Incidence of the Anomaly including Specific groups at risk
Homocystinuria is a rare health condition that impedes the body’s ability to metabolize the amino acid methionine. It is a genetically inherited condition where a child receives an abnormal gene from a parent. The incidence of homocystinuria is directly linked to the cumulative detection rate of cystathionine beta-synthase (CBS) deficiency. From the available data, the incidence rate of homocystinuria is one child in every 200,000 to 335,000 people globally (“ Homocystinuria," 2019 ).
Clinical Manifestations
Deficient enzyme cystathionine beta-synthase is the leading cause of homocystinuria. The nervous system, blood, and lymph are the most affected in the body. Clinical manifestations of homocystinuria include brain damage, seizures, and resultant death ( Kenner & Lewis, 2013 ). The manifestations can range from mild to severe.
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Pathophysiology
Regarding the pathophysiology of homocystinuria, the body produces insufficient enzyme cystathionine beta-synthase, which leads to the accumulation of homocysteine in the blood plasma, urine, and body tissues. In normal circumstances, methionine is converted to homocysteine, which is either permanently degraded to cysteine by enzyme CBS or converted back to methionine by methionine synthase (“ National Organization for Rare Disorders," 2018 ).
Inheritance Factor
Fundamentally, homocystinuria is associated with mutation of the gene that regulates enzyme CBS. The mutated gene is then inherited in an autosomal receding pattern. A child has a 25% probability of having the condition if both of his parents are carriers with each pregnancy while a child of carrier parents has a 50% chance also to become a carrier of the mutated gene (“ National Organization for Rare Disorders," 2018 ).
Benefits of Screening and Why Screening Indicated
Screening for homocystinuria is the primary source of diagnostic information. Screening tests are conducted to ascertain the amount of homocysteine in urine and the level of amino acids in the blood. Other tests include genetic tests, enzyme tests, and liver biopsies.
Management of the Disorder (How to treat the disorder)
Management of homocystinuria is through pyridoxine, vitamin B12 and folic acid supplements, and cysteine supplements ( Valayannopoulos et al., 2019 ). The principal objective of managing homocystinuria in infants is to ensure the development of normal intelligence and prevent further escalation of other complications.
In conclusion, homocystinuria is a disorder that is associated with the mutation of the gene that regulates enzyme CBS. Insufficiency of CBS results in the accumulation of homocysteine, affecting the healthy growth of an infant. The condition can be managed through the use of pyridoxine, vitamin B12 and folic acid supplements, and cysteine supplements.
References
Homocystinuria. (2019). Genetics Home Reference. Retrieved 5 October 2019, from ghr.nlm.nih.gov/condition/homocystinuria#definition
Kenner, C., & Lewis, J. (2013). Genetics and Genomics for Nursing (1st ed.). New York City: Pearson.
National Organization for Rare Disorders (NORD). (2018). Homocystinuria due to Cystathionine Beta-Synthase Deficiency . Danbury: National Organization for Rare Disorders (NORD). Retrieved from rarediseases.org/rare-diseases/homocystinuria-due-to-cystathionine-beta-synthase-deficiency/
Valayannopoulos, V., Schiff, M., Guffon, N., Nadjar, Y., García-Cazorla, A., Casanova, M. M. P., ... & Rigalleau, V. (2019). Betaine Anhydrous In Homocystinuria: Results From The Roch Registry. Orphanet Journal of Rare Diseases , 14 (1), 66.
