Homocystinuria due to CBS deficiency is an inherited disorder in which the body is unable to process certain building blocks of proteins (amino acids) properly. This form of homocystinuria is caused by the lack of an enzyme called cystathionine beta-synthase, which results from a mutation in the CBS gene. It is characterized by dislocation of the lens in the eye, an increased risk of abnormal blood clots, and skeletal abnormalities. Problems with development and learning are also evident in some cases. Homocystinuria due to CBS deficiency is inherited in an autosomal recessive pattern. Treatment aims to correct the biochemical abnormalities, especially to control blood homocystine concentration and prevent thrombosis (blood clots). Vitamin B6 (pyridoxine) therapy, protein-restricted and methionine-restricted diets, betaine treatment, and/or folate and vitamin B12 supplementation may be used to manage the condition.
The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
|Signs and Symptoms||Approximate number of patients (when available)|
|Abnormality of the teeth||90%|
|Disproportionate tall stature||90%|
|Reduced bone mineral density||90%|
|Abnormal hair quantity||50%|
|Limitation of joint mobility||50%|
|Abnormality of retinal pigmentation||7.5%|
|Abnormality of the palate||7.5%|
|Elevated hepatic transaminases||7.5%|
|Failure to thrive||7.5%|
|Autosomal recessive inheritance||-|
|Biconcave vertebral bodies||-|
|Hypopigmentation of the skin||-|
|Mitral valve prolapse||-|
Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.
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Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD. Suggest an organization to add.
Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.