Classification and external resources

ICD-10 E72.1
ICD-9 270.4
OMIM 236200
DiseasesDB 5991
MedlinePlus 001199
eMedicine derm/708
MeSH D006712

Homocystinuria, also known as cystathionine beta synthase deficiency or CBS deficiency,[1] 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.



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.

Possible Signs and symptoms


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).


No specific cure has been discovered for homocystinuria; however, many people are treated using high doses of vitamin B6 (also known as pyridoxine).[4] 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 adding cysteine to the diet can be helpful.

Betaine (N,N,N-trimethylglycine) is used to reduce concentrations of homocysteine by promoting the conversion of homocysteine back to methionine. The re-formed methionine is then gradually removed by incorporation into body protein. The methionine that is not converted into protein is converted to S-adenosyl-methionine which goes on to form homocysteine again. Betaine is, therefore, only effective if the quantity of methionine to be removed is small. Hence treatment consists of a diet low in methionine and betaine. In classical homocystinuria (CBS) the plasma methionine usually increases above the normal range of 30 micromoles/L and the concentrations should be monitored as potentially toxic levels (more than 400 micromole/l) may be reached.

Recommended diet

Low-protein food is recommended for this disorder, which requires food products low in particular types of amino-acid (e.g. methionine).

See also

External links


  1. ^ a b Online 'Mendelian Inheritance in Man' (OMIM) 236200
  2. ^ Maillot F, Kraus JP, Lee PJ (2008). "Environmental influences on familial discordance of phenotype in people with homocystinuria: a case report". J Med Case Reports 2 (1): 113. doi:10.1186/1752-1947-2-113. PMC 2377250. PMID 18423051. http://www.jmedicalcasereports.com/content/2//113. 
  3. ^ Peter Nicholas Robinson; Maurice Godfrey (2004). Marfan syndrome: a primer for clinicians and scientists. Springer. pp. 5–. ISBN 9780306482380. http://books.google.com/?id=eX4B9WASDpAC&pg=PA5. Retrieved 12 April 2010. 
  4. ^ Bakker, R. C.; Brandjes, D. P. (Jun 1997). "Hyperhomocysteinaemia and associated disease". Pharmacy world & science : PWS 19 (3): 126–132. doi:10.1023/A:1008634632501. PMID 9259028.  edit

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Look at other dictionaries:

  • homocystinuria — homocystinuria. См. гомоцистинурия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • homocystinuria — ▪ pathology       hereditary metabolic disorder involving methionine, a sulfur containing essential amino acid. The metabolic sequence of methionine normally begins with its stepwise conversion to homocysteine, cystathionine, and cysteine,… …   Universalium

  • Homocystinuria — A genetic disease due to an enzyme deficiency. Among other events, there is a buildup of the amino acid homocystine. Progressive mental retardation is common in untreated cases. The finding of vascular disease and premature arteriosclerosis in… …   Medical dictionary

  • homocystinuria — Recessive condition in which the enzyme (cystathione synthetase) that converts homocysteine and serine into cystathione, a precursor of cysteine, is missing. Deficiency of this enzyme has widespread consequences in connective tissue, circulation… …   Dictionary of molecular biology

  • homocystinuria — noun An inherited metabolic disorder characterised by the presence of homocysteine in the urine …   Wiktionary

  • homocystinuria — ho·mo·cys·ti·nu·ria …   English syllables

  • homocystinuria — n. an inborn error of metabolism, inherited as an autosomal recessive trait, caused by an enzyme deficiency resulting in an excess of homocysteine in the blood and the presence of homocystine in the urine. Clinically affected individuals are… …   The new mediacal dictionary

  • homocystinuria — ˌhōməˌsistə̇ˈn(y)u̇rēə, ˌhäm noun Etymology: New Latin, from English homocystine + New Latin uria : a metabolic disorder inherited as a recessive autosomal trait, caused by deficiency of an enzyme important in the metabolism of homocystine with… …   Useful english dictionary

  • гомоцистинурия — (homocystinuria; гомоцистин + греч. uron моча) наследственная болезнь, обусловленная нарушением обмена метионина вследствие недостаточности L сериндегидрогеназы с накоплением в тканях гомоцистина; клинически проявляется нарушениями формирования… …   Большой медицинский словарь

  • Гомоцистинури́я — (homocystinuria; гомоцистин + греч. uron моча) наследственная болезнь, обусловленная нарушением обмена метионина вследствие недостаточности L сериндегидрогеназы с накоплением в тканях гомоцистина; клинически проявляется нарушениями формирования… …   Медицинская энциклопедия

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