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Homocystinuria

Table of Contents

Homocystinuria

Homocysteinemia

Homocystinuria refers to a group of inherited disorders in which the body is unable to process amino acids properly. This leads to increased amounts of homocysteine and other amino acids in the blood and urine. Explore symptoms, causes, and genetics of this condition.

Homocystinuria

Image by National Eye Institute

About

Homocystinuria

Image by National Eye Institute

Homocystinuria

Homocystinuria

Image by National Eye Institute

What Is Homocystinuria?

Homocystinuria is an inherited disorder in which the body is unable to process certain building blocks of proteins (amino acids) properly.

The most common form of homocystinuria, called classic homocystinuria, is characterized by tall stature, nearsightedness (myopia), dislocation of the lens at the front of the eye, a higher risk of blood clotting disorders, and brittle bones that are prone to fracture (osteoporosis) or other skeletal abnormalities. Some affected individuals also have developmental delay and learning problems.

Less common forms of homocystinuria can cause intellectual disability, slower growth and weight gain (failure to thrive), seizures, and problems with movement. They can also cause and a blood disorder called megaloblastic anemia, which occurs when a person has a low number of red blood cells (anemia), and the remaining red blood cells are larger than normal (megaloblastic).

The signs and symptoms of homocystinuria typically develop during childhood, although some mildly affected people may not show signs and symptoms until adulthood.

Source: MedlinePlus Genetics

Additional Materials (7)

Homocystinuria - causes, symptoms, diagnosis, treatment, pathology

Video by Osmosis/YouTube

Homocystinuria Infographic

Video by HCU Network/YouTube

NORD - Classical Homocystinuria

Video by Osmosis/YouTube

Homocystinuria, Causes, Signs and Symptoms, Diagnosis and Treatment.

Video by Medical Centric/YouTube

Marfan Syndrome vs. Homocystinuria

Video by Medical Education for Visual Learners/YouTube

Methionine Cycle/Homocystinuria - CRASH! Medical Review Series

Video by Paul Bolin, M.D./YouTube

Homocystinuria Patient Testimonial - Anagnostopoulos

Video by HCU Network/YouTube

8:40

Homocystinuria - causes, symptoms, diagnosis, treatment, pathology

Osmosis/YouTube

3:57

Homocystinuria Infographic

HCU Network/YouTube

6:26

NORD - Classical Homocystinuria

Osmosis/YouTube

5:02

Homocystinuria, Causes, Signs and Symptoms, Diagnosis and Treatment.

Medical Centric/YouTube

1:07

Marfan Syndrome vs. Homocystinuria

Medical Education for Visual Learners/YouTube

16:15

Methionine Cycle/Homocystinuria - CRASH! Medical Review Series

Paul Bolin, M.D./YouTube

3:20

Homocystinuria Patient Testimonial - Anagnostopoulos

HCU Network/YouTube

Causes

Mutation

Image by National Human Genome Research Institute (NHGRI)

Mutation

A mutation is a change in a DNA sequence. Mutations can result from DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses.

Image by National Human Genome Research Institute (NHGRI)

What Causes Homocystinuria?

Homocystinuria can be caused by mutations in several different genes. All of these genes are responsible for making enzymes that are involved in the way our body uses and processes amino acids. The most common gene associated with homocystinuria is the CBS gene that causes a lack of the enzyme, cystathionine beta-synthase. Rarer causes of homocystinuria include mutations in the MTHFR,MTR, MTRR and MMADHC genes. It is not clear why high levels of homocysteine cause the symptoms seen in homocystinuria.

There are other, non-genetic causes of high levels of homocysteine. Non-genetic homocystinuria is not a rare condition. Some of the non-genetic causes are listed here.

Vitamin B6 or vitamin B12 deficiency
Folate deficiency
Low thyroid hormones (hypothyroidism)
Obesity
Diabetes
High cholesterol
Physical inactivity
High blood pressure
Certain medications (such as carbamazepine, atorvastatin, fenofibrate, methotrexate, phenytoin, and nicotinic acid)
Smoking
Advanced age

Source: Genetic and Rare Diseases (GARD) Information Center

Inheritance

autosomal recessive pattern of inheritance

Image by Thomas Shafee and TheVisualMD

autosomal recessive pattern of inheritance

Newborn autosomal recessive pattern of inheritance

Image by Thomas Shafee and TheVisualMD

How Is Homocystinuria Inherited?

