Inborn errors of metabolism

Question 1

A defect in the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) →
impaired conversion of hypoxanthine to IMP and guanine to GMP →
excess uric acid & ↑ de novo purine synthesis

Answer 1

Lesch-Nyhan syndrome

Question 2

Usually asymptomatic for the first 6 mo

Orange sand-like sodium urate crystals in urine
hyperuricemia→ Gouty arthritis→ Renal failure
Developmental delay/cognitive impairment
Muscle dystonia/ spasticity

Answer 2

Lesch-Nyhan syndrome

Aggression, self-injurious behavior

Question 3

↑ Carbamoyl phosphate
↑ Orotic Acid
↓/absent Citrulline

what enzyme is deficient?

Answer 3

OTC deficiency

Ornithine transcarbamylase

Question 4

Carbamoyl phosphate synthetase I deficiency causes

Answer 4

↓ Orotic acid

Question 5

How to treat Lesch Nyan

Answer 5

Allopurinol
or
Febuxostate

(Block Xanthine Oxidase)

Question 6

How to treat OTC deficiency

Answer 6

Strict low-protein diet

Question 7

Urea cycle disorder:
Nausea, vomiting, irritability, poor feeding
Delayed growth and cognitive impairment

In severe cases, metabolic encephalopathy with coma and death

Answer 7

OTC deficiency

Question 8

N-acetylglutamate synthase deficiency

Prognosis

Answer 8

Fatal is untreated

Like CPSI deficiency