Q

POL-G related disorders

A

alpers-huttenlocher syndrome
childhood myocerebrohepatopathy spectrum
myoclonic epilepsy myopathy sensory ataxia
ataxia neuropathy spectrum
autosomal recessive/ dominant progressive external opthalmoplegia

41
Q

adult onset non syndromic sensorineural hearing loss gene

A

MT-RNR1

42
Q

childhood onset non syndromic sensiorneural hearing loss gene

A

MT-TS1

43
Q

Complex II deficiencies genes

A

SDHA, SDHB, SDHC, SDHD

44
Q

heteroplasmy increases in

A

rapidly dividing cells

45
Q

when seeing older patients its is useful to test

A

fibroblasts

46
Q

most common tissues to test

A

fibroblasts, muscle, hear, liver