The genetic forms of homocystinuria are inherited in an autosomal recessive pattern, which means both copies of the gene in every cell have mutations. This means that to have the condition, a person must have a mutation in both copies of the responsible gene in each cell. There is nothing either parent can do, before or during a pregnancy, to cause a child to have this.

People with homocystinuria inherit one mutation from each of their parents. The parents, who each have one mutation, are known as carriers. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:

25% chance to have the condition
50% chance to be an unaffected carrier like each parent
25% chance to be unaffected and not a carrier

Source: Genetic and Rare Diseases (GARD) Information Center

Symptoms

Myopia / Normal Eye

Normal Eye / Myopia

Interactive by National Eye Institute (NEI)

Myopia / Normal Eye

Normal Eye / Myopia

1) Normal Eye 2) Myopia - A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.

Interactive by National Eye Institute (NEI)

What Are the Signs and Symptoms of Homocystinuria?

Symptoms of the most severe form of homocystinuria will start in infancy or early childhood. he first of these symptoms may be poor growth and failure to gain weight. Other people with homocystinuria may not have any symptoms until adulthood. The most common symptom seen in adults with homocystinuria is an abnormal blood clot.

Other symptoms of untreated homocystinuria can include:

Eye:

Dislocation of the lens of the eye
Nearsightedness

Skeletal:

Caved-in chest (pectus excavatum)
Curvature of the spine (scoliosis)
Long, thin bones
Osteoporosis (weak, brittle bones)

Central nervous system:

Learning and intellectual disabilities
Psychiatric problems

Blood and heart:

Cardiovascular disease
Abnormal blood clots

Source: Genetic and Rare Diseases (GARD) Information Center

Additional Materials (3)

Myopia / Normal Vision

Myopia / Normal Vision

1) Myopia 2) Normal Vision

Interactive by Creative Commons

Homocystinuria

Homocystinuria

Image by National Eye Institute

Homocystinuria Infographic

Video by HCU Network/YouTube

Myopia / Normal Vision

Creative Commons

Homocystinuria

National Eye Institute

3:57

Homocystinuria Infographic

HCU Network/YouTube

Diagnosis

Newborn Screening of blood Samples

Image by TheVisualMD

Newborn Screening of blood Samples

Newborn Screening of blood Samples

Image by TheVisualMD

How Is Homocystinuria Diagnosed?

Most states in the US test for homocystinuria due to CBS deficiency at birth by newborn screening. A baby that has a positive newborn screening test needs to have additional blood testing to look for high levels of homocysteine and methionine in the blood. Genetic testing can also be helpful for diagnosis.

A child or an adult with dislocation of the lens of the eye may also get tested for homocystinuria using blood and urine testing. In addition, a child or adult who has a blood clot, especially at an early age, may also get tested for homocystinuria.

Source: Genetic and Rare Diseases (GARD) Information Center

Homocysteine Test

Homocysteine Test

Also called: Homocyst(e)ine, Homocysteine Cardiac Risk

A homocysteine test measures the level of homocysteine in your blood. High levels may mean a vitamin deficiency, heart disease, or an inherited disorder.

Homocysteine Test

Also called: Homocyst(e)ine, Homocysteine Cardiac Risk

A homocysteine test measures the level of homocysteine in your blood. High levels may mean a vitamin deficiency, heart disease, or an inherited disorder.

