590 likes | 2.52k Views
By Aisha Zaheer. HOMOCYSTINURIA. What is it?. Inherited autosomal recessive disorder of methionine metabolism. This results in an accumulation of homocysteine and its metabolites in plasma and urine. P athophysiology.
E N D
By Aisha Zaheer HOMOCYSTINURIA
What is it? • Inherited autosomal recessive disorder of methionine metabolism. • This results in an accumulation of homocysteine and its metabolites in plasma and urine.
Pathophysiology • This condition occurs when an enzyme called “cystathionine beta-synthase” (CBS) is either missing or not working properly. • This enzymeis responsible for breaking down methionine. • When the CBS enzyme is not working correctly, methionine and another amino acid, homocysteine,buildup in the blood and cause problems.
This occurs due to mutation in CBS gene,present on chromosome 21 which codes for CBS enzyme
Signs & Symptoms • Muscle weakness • Bone thinning • Heart stroke • Long and thin limbs • Spidery fingers • Intellectual disability • Retarded mental and physical growth • Nearsightedness or lens dislocation
Diagnosis • Family history • Physical examination • Amino acid screen of blood and urine • Diagnosis depends on measurement of CBS activity. • Genetic testing • Skeletal X-ray to detect any bone defect like osteoporosis • Standard ophthalmic test
Treatment • Low-methionine diet • Supplements like: Pyridoxine (B6) supplements because it acts as a coenzyme for CBS enzyme. Betaine Vitamin B12 Folic acid cysteine
References • http://ghr.nlm.nih.gov/condition/homocystinuria • http://www.nlm.nih.gov/medlineplus/ency/article/001199.htm • http://emedicine.medscape.com/article/1952251-overview#a11 • http://www.newbornscreening.info/Parents/aminoaciddisorders/CBS.html • http://www.perkinelmergenetics.com/Homocystinuria.htm • www.ncbi.nlm.nih.gov