CBS gene mutation

Get tested for CBS gene mutation here.

What are CBS gene mutations?

CBS (cystathionine beta synthase) catalyzes the first step of the transsulfuration pathway, from homocysteine to cystathionine. CBS defects are actually an upregulation of the CBS enzyme. This means the enzyme works too fast.  In these patients, it’s common to see low levels of cystathionine and homocysteine since there is a rapid conversion to taurine. This leads to high levels of taurine and ammonia. The CBS upregulation has been clinically observed to result in sulfur intolerance in some patients. It has also been observed that BH4 can also become depleted with a CBS upregulation.

BH4 helps regulate neurotransmitters and mood. Other mutations, such as MTHFR A1298C, chronic bacterial infections, and aluminum can also lead to low BH4 levels. Lack of BH4 can lead to mast cell degranulation and possibly mast cell activation disorder (MCAD).

CBS problems / Symptoms

Possible high (excess) copper:

  • Nervous system – anxiety, agitation, depression, aggression
  • Neurological disorders – impaired mental function, dyslexia, learning disabilities, emotional disturbances
  • Blood – iron deficiency anemia
  • Liver impairment – Wilson’s disease
  • Immune system – prolonged viral infections, fungal infections, poor wound healing
  • Thyroid Gland – Thyroid insufficiency and hypothyroidism
  • Reproductive Hormonal imbalances – Premenstrual Syndrome (PMS)
  • Adrenal Gland – Adrenal insufficiency and weakness
  • Gastrointestinal – constipation, gastritis
  • Cardiovascular – hypercholesterolemia
  • Gallbladder – abnormal function, gallstone formation
  • Musculoskeletal – scoliosis, poor collagen and elastin production, osteoarthritis


  • Possible low zinc (Poor sense of taste or smell, white marks on more than two fingernails, frquent infections, stretch marks, acne or greasy skin, low fertility, pale skin, tendency to depression, loss of appetite)
  • Possible pyrroles
  •  Low homocysteine
  • Sleep problems – low serine getting to sleep
  • Oxidative stress – low cysteine therefore low glutathione
  • Gut problems that may increase ammonia
  • Increased hydrogen sulfide will usually present as dizziness/low blood pressure
  • High homocysteine – Low H2S will usually mean high blood pressure, low cysteine/low B6
  • Inability to tolerate onion, garlic, eggs, cabbage (ie: high sulphur foods, Preservative 220 (sulphur dioxide) in wine & foods
  • BH4 deficiency (Depression, anxiety, mood problems, panic attacks)
  • Molybdenum deficiencies (Excess copper or sulphate interferes with its utilization, breathing difficulty, neurological disorders
  • Vitamin B1, deficiencies (Tender muscles, eye pains, panic attacks, irritability, poor concentration, prickly legs, poor memory, stomach pains, constipation, tingling hands, and rapid heartbeat)
  •  B2 deficiencies (Burning or gritty eyes, sensitivity to bright lights, sore tongue, cataracts, dull or oily hair, eczema, dermatitis, split nails, cracked lips)
  • Vitamin B6 deficiencies (Infrequent dream recall, water retention, tingling hands, depression, nervousness, irritability, muscle tremors or cramps, lack of energy, flaky skin)

Note: While some physicians think the CBS mutation is one of the most important mutations to address, there is very little medical research to support these claims and some doctors in the field disagree. In normal populations, studies have shown CBS upregulations to be protective against high homocysteine. However, CBS upregulations have shown to be harmful in Down Syndrome. Medical research has not determined if CBS upregulations are harmful in those with syndromes or disorders leading to impaired methylation.

CBS Methylation & Methionine / Homocysteine Pathways

  • CBS A13637G
  • A360A
  • CBS C*351T
  • CBS C1915OT
  • Test C699T
  • CBS G*299A
  • Test CBS T*330C

CBS Trans-Sulfuration Pathway

  • CBS A13637G
  •  A360A
  • CBS C*351T
  • CBS C19150T
  • (Test) CBS C699T
  • CBS G*299A
  • CBS T*330C

Looking for CBS gene mutation treatments, contact us here.