{"label":"Homocysteine Reference Range","scale":"lin","step":0.1,"hideunits":false,"units":[{"printSymbol":"mg\/L","code":"mg\/L","name":"milligram per liter"}],"items":[{"flag":"abnormal","label":{"short":"Low","long":"Low","orientation":"horizontal"},"values":{"min":0,"max":0.68},"text":"Immune system function is impaired when levels of homocysteine are too low. Individuals with low homocysteine have limited capacity for response to oxidative stress and certain kinds of toxin exposure.","conditions":["Genetic disorders","Kidney disease","Leukemia","Psoriasis"]},{"flag":"normal","label":{"short":"Normal","long":"Normal","orientation":"horizontal"},"values":{"min":0.68,"max":2.02},"text":"Homocysteine is an amino acid found in most cells of the body, in trace amounts. Normally, homocysteine levels are low, because it is constantly turned into other substances your body needs.","conditions":[]},{"flag":"abnormal","label":{"short":"High","long":"High","orientation":"horizontal"},"values":{"min":2.02,"max":5},"text":"Elevated homocysteine levels are associated with heart attack, stroke, and blood clots. They're also associated with renal disease as well as with low levels of several B vitamins. In pregnant women, elevated homocysteine levels may affect fetal development, especially of the nervous system.","conditions":["Vitamin B deficiency","Chronic kidney failure","Homocystinuria","Coronary artery disease"]}],"value":1.4}[{"abnormal":0},{"normal":0},{"abnormal":0}]
Use the slider below to see how your results affect your health.
mg/L
0.68
2.02
Your result is Normal.
Homocysteine is an amino acid found in most cells of the body, in trace amounts. Normally, homocysteine levels are low, because it is constantly turned into other substances your body needs.
Related conditions
A homocysteine test may be used to:
- Find out if you're lacking vitamin B6, B12, or folic acid. These vitamins break down homocysteine. So if you don't have enough of them, your homocysteine levels will increase. A homocysteine test may be done with a blood test to measure your vitamin B levels.
- Help diagnose homocystinuria. Homocystinuria is a rare, genetic disease that prevents your body from using a certain amino acid to make important proteins. Symptoms usually show up in the first year of life, but they may not appear until childhood or later. Common symptoms include problems with eyesight, blood clots, and weak bones. In the U.S., most newborns have a routine screening test to check for homocystinuria.
- Better understand your risk for heart attack or stroke if you already have an increased risk. Your health care provider may order a homocysteine test if you have been diagnosed with heart or blood vessel disease or if you have conditions that increase your risk for heart and blood vessel disease, such as:
  High blood pressure
  High cholesterol
  Diabetes
Medical experts don't recommend routine homocysteine testing to screen for heart disease risk in everyone. That's because researchers aren't sure how much homocysteine levels affect heart and blood vessel diseases. And so far, studies have shown that lowering homocysteine levels doesn't reduce the risk of heart attack or stroke.
You may need this test if you have symptoms that suggest you lack vitamin B12 or folic acid. The symptoms may be very mild to severe and may include:
- Dizziness
- Fatigue and/or weakness
- Headache
- Heart palpitations (racing or pounding heart)
- Changes in the color of your skin or fingernails
- Sores on your tongue or in your mouth
- Tingling or numbness in your hands, feet, arms, and/or legs
Your provider may order this test if you have a high risk for low levels of vitamin B12 or folic acid because you:
- Have malnutrition.
- Are an older adult. Older people often can't absorb enough vitamin B12 from food.
- Have alcohol use disorder or a drug addiction.
Your provider may recommend this test if you:
- Have had a heart attack or stroke
- Have one or more conditions that increase your risk for heart attack or stroke, such as high LDL "bad" cholesterol or high blood pressure
A high homocysteine level may be a sign that:
- You are not getting enough vitamin B12 or folic acid in your diet.
- You (or your child) have homocystinuria. You will probably need more testing to rule out or confirm a diagnosis of homocystinuria.
- You may have a higher risk of heart disease, stroke, or other blood vessel disorders.
Higher than normal homocysteine levels may also happen with other conditions, such as osteoporosis, chronic kidney disease, hypothyroidism, or Alzheimer's disease or other types of dementia.
If your homocysteine levels are high, it doesn't always mean you have a medical condition that needs treatment. Your results may be affected by:
- Your age. Homocysteine levels may get higher as you get older.
- Your sex. Males usually have higher homocysteine levels than females, but levels in females increase after menopause.
- Smoking
If you have questions about your results, talk with your provider.
1. Homocysteine Test: MedlinePlus Lab Test Information [accessed on Sep 30, 2018]
2. Homocysteine [accessed on Sep 30, 2018]
3. 706994: Homocyst(e)ine | LabCorp [accessed on Sep 30, 2018]
4. Homocysteine Blood Test [accessed on Sep 30, 2018]
5. Fontanarosa, P., & Christiansen, S. (2009, April 01). Laboratory Values. AMA Manual of Style. Ed. [accessed on Sep 30, 2018]
6. https://www.drkarafitzgerald.com/2017/04/04/low-homocysteine-concern/ [accessed on Sep 30, 2018]

Normal reference ranges can vary depending on the laboratory and the method used for testing. You must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

Additional Materials (8)

CRP And Homocysteine Inflammation Markers, How Do They Relate To Coronary Artery Disease? - Dr. Lyel

Video by EmpowHER/YouTube

This browser does not support the video element.

