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My MCD- Genetics > Lecture 6- Diabetes > Flashcards

Lecture 6- Diabetes Flashcards

1
Q

How is insulin secreted by the pancreatic Beta cell?

A
  • Glucose enters Beta cell
  • Glucose is used to generate ATP
  • rise in ATP closes ATP dependent K+ channels
  • membrane depolarises
  • VGCC open and Ca2+ influx
  • vesicles containing insulin fuse with membrane + exocytosis
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2
Q

Name two monogenic types of diabetes

A

Maturity onset diabetes of the young (MODY)

Permanent neonatal diabetes (PND)

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3
Q

What is the inheritance of MODY?

A

Autosomal dominant monogenic

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4
Q

Name two genes that might cause MODY and explain their function

A

HNF-1alpha (hepatic nuclear factor) = TF

Glucokinase = Enzyme

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5
Q

What is the function of HNF1-alpha?

A

A transcription factor stimulating insulin production

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6
Q

What happens when HNF1-a is mutated?

A
  • Insulin production is reduced because ATP sensitive K+ channel doesn’t close
  • Manifests in adulthood when B-cell function declines naturally
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7
Q

What can be used to manage MODY?

A

sulphonylurea- which causes the K+ channel to close

May require insulin therapy

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8
Q

What might be the complications of MODY?

A

microvascular and microvascular complications

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9
Q

What is the function of glucokinase?

A
  • An enzyme converting glucose to G6P which works around 4mmol/l
  • involved in Beta cell glucose sensing
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10
Q

What do mutations in glucokinase cause?

A

Higher set point at which insulin secretion is triggered

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11
Q

What are the clinical features of gluocokinase MODY?

A
  • stable, mild hypoglycaemia
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12
Q

What is the treatment for GCK MODY?

A
  • Do not need treatment, don’t really have long term complications
  • Diagnosis of GCK MODY instead of T1D means treatment can be stopped
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13
Q

Name two rarer types of mutations causing MODY and their clinical manifestations

A

1) HNF4-a: older age of onset, low renal glucose threshold, macrosomia and transient neonatal hypoglycaemia
2) HNF-1B: Renal cysts and diabetes, genital tract mutation

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14
Q

What is Permanent Neonatal Diabetes?

A
  • Diabetes in the first 6 month of life
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15
Q

Which genes are mutated in PND?

A

KCNJ11, ABCC8 and INS

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16
Q

What happens when KNCJ11 is mutated?

A

ATP sensitive channels do not close, membrane remains hyper polarised, insulin filled vesicles not exocytosed

17
Q

What is the treatment for PND? and how does it wok

A
  • sulphonyureas

- binds to and closes ATP channel = ATP independent closure

18
Q

What causes monogenic diabetes?

A
  • Single nucleotide changes causing:
  • missense, frameshift, nonsense
  • autosomal dominant but maybe recessive
19
Q

What are the two types of DNA sequencing methods?

A

Sanger and Next Gen sequencing

20
Q

What is the key difference between Sanger sequencing and NGS?

A

NGS sequences multiple genes simultaneously but Sanger sequences one gene at a time so it has high precision

21
Q

How is mitochondrial diabetes inherited?

A

Maternally

22
Q

Which mitochondrial disorders feature diabetes?

A

MIDD- maternally inherited diabetes and deafness

MELAS- myopathy, encephalopathy, latic acidosis, stroke like episodes

23
Q

What is heteroplasmy

A

Variable phenotype caused by variable load of mt

24
Q

What are the general features of mitochondrial disorders?

A
  • diabetes
  • young- onset sensorineural deafness
  • high lactate
  • muscle aches
  • short stature
25
Q

What is necessary for polygenic diabetes?

A
  • an environmental factor

- lifestyle aspect

26
Q

What is polygenic diabetes?

A

A compilation of genetic changes that increases your predisposition to developing T1D and T2D

27
Q

What is the purpose of GWAS studies?

A

To see if a disease is statistically associated with Single Nucleotide Polymorphisms

28
Q

What did GWAS studies in T2D show?

A
  • around 90 loci are associated with increased risk
  • SNPs account for 6% of T2D risk
  • most affect B cel function
29
Q

What is the relationship between diabetes and obesity?

A

Have copy number variants in obesity and there might be an increased risk of diabetes with CNVs but not sure. More like to be related to single nucleotide changes

30
Q

What is precision medicine and why could it be useful?

A
  • Using genetic information to provide targeted therapy
  • Diagnosis
  • Treatment

My MCD- Genetics (6 decks)

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