MCAD screening

Question 1

What are the three methods that maintain glucose homeostasis?

Answer 1

• Gluconeogenesis
• Glycogenolysis
• Fat oxidation

Question 2

What is MCAD deficiency?

Answer 2

• Medium chain acyl-coA dehydrogenase deficiency

- disorder of fatty acid oxidation that impairs body’s ability to break down medium chain fatty acids into acetyl-coA

Question 3

What are the clinical symptoms associated with MCAD deficiency?

Answer 3

• Hypoglycaemia
• Hypoketosis
• Lethargy, coma, death

Question 4

How does MCAD deficiency manifest?

Answer 4

• secondary accumulation of key metabolites
• dicarboxylic aciduria and octanoyl carnitine
• increased FFA:3-OHB ratio (3-hydroxybutyrate)

Question 5

What is the typical age of onset for MCAD deficiency?

Answer 5

• 1 yr of age

- often following a mild intercurrent infection or viral illness

Question 6

What was the previous lab method for detection of MCAD deficiency?

Answer 6

Urinary organic acid analysis

Question 7

What is the screening protocol for MCAD?

Answer 7

• Screen at day 5 (as for PKU)
• measure underived MRM C8
• if less than 0.5 = normal
• if greater than 0.5 then have a full scan Eluate
• if still greater than presume positive for MCADD

Question 8

What is the future method proposed for detection of MCADD?

Answer 8

MS/MS: widely adapted to detect internal errors of metabolism