What Is Inflammation?

Inflammation is the body's response to damage. It takes many forms. Chronic inflammation is common in overweight and obese people, because their fat cells manufacture damaging substances that trigger a reaction from the immune system's white blood cells. Keeping track of a key biomarker for inflammation, C-reactive Protein or CRP, helps doctors determine whether an overweight patient is at risk for such conditions as heart disease, dementia, diabetes, cancers, and more.

Video by TheVisualMD

Homocystinuria Infographic

Video by HCU Network/YouTube

The Homocysteine Factor

Video by hcyfactor/YouTube

Homocysteine

homocysteine molecule (L-isomer).

Image by Ben Mills and Jynto

Homocysteine

Homocysteine is a non-proteinogenic amino acid. It is a homologue of the amino acid cysteine, differing by an additional methylene (-CH2-) group. It is biosynthesized from methionine, and can be recycled into methionine or converted into cysteine with the aid of B-vitamins. While detection of high levels of homocysteine has been linked to cardiovascular disease, lowering homocysteine levels may not improve outcomes.

Image by TheVisualMD

Fasting for a Blood Test | WebMD

Video by WebMD/YouTube

Fasting Plasma Glucose

Fasting Plasma Glucose - The fasting plasma glucose (FPG) test, also known as the fasting blood sugar test, measures blood sugar levels and is used to diagnose diabetes.

Image by TheVisualMD

2:12

CRP And Homocysteine Inflammation Markers, How Do They Relate To Coronary Artery Disease? - Dr. Lyel

EmpowHER/YouTube

1:57

What Is Inflammation?

TheVisualMD

3:57

Homocystinuria Infographic

HCU Network/YouTube

3:23

The Homocysteine Factor

hcyfactor/YouTube

Homocysteine

Ben Mills and Jynto

Homocysteine

TheVisualMD

0:50

Fasting for a Blood Test | WebMD

WebMD/YouTube

Fasting Plasma Glucose

TheVisualMD

Newborn Screening Tests

Newborn Blood Spot Screening

Also called: Newborn Blood Spot Test, NBS, Neonatal Heel Prick Test

Right after birth, babies need many important tests and procedures to ensure their health. Newborn screening detects disabling or possibly fatal conditions early enough so that treatments can reduce disability or death from that condition. The screening generally includes a variety of blood tests and a hearing test.

Newborn Blood Spot Screening

Also called: Newborn Blood Spot Test, NBS, Neonatal Heel Prick Test

Right after birth, babies need many important tests and procedures to ensure their health. Newborn screening detects disabling or possibly fatal conditions early enough so that treatments can reduce disability or death from that condition. The screening generally includes a variety of blood tests and a hearing test.

{"label":"Blood spot screening reference range","scale":"lin","step":0.5,"hideunits":true,"items":[{"flag":"normal","label":{"short":"In-range (normal)","long":"In-range (normal)","orientation":"horizontal"},"values":{"min":0,"max":1},"text":"An in-range (also called negative, normal, or low risk) result means that your baby probably does not have a condition detected by blood spot screening. Babies with in-range results do not need more testing.","conditions":[]},{"flag":"borderline","label":{"short":"Borderline","long":"Borderline","orientation":"horizontal"},"values":{"min":1,"max":2},"text":"A borderline (also called inconclusive or medium risk) result means that your baby\u2019s screening results fall somewhere between an in-range and out-of-range result. Babies with borderline results need more screening or testing.","conditions":[]},{"flag":"abnormal","label":{"short":"Out-of-range (abnormal)","long":"Out-of-range (abnormal)","orientation":"horizontal"},"values":{"min":2,"max":3},"text":"An out-of-range (also called positive, abnormal, or high risk) result means that your baby might have the condition detected by the screening test. Babies with out-of-range results need more testing.","conditions":["Disorders Detected by Newborn Screening"]}],"value":0.5,"disclaimer":"Normal reference ranges can vary depending on the laboratory and the method used for testing. You must use the range supplied by the laboratory that performed your test to evaluate whether your results are \"within normal limits.\""}[{"normal":0},{"borderline":0},{"abnormal":0}]
Use the slider below to see how your results affect your health.
Your result is In-range (normal).
An in-range (also called negative, normal, or low risk) result means that your baby probably does not have a condition detected by blood spot screening. Babies with in-range results do not need more testing.
Related conditions
1. Newborn Screening. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) [accessed on Jan 09, 2019]
2. What is newborn screening? - Genetics Home Reference - NIH [accessed on Jan 09, 2019]
3. Newborn screening tests: MedlinePlus Medical Encyclopedia [accessed on Jan 09, 2019]
4. Newborn blood spot test - NHS [accessed on Jan 09, 2019]
5. Frequently Asked Questions About Newborn Bloodspot Screening | National Newborn Screening and Global Resource Center [accessed on Jan 09, 2019]
6. New York | Baby's First Test | Newborn Screening | Baby Health [accessed on Jan 09, 2019]
7. Newborn Screening | Lab Tests Online [accessed on Jan 09, 2019]
8. Newborn Screening Tests (for Parents) [accessed on Jan 09, 2019]

