homocystinuria, CBS-related Carrier Screening (Genetic Testing) Overview

What is Homocystinuria, CBS-related?

Homocystinuria is an inherited metabolic condition that affects the body's ability to break down specific proteins. Homocystinuria, CBS-related, is caused by harmful genetic changes (variants) in the CBS gene. These changes result in missing or very low levels of an enzyme called cystathionine beta-synthase (CBS), which helps process an amino acid called homocysteine. When CBS is missing or not working correctly, homocysteine builds up in the blood and urine, which can lead to health problems in different parts of the body.

Infants with homocystinuria, CBS-related, may have trouble growing and gaining weight as expected. The condition can also affect the eyes, causing nearsightedness or a problem where the lens of the eye moves out of place (ectopia lentis). People with homocystinuria may have changes in their bones, such as a curved spine (scoliosis) or bones that break more easily (osteoporosis). Because of these changes, they may be taller and thinner than their family members. Individuals with homocystinuria, CBS-related, also have a risk of blood clots. These clots can form in the body and travel to important organs like the heart or brain, which can be life-threatening. Many individuals with the condition have learning difficulties, which can range from mild to more severe. Individuals with homocystinuria, CBS-related, can also experience seizures, mood changes, or behavior challenges.

Some people with homocystinuria respond to treatment with vitamin B6 (pyridoxine). These individuals typically experience milder symptoms than those who do not respond to treatment with vitamin B6.

How common is Homocystinuria, CBS-related?

The incidence of homocystinuria, CBS-related, is estimated to be 1 in 250,000 people worldwide. Studies have suggested that the condition may be more common in Ireland, Germany, Norway, and Qatar. While there are other types of homocystinuria, the most common type is homocystinuria, CBS-related.

How is Homocystinuria, CBS-related, treated?

The main goal of treatment is to keep homocysteine levels in the body as low as possible. This helps prevent serious health problems and allows people with homocystinuria to live healthier lives. Treatment should be started in the newborn period and is lifelong. People with homocystinuria usually follow a low-methionine diet. Methionine is an amino acid found in protein-rich foods like meat, fish, eggs, and dairy. Since methionine turns into homocysteine in the body, limiting it helps reduce harmful buildup. Many individuals need special medical formulas that provide essential nutrients without methionine. These formulas help support growth and development while keeping homocysteine levels safe. Vitamin B6 treatment is effective in 40-50% of individuals with homocystinuria, CBS-related. Those who are vitamin B6 responsive may need fewer dietary restrictions. A drug called betaine can also help reduce homocysteine levels. Other supplementation may include vitamin B12 (cobalamin) or vitamin B9 (folate).

To lower the risk of blood clots, individuals with homocystinuria, CBS-related, should avoid unnecessary surgery, oral contraceptives, dehydration, and prolonged periods of sitting or inactivity. Pregnant individuals with the condition should work with their doctor to manage clotting risks associated with pregnancy. Individuals should also avoid nitrous oxide, which is commonly used during dental procedures.

Individuals should consult specialists in ophthalmology, neurology, and orthopedics as needed to address other symptoms. Clinical trials for enzyme replacement therapy have yielded promising results and may become an option for treatment in the future.

What is the prognosis for an individual with Homocystinuria, CBS-related?

If diagnosed and treated early, most people with CBS-related homocystinuria can live a normal, healthy life. Without treatment, serious complications like blood clots can occur and may shorten life expectancy. Starting treatment in infancy is crucial.

Benefits of homocystinuria, CBS-related Carrier Screening (Genetic Testing)

Carrier screening is an important form of genetic testing for those who may be at risk of passing homocystinuria, cbs-related to their baby. Carrier Screening for homocystinuria, cbs-related can help in identifying that risk. The Foresight^® Carrier Screen helps clinicians guide care and empowers patients to take action to make the best decision for their families. Learn more about the Foresight^® Carrier Screen} by Myriad Genetics.