They are at least a thousand times larger than the 1980 eruption of Mount St. Helens, which produced only 1 km3 (0.2 cu mi) of material, and at least six times larger than the 1815 eruption of Mount Tambora, the largest eruption in recent history, which produced 160 km3 (38 cu mi) of volcanic deposits.
Listen. 1  This severe homocystinuria is caused by rare MTHFR gene mutations (sometimes in combination with a second common MTHFR gene mutation). In severe MTHFR deficiency, signs and symptoms become apparent in infancy, however the condition can be milder, presenting in later childhood or adulthood.
Homocysteine: An amino acid that is normally present in blood. Homocystinuria: A severe form of hyperhomocysteinemia. Hypercoagulable state: A condition in which a person has an increased tendency to form blood clots. Also called thrombophilia. Hyperhomocysteinemia: A form of acquired thrombophilia resulting from a high level of homocysteine in the blood. Hypothyroidism: A medical condition caused by deficient thyroid activity.