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Homocystinuria, also known as Cystathionine beta synthase deficiency, is an inherited disorder of the metabolism of the amino acid methionine, often involving cystathionine beta synthase. It is an inherited autosomal recessive trait, which means a child needs to inherit the defective gene from both parents to be affected.
Presentation[edit | edit source]
This defect leads to a multisystemic disorder of the connective tissue, muscles, CNS, and cardiovascular system. Homocystinuria represents a group of hereditary metabolic disorders characterized by an accumulation of homocysteine in the serum and an increased excretion of homocysteine in the urine. Infants appear to be normal and early symptoms, if any are present, are vague.
Symptoms[edit | edit source]
- A family history of homocystinuria
- Flush across the cheeks
- Tall, thin build
- Long limbs
- High-arched feet (pes cavus)
- Knock-knees (genu valgum)
- Pectus excavatum
- Pectus carinatum
- Mental retardation
- Psychiatric disease
- Eye anomalies:
-90% have ectopia lentis -Myopia -Glaucoma -Optic atrophy
- extensive atheroma formation at young age which affects many arteries but not the coronary arteries
Mortality/morbidity[edit | edit source]
The life expectancy of patients with homocystinuria is reduced only if untreated. It is known that before the age of 30, almost one fourth of patients die as a result of thrombotic complications (e.g. heart attack).
Treatment[edit | edit source]
No specific cure has been discovered for homocystinuria; however, many people are treated using high doses of vitamin B6 (also known as pyridoxine). Slightly less than 50% respond to this treatment and need to intake supplemental vitamin B6 for the rest of their lives. Those who do not respond require a low methionine diet, and most will need treatment with trimethylglycine. A normal dose of folic acid supplement and occasionally added cysteine in the diet is helpful.
Recommended diet[edit | edit source]
Low-protein food is recommended for this disorder requires food products which are low in particular types of amino-acid (i.e. methonine).
See also[edit | edit source]
[edit | edit source]
amino-acids Phenylketonuria - Alkaptonuria - Ochronosis - Tyrosinemia - Maple syrup urine disease - Propionic acidemia - Methylmalonic acidemia - Isovaleric acidemia - Primary carnitine deficiency - Cystinuria - Cystinosis - Hartnup disease - Homocystinuria - Citrullinemia - Hyperammonemia - Glutaric acidemia type 1
carbohydrates Lactose intolerance - Glycogen storage disease (type I, type II, type III, type IV, type V), Fructose intolerance, Galactosemia
Lipid storage disorders Gangliosidosis - GM2 gangliosidoses (Sandhoff disease, Tay-Sachs disease) - GM1 gangliosidoses - Mucolipidosis type IV - Gaucher's disease - Niemann-Pick disease - Farber disease - Fabry's disease - Metachromatic leukodystrophy - Krabbe disease - Neuronal ceroid lipofuscinosis - Batten disease - Cerebrotendineous xanthomatosis - Wolman disease - Cholesteryl ester storage disease
List of fatty acid metabolism disorders - Hyperlipidemia - Hypercholesterolemia - Familial hypercholesterolemia - Xanthoma - Combined hyperlipidemia - Lecithin cholesterol acyltransferase deficiency - Tangier disease - Abetalipoproteinemia
mineral metabolism Disorders of calcium metabolism - Hypophosphatemia - Hypophosphatasia - Wilson's disease - Menkes disease - Hypermagnesemia - Hypomagnesemia - Hypercalcaemia - Hypocalcaemia
fluid, electrolyte and acid-base balance Electrolyte disturbance - Hypernatremia - Hyponatremia - Respiratory acidosis - Metabolic acidosis - Lactic acidosis - Hypervolemia - Hypokalemia - Hyperkalemia - Mixed disorder of acid-base balance - Hyperchloremia - Hypochloremia - Dehydration
porphyrin and bilirubin Acatalasia - Gilbert's syndrome - Crigler-Najjar syndrome - Dubin-Johnson syndrome - Rotor syndrome - Porphyria (Acute intermittent porphyria, Gunther's disease, Porphyria cutanea tarda, Erythropoietic protoporphyria, Hepatoerythropoietic porphyria, Hereditary coproporphyria, Variegate porphyria)
glycosaminoglycan Mucopolysaccharidosis - Hurler syndrome - Hunter syndrome - Sanfilippo syndrome - Morquio syndrome
glycoprotein I-cell disease - Pseudo-Hurler polydystrophy - Aspartylglucosaminuria - Fucosidosis - Alpha-mannosidosis - Sialidosis
other Alpha 1-antitrypsin deficiency - Cystic fibrosis - Familial Mediterranean fever - Lesch-Nyhan syndrome
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