Homocystinuria, also known as Cystathionine beta synthase deficiency, is an inherited disorder of the metabolism of the amino acid methionine. It is an inherited autosomal recessive trait, which means the child is to inherit the defective gene from both parents. 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

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• A family history of homocystinuria
• Nearsightedness
• 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

Mortality/morbidity

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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

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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

Low-protein food is recommended for these disorder requires food products which are low in particular types of amino-acid (i.e. methonine).

See also

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• Cystinuria

External links

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• Homocystinuria Support

References

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• Medline Plus Medical Encyclopedia
• eMedicine

Genetic disorders