Additional Materials (24)

Newborn screening

Newborn baby feet and letters of A, T, C G.

Image by www.genome.gov

Newborn Screening

Newborn screening tests use a dried blood sample collected during the first week after birth to measure the presence of disease biomarkers (a measurable substance or characteristic that is indicative of a disease).

Image by National Human Genome Research Institute (NHGRI)

Infographic Newborn screening system

Infographic Newborn screening system

Image by Colorado Department of Public Health and Environment

The Public Health Lab: Newborn Screening

Video by mnhealth/YouTube

Cystic Fibrosis Newborn Screening.

Video by Nemours/YouTube

Newborn Screening and Fabry Disease: What We Know and Don't Know

Video by Rare Disease Report/YouTube

Newborn Hearing Screening - Boys Town National Research Hospital

Video by BoysTownHospital/YouTube

Beyond the Blood Spot: Newborn Screening for Hearing Loss and Critical Congenital Heart Disease

Video by Centers for Disease Control and Prevention (CDC)/YouTube

What is newborn screening? Animated video for parents.

Video by PerkinElmer, Inc./YouTube

Newborn Screening

Video by Mayo Clinic/YouTube

Cystic Fibrosis Newborn Screening Information for Pediatricians

Video by Nemours/YouTube

Newborn screening test: guidelines for care providers

Video by Sunnybrook Hospital/YouTube

Newborn Screening: A Personal Story

Video by March of Dimes/YouTube

Your Newborn's Health Screening

Video by KK Women's and Children's Hospital/YouTube

Cystic Fibrosis Newborn Screening | Cincinnati Children's

Video by Cincinnati Children's/YouTube

How Newborn Hearing Screening Helps Children

Video by Washington State Department of Health/YouTube

X-Linked Adrenoleukodystrophy: Newborn Screening in Males

Video by The WSRGN/YouTube

HGP10 Symposium: Whole Genome Sequencing in Newborn Screening - Jeff Botkin

Video by National Human Genome Research Institute/YouTube

Expanding Newborn Screening to X-ALD — What Else Might We Find and How Will This Impact Patients?

Video by UW Video/YouTube

Beyond the Blood Spot: Newborn Screening for Hearing Loss and Critical Congenital Heart Disease

Video by Centers for Disease Control and Prevention (CDC)/YouTube

California Department of Public Health's Newborn Screening Program

Video by CA Public Health/YouTube

SCID

Video by Immune Deficiency Foundation/YouTube

Phenylketonuria (PKU)

Video by Nutricia Metabolics/YouTube

WHAT IS MLD? Metachromatic Leukodystrophy explained to all

Video by YourekaScience/YouTube

Newborn screening

www.genome.gov

Newborn Screening

National Human Genome Research Institute (NHGRI)

Infographic Newborn screening system

Colorado Department of Public Health and Environment

1:52

The Public Health Lab: Newborn Screening

mnhealth/YouTube

5:50

Cystic Fibrosis Newborn Screening.

Nemours/YouTube

3:37

Newborn Screening and Fabry Disease: What We Know and Don't Know

Rare Disease Report/YouTube

1:54

Newborn Hearing Screening - Boys Town National Research Hospital

BoysTownHospital/YouTube

14:52

Beyond the Blood Spot: Newborn Screening for Hearing Loss and Critical Congenital Heart Disease

Centers for Disease Control and Prevention (CDC)/YouTube

3:19

What is newborn screening? Animated video for parents.

