Nitrogen 3 Flashcards

1
Q

What usually causes an inherited metabolic disorder?

A

A defect in a single gene

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2
Q

What effect does an IMD cause?

A

Enzyme abscence of defieciency resulting in abnormal synthesis of amino acids, proteins, carbohydrates & lipids.

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3
Q

When do most IMDs present?

A

In infancy or childhood

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4
Q

What 3 effects do enzyme defects have on the reaction pathway?

A
  • A build up of precursor molecules
  • A decreased formation of product
  • An increased production of unwanted products (which may be toxic)
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5
Q

Where do a childs genes come from?

A

A child recieves one allele of each gene from each parent, giving them two alleles for every gene.

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6
Q

Define autosomal dominant inheritance:

A

The child requires just one defective allele to have the condition even if the other parent gave them a healthy allele

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7
Q

Define Autosomal Recessive Inheritance:

A

The child requires two defective alleles in order to present with the condition. this means some people will carry the defective gene without having the condition (carriers).

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8
Q

Which type of autosomal inheritence do most inborn errors of metabolism (IEMs) have?

A

Most IEMs have automsal recessive inheritance, i.e. heterozygous children are phenotypically normal.

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9
Q

How many IMDs are there in the urea cycle?

A

6, one for each important enzyme

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10
Q

Whats the most common IMD in the urea cycle?

A

Ornithine transcarbamoylase (OTC) deficiency

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11
Q

What kind of inheritance is occurs in urea cycle IMDs?

A

5 display autosomal recessive inheritance.

OTC is x-linked

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12
Q

What is X-linked inheritance?

A

Some genes are specific to the X or Y chromosome
X-linked inheritance refers to genes present only on the X chromosome.
This means boys will show the phenotype for whatever X chromosme they receive as they only have one
Girls will show typical dominant/recessive patterns for X-linked genes as they have two X chromosomes.

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13
Q

What is the main result of Urea cycle disorders?

A

A buildup of toxic ammonia. (Hyperammonaemia) which can cause accelerated breathing by stimulating a specific part of the brain and long term brain damage.

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14
Q

When do Urea cycle disorders typically present?

A

In newborns

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15
Q

Enzymes catalyse the conversion of amino acids to what 4 substances?

A

Hormones, Pigments, Amino Acids and neurotransmitters

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16
Q

What causes phenylketonuria (PKU)?

A

A deficiency in phenylalanine hydroxylase (PAH) deficieny).

17
Q

How is PKU inherited?

A

By automsomal recessive inheritenace

18
Q

What are the effects of PKU?

A

Insufficinet tyrosine for conversion to melanin and other products.
Build up of Phenylalanine and unwanted metabolites which build up in the nerves and cause abnormal brain development

19
Q

How is PKU treated?

A

A low-protein diet supplemented with tyrosine and protein substitutes.