Homocystinuria

What this deck covers

Homocystinuria in twelve clinical teaching cases with worked explanations. Each case gives you a clinical vignette, four options, the correct answer, and an explanation of why each of the other three is wrong.

Diagnoses and management options tested

Across the twelve cases you are asked to choose between options such as: MTHFR (methylenetetrahydrofolate reductase) deficiency, Cystathionine beta-synthase (CBS) deficiency, Pyridoxine-dependent epilepsy, Maple syrup urine disease (MSUD), MTHFR deficiency, Marfan syndrome, Ehlers-Danlos syndrome, Joint hypermobility and aortic root dilatation, Upward lens dislocation and tall stature, Autosomal dominant inheritance pattern, Cystathionine beta-synthase (CBS), Methionine synthase (MTR), Methylenetetrahydrofolate reductase (MTHFR), Betaine-homocysteine methyltransferase (BHMT), Conversion of homocysteine to cystathionine, Conversion of methionine to SAM, Conversion of 5,10-methylene-THF to 5-MTHF, Conversion of SAM to SAH, Phenylketonuria (PKU), Propionic acidemia, MTHFR deficiency / homocystinuria, Plasma total homocysteine plus MTHFR gene sequencing, Aortic root dilatation with acute dissection, Hypertrophic cardiomyopathy with outflow obstruction, Thromboembolic stroke due to hyperhomocysteinaemia, Paradoxical embolism through a patent foramen ovale.

Clinical pearls from this deck

• The methionine level decides it. Markedly elevated homocysteine with LOW methionine and low CSF 5-MTHF is a remethylation defect — MTHFR deficiency. Homocysteine cannot be remethylated back to methionine, so it accumulates while methionine falls.
• CBS deficiency is the commonest cause of classic homocystinuria, raising both homocysteine AND methionine. The ocular signature is inferonasal (downward and inward) lens dislocation, and it typically declares itself in childhood or adolescence.

The twelve worked cases in this deck, with the images and the full explanation of every option, are part of Pediatric Case Review membership. See what is included.

More from this system: all metabolic and genetic decks and question sets · pediatric reference values.