PerkinElmer, Inc./YouTube

2:25

Newborn Screening

Mayo Clinic/YouTube

8:16

Cystic Fibrosis Newborn Screening Information for Pediatricians

Nemours/YouTube

2:45

Newborn screening test: guidelines for care providers

Sunnybrook Hospital/YouTube

3:25

Newborn Screening: A Personal Story

March of Dimes/YouTube

9:30

Your Newborn's Health Screening

KK Women's and Children's Hospital/YouTube

2:42

Cystic Fibrosis Newborn Screening | Cincinnati Children's

Cincinnati Children's/YouTube

3:02

How Newborn Hearing Screening Helps Children

Washington State Department of Health/YouTube

6:20

X-Linked Adrenoleukodystrophy: Newborn Screening in Males

The WSRGN/YouTube

35:56

HGP10 Symposium: Whole Genome Sequencing in Newborn Screening - Jeff Botkin

National Human Genome Research Institute/YouTube

1:00:03

Expanding Newborn Screening to X-ALD — What Else Might We Find and How Will This Impact Patients?

UW Video/YouTube

1:04:18

Beyond the Blood Spot: Newborn Screening for Hearing Loss and Critical Congenital Heart Disease

Centers for Disease Control and Prevention (CDC)/YouTube

3:24

California Department of Public Health's Newborn Screening Program

CA Public Health/YouTube

7:55

SCID

Immune Deficiency Foundation/YouTube

7:07

Phenylketonuria (PKU)

Nutricia Metabolics/YouTube

5:57

WHAT IS MLD? Metachromatic Leukodystrophy explained to all

YourekaScience/YouTube

Prognosis

Blood clots

Image by Fuzis

Blood clots

Red blood cells trapped in a fibrin network in a blood clot.

Image by Fuzis

What Is the Long-Term Outlook for People with Homocystinuria?

Lowering the level of homocysteine in the blood, either with diet or supplements or both, can prevent symptoms. With treatment, people with the most severe form of homocystinuria can have normal growth and development. Some may still have eye problems or blood clots and should be monitored. Blood clots can be serious and cause organ damage.

Treatment for milder forms of homocystinuria may depend on clinical symptoms and the level of homocysteine in the blood.

Source: Genetic and Rare Diseases (GARD) Information Center

Statistics

Illustration of rare disease incidence

Image by mcmurryjulie/Pixabay

Illustration of rare disease incidence

Image by mcmurryjulie/Pixabay

How Common Is Homocystinuria?

Classic homocystinuria affects at least 1 in 200,000 to 335,000 people worldwide. The disorder appears to be more common in some countries, such as Ireland (1 in 65,000), Germany (1 in 17,800), Norway (1 in 6,400), and Qatar (1 in 1,800). The rarer forms of homocystinuria each have a small number of cases reported in the scientific literature.

Source: MedlinePlus Genetics

Related HealthJournals

Homocystinuria due to CBS Deficiency

Homocystinuria due to CBS deficiency is a genetic condition that results from poor metabolism of folate (also called vitamin B9), due to a lack of working enzyme called cystathionine beta-synthase (CBS). Explore symptoms, causes, and genetics of this condition.

Homocystinuria due to MTHFR Deficiency

Homocystinuria due to MTHFR deficiency is a genetic condition that results from poor metabolism of folate (also called vitamin B9), due to a lack of working enzyme called methylenetetrahydro-folate reductase (MTHFR).

Genetic Testing

Genetic testing is a type of medical test that identifies changes in chromosomes, genes, or proteins. Over 2000 tests are available. Genetic testing may be done for many reasons, from newborn baby screening to diagnosing certain diseases. Read about why you might consider testing.

Amino Acid Metabolism Disorders

Disorders like phenylketonuria (PKU) and maple syrup urine disease cause problems with how your body uses proteins. Learn more about them.

Isobutyryl-CoA Dehydrogenase Deficiency

Isobutyryl-CoA dehydrogenase (IBD) deficiency is an inborn error of valine (an amino acid) metabolism. This can lead to a harmful amount of organic acids and other toxins in the body. Learn about causes, symptoms, and treatment of this rare condition.

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Homocystinuria

Homocystinuria refers to a group of inherited disorders in which the body is unable to process amino acids properly. This leads to increased amounts of homocysteine and other amino acids in the blood and urine. Explore symptoms, causes, and genetics of this condition.

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