When a person has two copies of the MTHFR C677T gene mutation (homozygous) or one copy of MTHFR C677T and one copy of A1298C (compound heterozygous), decreased MTHFR enzyme activity slows down the homocysteine-to-methionine conversion process and can lead to a buildup of homocysteine in the blood.
Collision Coverage. When your insured vehicle overturns or collides with another object, Collision coverage pays for the damage to your vehicle. Collision coverage also may extend to a non-owned vehicle or one rented for personal use that is in your custody or that you are operating.
The other two numbers in the series above are explained here (auto insurance liability limits). Physical damage coverage, on the other hand, refers to damage to your own vehicle. Physical damage insurance is further broken down into collision insurance and comprehensive coverage. This type of coverage is not mandatory according to state law.