The aim of this research project is to compare the effect of an aerobic exercise session in two different populations. Sampling biological material and collecting health-related personal data entails minimal risks and burdens. Participants will be asked to perform 30 minutes of an aerobic exercise on an ergocycle at a fixed power output to correspond to a moderate intensity for a sedentary population.

Background Among genetic causes of hyperhomocysteinemia, classical homocystinuria, manifest not only with vascular diseases but also with neurological symptoms. This is related to the higher homocysteine concentration of up to 150-300 μmol/l without treatment. Recently, some articles have shown that mild and temporary hyperhomocysteinemia may follow exercise in a healthy population. Investigators hypothesized that increase in homocysteine may be of greater importance in patients with classical homocystinuria where cystathionine beta-synthase deficiency prevents homocysteine metabolism.

Objective To investigate the effect of an aerobic exercise in patients with classical homocystinuria on metabolic parameters compared to healthy controls.

Inclusion Criteria for subjects:

• Informed consent as documented by signature
• Confirmed biallelic mutation of cystathionine beta-synthase deficiency gene (homozygous or compound heterozygous) in an accredited Laboratory
• Continuation of their regular treatment under same dose (e.g. vitamin B6, B9 and B12, betaine) as prior to the study inclusion

Inclusion Criteria for controls:

- Healthy

Exclusion Criteria:

• Any clinically instable concomitant disease
• Individuals with acute cardiac events, syncope, rhythm disturbances or unstable hypertension in the past 6 months
• Individuals with vitamins B9 or B12 deficiencies
• Homocysteine > 100 µmol/l (for subjects)
• Homocysteine > 20 µmol/l (for controls)

Endocrinology Clinic