Sunday, 14 November 2010

MRCP revision battle 49.1: Homocystinuria

Today is back to being a mixed set of battles with some familiar topics and some utterly unusual ones...

MRCP revision battle 49.1: Homocystinuria
MRCP revision battle 49.2: Nail-patella syndrome
MRCP revision battle 49.3: Golfers and Tennis Elbow
MRCP revision battle 49.4: Whipples disease
MRCP revision battle 49.5: Hypermagnesaemia
MRCP revision battle 49.6: Osteoporosis
MRCP revision battle 49.7: Osteogenesis Imperfecta

MRCP revision battle 49.1: Homocystinuria

Homocystinuria is an autosomally recessive inherited condition in which there is decreased activity of cystathionine beta synthase resulting in accumulation of homocysteine and methionine which interferes with collagen cross-linkage.

Features include:
  • Marfanoid body habitus
  • spontaneous retinal detachment
  • downwards lens dislocation
  • osteoporosis
  • venous and arterial thrombosis
  • low IQ

Diagnosis is with the cyanide nitroprusside test which detects elevated urinary homocysteine.

Treatment is:
  • methionine restriction
  • cysteine supplements
  • pyridoxine supplements

Now to nail-patella syndrome...