Inborn errors of metabolism

Question 1

Pathogenesis of phenlketonuria (3)

Answer 1

absent phenylalanine hydroxylase enzyme which converts phenylanlanine> tyrosine/dopamine/melanine/adrenaline/NA
leads to decreased dopamine and protein synthesis and demyelination
elevated serum phenylalanine levels>neurotoxic biproducts

Question 2

Presentation of phenylketonuria (5)

Answer 2

Musty urine
low IQ/developmental delay
hypopigmentation
seizures
eczema

Question 3

Ix for phenylketonuria

Answer 3

measure blood phenylalanine levels

Question 4

Mx of phenylketonuria (2)

Answer 4

remove all protein from diet and replace w. supplements containing no phenylalanine
regularly monitor plasma phenylalanine levels

Question 5

Associations of phenylketonuria (4)

Answer 5

anxiety
depression
phobias
less masculine self-image

Question 6

Council PKU mother on…(4)

Answer 6

facial dysmorphism
low IQ
growth retardation
microcephaly

Question 7

pathogenesis of homocysteinuria

Answer 7

elevated blood and urine concentration of homocystein (sulphur-containing AA) due to defect in cystothionine synthase deficiency.

Question 8

Presentation of homocysteinuria (8)

Answer 8

normal at birth
cataracts
downward subluxation of ocular lens
progressive learning difficulty, psychiatric disorders and convulsions
friable hair
paraplegia
developmental delay
emboli

Question 9

Mx of homocysteinuria (2)

Answer 9

50% respond to high-dose pyridoxine (B6)

those who don’t have low methionine diet (cysteine precursor) with cysteine supplementation.

Question 10

Pathology of galactosaemia (2)

Answer 10

defect in galactose-1-phosphate uridyl transferase

cannot breast feed baby

Question 11

Presentation of galactosaemia (4)

Answer 11

Cataracts
illness from lactose-containing milks
vomitting, lethargy, poor wt. gain
episodes of E.coli sepsis