Biochem Lab Quiz 5

PKU stands for what?

Phenylketoneurine

What kind of issue is PKU?

Autosomal recessive on chromosome 11

What occurs when you have PKU?

missing enzyme (PAH) which causes buildup of PHE

What is PHE?

an essential amino acid

If there is a buildup in PHE then what occurs to tyrosine?

it decreases

What is tyrosine used for?

production of thyroid hormone and melanin

If there is an increase in PHE what occurs to thyroid hormone and melanin?

decreases in both leading to hypothyroidism and hypopigmentation

PHE toxicity due to an increase in it leads to what?

neurotoxicity and nephrotoxicity

What increases to try and get rid of PHE?

phenylpyruvic acid

Phenylpyruvic acid gets converted into what two acids and what affect?

phenylactic and phenylacetic

decrease pH

Phenylactic acid decreasing pH leads to what?

ketones in urine and further decrease in pH

Phenylacetic acid decreasing pH leads to what?

Mousy odor in urine

PHE does what in the blood brain barrier? What AA’s can’t pass?

attempts to take up all the entrances so only it can pass

tyrosine and tryptophan

Tyrosine decrease leads to what decreasing?

DOPA → dopamine

dopamine decrease causes what two hormones to decrease?

epinephrine and norepinephrine

Tryptophan decrease leads to a decrease in what?

serotonin

Decrease in serotonin, epinephrine and norepinephrine leads to what decreasing?

cognitive function, neurological development

brain mass and upper motor syndrome

How do you know if there is a decrease in neurological development?

eye following

Ways to diagnose PKU

PHE levels increased

Urinalysis shows low pH, ketons and mousy odor in urine

More ways to diagnose PKU

Genetic testing → PAH, BH4

Postnatal screenings

BH4 is used to do what?

Ensure PAH enzyme is functioning properly

What is the treatment of PKU?

BH4/Kuvan medication

Tyrosine supplements

Avoiding PHE → animal sources, nuts, soy

What are the most important BCAAs in MSUD (maples syrup urine)

Ile, Leu, Val

Accumulation of Ile, Leu, Val leads to what?

neurotoxicity

Defective BCKDH in MSUD leads to what?

accumulation of BCAA and alpha-ketoacids (metabolic acidosis)

decrease in Acetyl-CoA

Breast feeding has what properties?

catabolic stress and endogenous catabolism

Breast feeding can lead to more what?

neurotoxicity and metabolic acidosis

Babies rely on what as their primary energy source?

fat and ketones

Breast milk is what?

ketogenic

What is protein used for in babies?

growth and development

Lethargy, poor feeding, hypotonia and burnt sugar odor are symptoms of what?

maple syrup urine disease

What happens we have lack BCKDH?

we can not break down endogenous BCAAs that are released

Can leucine be broken down into glucose?

no

How do you help a baby with MSUD?

giving them glucose and insulin

What occurs to a baby as proteolysis occurs?

BCAAs release

Acute phase managment of MSUD is what?

stopping protein intake

IV glucose and insulin

Dialysis (in metabolic crisis)

Chronic Management of MSUD?

lifelong low BCAA diet

medical formula low in Leu, Isoleucine, valine

thiamine supplementation

liver transplant

Is MSUD autosomal recessive or dominant?

autosomal recessive

What is the cause of MSUD?

a deficiency in BCKDH

What kind of foods should be consumed during MSUD?

Low protein foods: fats, sweets, and vegetables